A water-based metallic flash base paint, a preparation method and application thereof

Abstract

The present application relates to the technical field of vehicle coating, and discloses a water-based metal flash base paint, a preparation method and application thereof. The water-based metal flash base paint is composed of component A and component B with a mass ratio of 100:(0-10). A high glass transition temperature water-based polycarbonate aliphatic anion polyurethane dispersion and a low glass transition temperature water-based aliphatic anion polyurethane dispersion are selected and compounded as a film-forming resin, and a water-based self-crosslinking low-hydroxyl acrylate dispersion is selectively added. Through the synergistic effect and specific ratio of the raw material components, the characteristics of different types of water-based resins are brought to the best state, so that the water-based metal flash base paint has good gloss, thixotropy, good directional arrangement of aluminum powder, no blooming, good gun matching, improved thixotropy, good flicker intensity, excellent mechanical properties and corrosion resistance, and high practical value and popularization value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle coatings, in particular to a water-based metallic flash base paint, a preparation method and application thereof. BACKGROUND

[0002] Rail transit vehicles are a major means of public transportation, and most rail transit vehicles are manufactured using lightweight aluminum alloys instead of steel. With the change in the material of the vehicle cabin, the type and quality of the coating also change. Rail transit vehicles operate in C2-C5 environments, which determines that the coating must take into account both corrosion protection and decorative effects. In recent years, due to the fact that "base paint (including solid color base paint and metallic flash base paint) + overcoat clear paint" has better decorative effects than solid color topcoat paint, it has become the development direction of future rail transit vehicle supporting coatings. Metallic flash paint uses metallic aluminum powder pigments or pearl pigments. Among them, aluminum powder pigments are flaky in structure and can form several layers of parallel aluminum powder layers in the color paint layer, which has good reflectivity to ultraviolet light and can delay the aging damage of ultraviolet light to the coating. The aluminum powder layer has good shielding properties, preventing the penetration of water, gas and ions, thereby protecting the paint film. In addition, the parallel arrangement of the aluminum powder layer provides the entire coating with hiding power, color, metallic flash effect and "goniochromatic" effect, and has good decorative effects.

[0003] When the "water-based metallic flash base paint + overcoat clear paint" system for rail transit vehicles is applied, the metallic flash base paint and the overcoat clear paint are "wet-on-wet" applied. During the conversion process of water-based coatings, due to the influence of the volatilization rate of water-based paint, there are more factors than solvent-based paint, and problems such as aluminum powder blooming, poor aluminum powder arrangement, sagging, large color difference or poor interlayer adhesion are prone to occur. The inventors have found through extensive research that in order to achieve the corrosion protection and decorative effects of solvent-based supporting coatings through "wet-on-wet" application, the core difficulty is the "water-based metallic flash base paint". Therefore, in order to achieve the best silver powder arrangement, no blooming, no sagging, and good cooperation with the overcoat clear paint after "wet-on-wet" application of the water-based metallic flash base paint, it is necessary to find a water-based metallic flash base paint to meet the actual needs of the application of water-based metallic flash base paint in rail transit vehicle coating. SUMMARY

[0004] In view of the above problems, the present application provides a water-based metallic flash base paint, a preparation method and application thereof. Through the synergistic effect of each raw material component, the arrangement of the effect pigment aluminum powder is better, there is no blooming, no sagging, and good cooperation with the overcoat clear paint through "wet-on-wet" application, and the water-based metallic flash base paint has the advantages of metallic flash decoration and protection of the surface of the vehicle body from corrosion.

[0005] To solve the above technical problems, the technical solution provided by the present application is:

[0006] In a first aspect, the present application provides an aqueous metallic flash base paint, which is composed of A component and B component with a mass ratio of 100:(0-10).

[0007] The A component comprises raw material components in the following mass percentages: 10-20% of aqueous polycarbonate-containing aliphatic anionic polyurethane dispersion with a glass transition temperature of 40-50℃, 10-20% of aqueous aliphatic anionic polyurethane dispersion with a glass transition temperature of ≤5℃, 0-10% of aqueous self-crosslinking low-hydroxyl acrylate dispersion, 12-18% of aluminum powder slurry, 2-4% of aqueous cellulose acetate butyrate solution, 0.3-0.5% of surfactant, 0.3-1% of defoaming agent, 5-10% of effect pigment orienting agent, 1.5-5% of pH adjusting agent, 0.5-1.5% of wetting agent, 1-3% of thickening agent, 5-8% of first cosolvent, 18-22% of rheological aid, and 10-30% of water.

[0008] The B component comprises raw material components in the following mass percentages: 70-80% of curing agent and 20-30% of second cosolvent; the curing agent is at least one of hexamethylene diisocyanate or hydrophilic aliphatic polyisocyanate.

[0009] Compared with the prior art, the aqueous metallic flash base paint provided by the present application has the following advantages: the A component is the main paint component, and the B component is the curing component; the high-glass-transition-temperature aqueous polycarbonate-containing aliphatic anionic polyurethane dispersion and the low-glass-transition-temperature aqueous aliphatic anionic polyurethane dispersion are selected and compounded as the film-forming resin, and the aqueous self-crosslinking low-hydroxyl acrylate dispersion is selectively added; through specific proportioning and synergistic effect of the components, the characteristics of different types of aqueous resins are brought to the best state, so that the aqueous metallic flash base paint obtained finally has good gloss and thixotropy, the directional arrangement of aluminum powder is good when sprayed in a large area, there is no blooming, the edge joint (when sprayed in multiple passes) is good, the thixotropy is improved, and the flexibility and hardness of the cured film are balanced, thereby effectively solving the problem of difficult "wet-on-wet" matching coating construction in the "aqueous metallic flash base paint + clear topcoat" system.

[0010] The paint film prepared from the water-based polyurethane dispersion is soft, has a good thixotropic index and anti-sagging property, and a moderate drying speed; meanwhile, it has good permeability, and different spraying techniques have little effect on the color effect of the base paint, and the coating efficiency is high, and the adhesion to the upper and lower layers is also strong, and the paint film is in a good state of "not dry and not wet" when matched with a varnish, which can ensure good aluminum powder arrangement and interlayer adhesion, and the paint film is not easy to be "redissolved" by the varnish (when matched with the varnish by wet spraying, the auxiliary solvent in the varnish causes the base paint to be redissolved, so that the parallel oriented flaky pigment is reoriented, and a phenomenon of blackening and greying which can be observed by naked eyes is caused). The flexibility of the molecular chain is the most important factor to determine the glass transition temperature (Tg, referred to as glass temperature) of the polymer, and the better the flexibility of the main chain, the lower the glass temperature. It is found through a large number of experiments that the water-based polyurethane dispersion with a low glass temperature can still maintain good flexibility in a low-temperature environment, and can improve the film-forming property under low-temperature conditions; the water-based polyurethane dispersion with a high glass temperature can improve the adaptability of the paint in a high-temperature environment, and enhance the high-temperature resistance thereof; the water-based polyurethane dispersions with different glass temperatures are compounded, so that the paint film construction property under various complex conditions such as high temperature and low temperature can be adapted and improved, and a smooth and clean coating can be formed.

[0011] In addition, the water-based self-crosslinking low-hydroxyl acrylate dispersion has a high viscosity, a good thixotropic index and anti-sagging property due to the low content of hydroxyl groups in the molecule, more chemical bonds between molecules and more ordered arrangement between molecules; the lower the hydroxyl value, the worse the hydrophilicity, and the stronger the water resistance of the film after film formation. However, the water-based self-crosslinking low-hydroxyl acrylate dispersion and the water-based acrylic resin emulsion have the disadvantages of fast drying, poor interlayer adhesion and poor water resistance, and it is difficult to apply the paint by gun matching; and the paint film is easily dissolved or eroded by organic solvents, acids and bases, the volume shrinkage of the paint film is fast, the paint film has many pits and obvious particles, and the directional arrangement of aluminum powder is not good; meanwhile, the water-based metal flash base paint prepared from the water-based self-crosslinking low-hydroxyl acrylate dispersion has blue light or white light on the side, and it is difficult to adjust the color, and it cannot meet the requirements of large-area spraying and rapid color adjustment of the post-repair paint of the rail transit vehicle body. The water-based self-crosslinking low-hydroxyl acrylate dispersion is compounded in a certain proportion in the water-based polyurethane dispersion without hydroxyl groups, so that the hydroxyl groups (-OH) and the isocyanate (-NCO) curing agent can be chemically crosslinked, and the adhesion of the paint film is further enhanced; the synergistic effect of the water-based polyurethane dispersion and the water-based self-crosslinking low-hydroxyl acrylate dispersion can make up for the respective shortcomings of the water-based polyurethane dispersion and the water-based acrylic resin emulsion (the single water-based polyurethane dispersion has poor self-thickening property, low solid content, and poor water resistance, heat resistance and gloss of the paint film; the single water-based acrylic resin emulsion has poor heat adhesion, cold brittleness, poor flexibility, poor solvent resistance and color adjustment).

[0012] The water-based metal flash base paint has excellent comprehensive performance through the synergistic effect and specific proportioning content of the raw material components. The results of examples show that the water-based metal flash base paint has excellent sulfur hanging resistance, color joint capacity and interlayer adhesion without affecting the construction fluidity, the aluminum powder is arranged flat and delicate, the front metal feeling is strong, the side is deep, the color degree is higher when toning, and the water-based metal flash base paint has high practical value and popularization value.

[0013] Preferably, the solid content of the water-based polycarbonate-containing aliphatic anionic polyurethane dispersion with a glass transition temperature of 40-50℃, the water-based aliphatic anionic polyurethane dispersion with a glass transition temperature ≤5℃ and the water-based self-crosslinking low-hydroxyl acrylate dispersion is 34%-41%.

[0014] Preferably, the hydroxyl content of the water-based self-crosslinking low-hydroxyl acrylate dispersion is 1%-2%.

[0015] Preferably, the water-based polycarbonate-containing aliphatic anionic polyurethane dispersion with a glass transition temperature of 40-50℃ is Covestro Bayhydol UH 2606.

[0016] Preferably, the water-based self-crosslinking low-hydroxyl acrylate dispersion is Covestro Bayhydrol A 2846.

[0017] Preferably, the water-based aliphatic anionic polyurethane dispersion with a glass transition temperature ≤5℃ is at least one of Covestro Bayhydrol UH 2648 / 1, Covestro Bayhydrol UH 2110, Covestro Bayhydrol UH 2621 or Covestro Bayhydrol UH 2952 / 1.

[0018] The aliphatic anionic polyurethane dispersion has the advantages of light color, high transparency, good compatibility, slightly slow drying speed, relatively soft paint film, moderate film volume shrinkage, strong corrosion resistance, no chemical reaction with aluminum powder, and strong interlayer adhesion, etc., can minimize the interference on the color of the wet paint film, has the required rapid toning property of a repair paint, has excellent leveling property, chemical resistance and weather resistance after film formation, and has high toughness and good elasticity. The water-based aliphatic anionic polyurethane dispersion with low glass transition temperature (especially Covestro Bayhydrol UH 2952 / 1) and the water-based aliphatic anionic polyurethane dispersion containing polycarbonate with high glass transition temperature (Covestro Bayhydol UH 2606) can be attached to the surface of the vehicle body (or the surface of the OEM product) without polishing, has excellent adhesion and chemical resistance, can not only meet the needs of large-area spraying of the whole vehicle body of the rail transit vehicle, but also has good cooperation with the wet-on-wet top varnish, is especially suitable for repairing paint under the infrared baking lamp, or can be used to coat the two-component polyurethane varnish on the metal base paint layer after pre-baking. The resin with low hydroxyl value (water-based self-crosslinking low-hydroxyl acrylate dispersion) has high viscosity due to the less content of the internal hydroxyl group, more chemical bonds between the molecules, and more ordered arrangement between the molecules. In addition, the lower the hydroxyl value, the worse the hydrophilicity, and the stronger the water resistance after film formation. Adding a certain amount of the resin with low hydroxyl value to the film-forming resin can improve the thixotropic index and anti-sagging property of the paint.

[0019] Preferably, the aluminum powder slurry includes 6-8% of aluminum powder, 0.1-0.5% of dispersant (further preferably 0.3-0.5%) and 6-10% of medium solution, based on 100% of the A component.

[0020] Further preferably, the aluminum powder is at least one of Eka Hydrolan-501, Eka Hydrolan-2154 or Eka Hydrolan-214.

[0021] For example, the particle size of Eka Hydrolan-501 is 21 μm, the particle size of Eka Hydrolan-2154 is 18 μm, and the particle size of Eka Hydrolan-214 is 32 μm.

[0022] More preferably, the aluminum powder is at least two of Eka Hydrolan-501, Eka Hydrolan-2154 or Eka Hydrolan-214.

[0023] The application uses aluminum powders with different particle sizes to balance the flash effect and hiding power index. The large-particle-size aluminum powder and the small-particle-size aluminum powder are compounded in a proper ratio to make up for each other's shortcomings and achieve the effect of balancing the performance of the coating film hiding power, flashiness, and fresh reflection, etc.

[0024] Further preferably, the dispersant is at least one of BYK-192, DISPERBYK-180, BYK-2012, BYK-2013, Dispers-655, Tego-656, BYK-345, polyvinylpyrrolidone (PVP), N,N-dimethylformamide (DMF) or polyvinyl alcohol.

[0025] More preferably, the dispersant comprises a first dispersant and a second dispersant in a mass ratio of 1:(0.5-1); the first dispersant is at least one of BYK-192, DISPERBYK-180, BYK-2012, BYK-2013, Dispers-655 or Tego-656, and the second dispersant is at least one of BYK-345, polyvinylpyrrolidone (PVP), N,N-dimethylformamide (DMF) or polyvinyl alcohol.

[0026] In the present application, the specific dispersant is combined with the aluminum powder through π-π bond, and can be uniformly dispersed in the aluminum powder slurry, further promoting the uniform dispersion of the aluminum powder.

[0027] Further preferably, the medium solution is at least one of an aqueous ethylene glycol butyl ether solution, an aqueous propylene glycol methyl ether solution, an aqueous dipropylene glycol dimethyl ether solution, an aqueous N-methyl pyrrolidone solution, an aqueous dimethyl sulfoxide solution, an aqueous dimethylformamide solution, an aqueous N-methylformamide solution or an aqueous tetrahydrofuran solution.

[0028] More preferably, the mass concentration of the medium solution is 50%-75%.

[0029] More preferably, the medium solution is an aqueous ethylene glycol butyl ether solution with a mass concentration of 50%-75%.

[0030] More preferably, the medium solution is composed of a first medium, a second medium and water in a mass ratio of 2:(1-2):3; the first medium is ethylene glycol butyl ether (BCS) or dipropylene glycol dimethyl ether (DMM), and the second medium is N-methyl pyrrolidone (NMP), dimethyl sulfoxide (DMSO), dimethylformamide (DMF), N-methylformamide (NMF) or tetrahydrofuran (THF).

[0031] In the present application, the specific medium has excellent stability, fluidity and solubility, can significantly reduce the surface tension of the aluminum powder slurry, plays the role of an auxiliary leveling agent, and improves the spreadability and adhesion of the coating; by compounding the first cosolvent, the particles of the aluminum powder can be made more uniform, the liquid mixture is stabilized, the aluminum powder is better dissolved in water, and the aluminum powder is better oriented.

[0032] Preferably, the method for preparing the aluminum paste comprises the following steps:

[0033] The dispersant and the aluminum powder are added into the medium solution and mixed uniformly to obtain the aluminum paste.

[0034] For example, the dispersant is first added into the medium solution, stirred at a low speed (200-300 rpm) for 3-5 min, then the aluminum powder is added, and stirred at a low speed for 10-20 min to obtain the aluminum paste.

[0035] Preferably, the first co-solvent is at least two of a dipropylene glycol methyl ether aqueous solution, a glycol butyl ether aqueous solution, a diethylene glycol monobutyl ether aqueous solution, or a propylene glycol methyl ether propylene carbonate aqueous solution.

[0036] Preferably, the mass concentration of the first co-solvent is 50%-75%.

[0037] Further preferably, the first co-solvent is composed of equal mass of glycol butyl ether (BCS), diethylene glycol monobutyl ether (BDG), and water, or composed of equal mass of glycol butyl ether (BCS), propylene glycol methyl ether propylene carbonate (PMP), and water, or composed of equal mass of glycol butyl ether (BCS), dipropylene glycol methyl ether (DPM), propylene glycol methyl ether propylene carbonate (PMP), and water.

[0038] In the present application, the specific first co-solvent has good solubility, can couple different phases, and is miscible with various hydrophilic and hydrophobic solvents, which helps to reduce the surface tension of the aqueous system, enhance the flowability of the coating, and thus improve the wettability and coating effect of the coating, so as to form a uniform and smooth coating; by compounding first co-solvents with different boiling points (gradient boiling points), the balance of the evaporation speed is facilitated during the film forming process, the solubility in water is improved, and thus the orientation of the aluminum powder is more facilitated.

[0039] Preferably, the pH regulator is a 8wt%-12wt% dimethyl ethanolamine aqueous solution.

[0040] Preferably, the aqueous cellulose acetate butyrate solution comprises, based on 100% of the A component, 0.4%-0.6% of the aqueous cellulose acetate butyrate, 0-0.01% of the pH regulator, and 1.5%-3.5% of the medium solution.

[0041] Further preferably, the aqueous cellulose acetate butyrate is Eastman Solus 3050.

[0042] Preferably, the surfactant is gas chemical Surfynol 104BC.

[0043] In the present application, Surfynol 104BC is a non-ionic surface active agent of acetylenic diol, which can achieve static and dynamic surface tension balance due to its special structure, and has low water sensitivity, foam suppression, improved dispersibility, improved flow and leveling, and other effects, which can effectively reduce the surface tension of the coating, and stabilize the consistency and viscosity.

[0044] Preferably, the preparation method of the water-based cellulose acetate butyrate solution comprises the following steps:

[0045] The water-based cellulose acetate butyrate is added to the medium solution, mixed uniformly, and the pH value of the mixed solution is adjusted to 8-9 by using a pH adjuster, thereby obtaining the water-based cellulose acetate butyrate solution.

[0046] Preferably, the defoaming agent is at least one of BYK-011, BYK-028, BYK-093, Tego-810, Tego-903 or Surfynol 440.

[0047] Further preferably, the defoaming agent is equal mass of BYK-093 and Surfynol 440.

[0048] The defoaming agent provided by the present application has low dynamic tension and good compatibility.

[0049] Preferably, the effect pigment orientation agent is AQUATIX 8421.

[0050] Preferably, the wetting agent is at least one of BYK-345, BYK-347, BYK-348, BYK-349, Tego-4100 or Surfynol 104BC.

[0051] The dynamic surface tension of the wet film needs to be slightly lower than the surface tension of the substrate, so that the paint film can be well wetted with the substrate to form a continuous and stable paint film. In the present application, BYK-347, BYK-348, BYK-349 and Tego-4100 are all organosilicon surfactants (polyether modified siloxane), and the use of the above polyether modified siloxane in water-based paint can significantly reduce the surface tension of the paint and improve the substrate wettability of the system; in addition, BYK-347 also has excellent re-coatability; Surfynol 104BC is a non-ionic surface active agent of acetylenic diol, which can achieve static and dynamic surface tension balance due to its special structure, and has low water sensitivity, foam suppression, improved dispersibility, improved flow and leveling, and other effects, which can effectively reduce the surface tension of the coating, and stabilize the consistency and viscosity.

[0052] Preferably, the thickening agent is a polyurethane associated thickening agent.

[0053] Further preferably, the thickening agent is at least one of Rheolate 299, RheoByk-H 7625VF, or RM-8W.

[0054] In the present application, Rheolate 299 and RheoByk-H 7625VF are the same type of polyurethane associative thickening agent, which is not affected by pH value; Rheolate 299 can provide high thickening efficiency in the range of low and medium shear rate, and RheoByk-H 7625VF can sharply increase viscosity at low shear rate, playing a complementary role; RM-8W is a low odor, solvent-free aqueous non-ionic associative rheology modifier (hydrophobically modified polyurethane), which can provide excellent flow and leveling, uniform film formation, gloss development, and high thickening efficiency.

[0055] Preferably, the rheological aid includes 0.3% to 0.5% of organically modified synthetic layered silicate, 0.3% to 0.5% of emulsifying dispersant, and 17.5% to 21% of water, based on 100% of the A component.

[0056] Further preferably, the organically modified synthetic layered silicate is Laponite-RD.

[0057] Further preferably, the emulsifying dispersant is at least one of polyethylene glycol or polypropylene glycol. If the emulsifying dispersant includes polyethylene glycol and polypropylene glycol, the mass ratio of polyethylene glycol to polypropylene glycol can be 1:1.

[0058] More preferably, the emulsifying dispersant is at least one of PEG-1000, PEG-1500, PPG-200, PPG-400, or PPG-600.

[0059] In the present application, the rheological aid can play an active regulating role in anti-sagging. The amount of this component is related to the construction temperature, and the higher the construction temperature, the more the amount.

[0060] Preferably, the preparation method of the rheological aid includes the following steps:

[0061] The emulsifying dispersant is added to water and mixed uniformly, and then the organically modified synthetic layered silicate is added and mixed uniformly to obtain the rheological aid.

[0062] For example, under the condition of stirring at 400 to 600 rpm, the emulsifying dispersant is added to water, the stirring speed is adjusted to 1000 to 1500 rpm, the organically modified synthetic layered silicate is slowly added, and the stirring is continued until the solution is clear and no undissolved particles are observed, thereby obtaining the rheological aid.

[0063] Preferably, the solid content of the A component is 15% to 30%, and more preferably 20% to 25%.

[0064] In the present application, the solid content of the A component refers to the mass proportion of all solid components in the A component.

[0065] Preferably, the curing agent comprises 25% to 30% of low-viscosity hydrophobic hexamethylene diisocyanate, 25% to 30% of high-viscosity hydrophilic hexamethylene diisocyanate, and 18% to 22% of hydrophilically modified isophorone diisocyanate, based on 100% of the B component.

[0066] It should be noted that the hydrophilically modified isophorone diisocyanate in the present application refers to a hydrophilically modified aliphatic polyisocyanate based on isophorone diisocyanate (IPDI).

[0067] Further preferably, the low-viscosity hydrophobic hexamethylene diisocyanate is at least one of Covestro Desmodur N3900, Covestro Desmodur N3600, or Wanhua WANNATE HT-600.

[0068] Further preferably, the high-viscosity hydrophilic hexamethylene diisocyanate is at least one of Covestro Bayhydrol XP2655, Covestro Bayhydur XP 2547, Covestro Bayhydur XP 2487 / 1, Covestro Bayhydur 304, or Covestro Bayhydur 305.

[0069] Preferably, the solid content of the hydrophilic aliphatic polyisocyanate is 60% to 70%.

[0070] Preferably, the -NCO content of the hydrophilic aliphatic polyisocyanate is 8.5% to 9.5%.

[0071] Further preferably, the hydrophilic aliphatic polyisocyanate is at least one of Covestro Bayhydur 401-70 or Covestro Bayhydur 401-60.

[0072] The present application can further improve the curing effect, and improve the construction fluidity, viscosity, and gloss of the coating by limiting the type of curing agent.

[0073] Preferably, the second co-solvent is at least one of propylene glycol methyl ether acetate (PMA), propylene glycol methyl ether acrylate (PMP), propylene carbonate (PC), propylene glycol diacetate (PGDA), ethylene glycol butyl ether acetate (BGA), dibasic ester (DBE), or dipropylene glycol dimethyl ether (DMM).

[0074] The present application adds a certain amount of second cosolvent in the curing component, which can improve the compatibility of the curing agent and the water-based self-crosslinking low-hydroxyl acrylate dispersion, and can also prolong the open time of the paint film, which is beneficial to leveling. The specific second cosolvent is an environmentally friendly solvent, which has the following characteristics: (1) containing multiple functional groups, it has strong solubility to polar and non-polar substances, which can improve the film strength; (2) having low surface tension, strong solvent power, low viscosity and good volatility, which can provide good solubility and flowability, ensure uniform coating, easy construction, and at the same time, improve the adhesion and durability of the coating, adjust the evaporation rate of the whole system, adjust the drying speed of the paint film, reduce pinholes and fish eyes, and increase gloss, wetting, leveling and re-leveling; (3) propylene carbonate has good film-forming property and strong carbon dioxide absorption capacity, and when used with a hydrophilic isocyanate curing agent, the effect is excellent, which can improve the blister and reduce the bubbles; (4) the use of multiple second cosolvents can complement each other to achieve better comprehensive effect. In addition, by compounding second cosolvents with different boiling points (gradient boiling points), it is beneficial to balance the evaporation rate during film formation, improve the solubility in water, and further facilitate the orientation of aluminum powder. For example, the synergistic effect of propylene glycol methyl ether acetate (PMA), propylene glycol methyl ether propionate (PMP) and propylene carbonate (PC) can not only improve the film strength, but also be beneficial to the stable storage of the coating, and can also absorb carbon dioxide during coating and film formation, and the effect of diluting the water-based isocyanate curing agent is excellent.

[0075] It should be noted that the curing agent is not diluted with propylene glycol diacetate (PGDA), because dilution with PGDA will have an adverse effect on the orientation of aluminum powder.

[0076] Preferably, the mass ratio of the A component to the B component is 100:(0-5).

[0077] Preferably, when the A component contains the water-based self-crosslinking low-hydroxyl acrylate dispersion, the molar ratio of -NCO to -OH is (1.2-1.5):1.

[0078] It should be noted that when the A component does not contain the water-based self-crosslinking low-hydroxyl acrylate dispersion, the curing component can not be added.

[0079] In the second aspect, the present application provides a preparation method of a water-based metal flash base paint, which comprises the following steps:

[0080] S1, according to the design ratio, each raw material is weighed, the aluminum powder slurry is placed for 20-40 min, then the water-based cellulose acetate butyrate solution, the surfactant and the defoaming agent are added into the aluminum powder slurry, and the mixture is uniformly mixed and placed for 1.5-2.5 h; the water-based polycarbonate aliphatic anionic polyurethane dispersion with a glass transition temperature of 40-50 ℃ is added into the system, and the mixture is uniformly mixed, and the pH of the system is adjusted to 9-9.5 by using a pH adjuster; then the wetting agent, the effect pigment directional agent, the first part of water and the thickening agent are added, the mixture is uniformly mixed, the pH of the system is adjusted to 8-8.5 by using a pH adjuster, and a first mixed system is obtained;

[0081] S2, the water-based aliphatic anionic polyurethane dispersion with a glass transition temperature of ≤5 ℃ and the water-based self-crosslinking low-hydroxy acrylate dispersion are added into the second part of water, the mixture is uniformly mixed, the pH of the system is adjusted to 8-8.5 by using a pH adjuster, and then the first cosolvent is added, and a second mixed system is obtained;

[0082] S3, the second mixed system and the rheological aid are added into the first mixed system, the mixture is uniformly mixed, and an A component is obtained;

[0083] S4, the curing agent is added into the second cosolvent, the mixture is uniformly mixed, and a B component is obtained.

[0084] It should be noted that the steps S1 and S2 have no sequence, and the A component and the B component also have no sequence.

[0085] For example, according to needs, the mass of the first part of water accounts for 0-15% of the mass of the A component, and the mass of the second part of water accounts for 10%-20% of the mass of the A component.

[0086] In the preparation method of the water-based metal flash base paint provided by the application, the addition of the effect pigment directional agent and other substances in step S1 can reduce the pH value of the mixed system, and therefore the pH value of the system needs to be adjusted to a specific alkaline environment by using a pH adjuster before the addition of the effect pigment directional agent, so as to further ensure the storage stability of the paint. In addition, the aluminum powder slurry is added before the addition of the effect pigment directional agent, and the step of diluting the effect pigment directional agent with water is omitted.

[0087] The pH value of the coating is too low to cause acidification, which not only reduces the solubility of the resin in the mixed system, resulting in precipitation of the resin, but also causes esterification reaction between alcohol and acid in the mixed system, and most of the generated esters are insoluble in water, which further accelerates the precipitation of the resin, thereby seriously reducing the physical properties of the coating (for example, the viscosity suddenly increases, and plugging occurs). The present application finds through a large number of tests that the stability of the coating is best when the pH value of the mixed system (including the first mixed system, the second mixed system and the A component) is set to 8-8.5, and no stratification, precipitation, flocculation, and pigment agglomeration occur.

[0088] In a third aspect, the present application provides the use of the above-mentioned water-based metallic flash base paint in a vehicle coating.

[0089] Preferably, the vehicle coating is a rail transit vehicle coating.

[0090] Preferably, the use method of the water-based metallic flash base paint comprises the following steps:

[0091] Mixing the A component and the B component uniformly, adding an activating diluent, mixing uniformly, obtaining a construction coating with a solid content of 15%-17%, and uniformly coating on a metal substrate or a basecoat paint.

[0092] It should be noted that if the water-based metallic flash base paint does not contain the B component, only the activating diluent is added to the A component and mixed uniformly.

[0093] The inventors find through a large number of tests that under the same construction spraying number, when the solid content of the construction coating is 12%-15%, the rapid evaporation of the solvent material after application promotes the orientation of the aluminum powder, the flash index of the coating is higher, the aluminum powder arrangement is good, but the dry film thickness is slightly lower, and the hiding power is poorer. If the construction spraying number is increased to achieve a suitable dry film thickness and hiding power, the already parallel oriented aluminum sheets will be re-oriented (such as translation), which not only leads to poor orientation of the aluminum powder, but also causes rough coating and reduced brightness after polishing, forming a black and gray phenomenon visible to the naked eye. The present application controls the solid content of the construction coating to 15%-17%, which can ensure that the comprehensive effects of the paint film, dry film thickness, hiding power, flash index and construction are in the best state, and spraying 2-3 times can control the dry film thickness to 12-15 μm, while ensuring that the paint film is smooth and delicate, the aluminum powder arrangement is good, the hiding power is good, and the construction does not sag.

[0094] Further preferably, the activating diluent comprises the following mass percentage of raw material components: water-based cellulose acetate butyrate solution 15%-25%, effect pigment orientation agent 3.5%-4.5%, rheological aid 1.5%-2.5%, and water 68%-80%, and the sum of each component is 100%.

[0095] In the method for using the water-based metallic flash base paint, the water-based metallic flash base paint (A component+B component) is diluted by using a unique activation diluent, and the following beneficial effects are achieved: (1) improving the tolerance of the system to high content of surfactants or extreme pH value; (2) preventing the paint from sagging or dissolving during the “wet-on-wet” construction; (3) accelerating the formation of the structure after the construction, so as to realize the directional anti-sagging of the ideal effect pigment (aluminum powder), promote the directional arrangement of the effect pigment, improve the adhesion of the vertical surface (improve the interlayer adhesion between the water-based metallic flash base paint and the overcoat varnish), and prevent the overcoat varnish from “back dissolving”.

[0096] Further preferably, the mass ratio of the A component to the activation diluent is 100:(0-50).

[0097] The application can ensure that the solid content of the construction paint is 15%-17% by using the above mass ratio.

[0098] More preferably, the water-based cellulose acetate butyrate solution comprises the following raw material components in the following mass percentages: 15%-25% of water-based cellulose acetate butyrate, 0-0.5% of a pH adjuster, and 74.5%-85% of a medium solution, and the sum of the components is 100%.

[0099] For example, the water-based cellulose acetate butyrate is Eastman Solus 3050.

[0100] For example, the pH adjuster is a 8wt%-12wt% dimethyl ethanolamine aqueous solution, which is used to adjust the pH of the water-based cellulose acetate butyrate solution to 8-9.

[0101] For example, the medium solution is at least one of the following: an ethylene glycol butyl ether aqueous solution, a propylene glycol methyl ether aqueous solution, a dipropylene glycol dimethyl ether aqueous solution, an N-methyl pyrrolidone aqueous solution, a dimethyl sulfoxide aqueous solution, a dimethyl formamide aqueous solution, an N-methyl formamide aqueous solution, or a tetrahydrofuran aqueous solution; and the mass concentration of the medium solution is 50%-75%.

[0102] For example, the medium solution is a 50%-75% ethylene glycol butyl ether aqueous solution.

[0103] For example, the medium solution is composed of a first medium, a second medium, and water in a mass ratio of 2:(1-2):3; the first medium is ethylene glycol butyl ether (BCS) or dipropylene glycol dimethyl ether (DMM), and the second medium is N-methyl pyrrolidone (NMP), dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), N-methyl formamide (NMF), or tetrahydrofuran (THF).

[0104] In an example, the effect pigment orienting agent is BYK AQUATIX 8421.

[0105] More preferably, the rheological aid includes the following mass percentage of raw material components: organic modified synthetic layered silicate 1.5% to 2.5%, emulsifying dispersant 1.5% to 2.5%, and water 95% to 97%, and the sum of each component is 100%.

[0106] In an example, the organic modified synthetic layered silicate is BYK Laponite-RD.

[0107] In an example, the emulsifying dispersant is at least one of polyethylene glycol or polypropylene glycol. If the emulsifying dispersant includes polyethylene glycol and polypropylene glycol, the mass ratio of polyethylene glycol and polypropylene glycol can be 1:1.

[0108] In an example, the emulsifying dispersant is at least one of PEG-1000, PEG-1500, PPG-200, PPG-400, or PPG-600.

[0109] It should be noted that the raw material components and proportions of the aqueous cellulose acetate butyrate solution and the rheological aid in the present application activating diluent can be completely the same as those of the aqueous cellulose acetate butyrate solution and the rheological aid in the A component.

[0110] In the present application, the rheological aid can increase the low shear viscosity of the coating, prevent the coating from sagging or melting during "wet-on-wet" construction, further improve the workability and storage stability of the coating, and effectively prevent the settlement of solid materials and the shrinkage of the water-based coating system; in addition, the pH value does not need to be adjusted during the addition process, and the formula with pH value from strong acid to strong base is effective, especially suitable for large-area construction spraying of rail transit vehicle body, accelerating the formation of structure after construction, thereby realizing ideal aluminum powder orientation. The rheological property can also effectively prevent the precipitation of the base paint and improve the stability. The rheological aid, the effect pigment orienting agent, and the aqueous cellulose acetate butyrate solution can form a synergistic effect, enhance the orientation of aluminum powder, improve the adhesion of the water-based metal flash base paint on the vertical surface, further improve the interlayer adhesion of the water-based metal flash base paint and the overcoat clear paint, and further prevent the "back dissolution" of the overcoat clear paint.

[0111] The present application finds through a large number of tests that when the rheological aid is compounded with the effect pigment orienting agent, too much rheological aid will result in poor water resistance of the water-based metal flash base paint; when the rheological aid is compounded with the aqueous cellulose acetate butyrate solution, too much aqueous cellulose acetate butyrate solution will also result in poor water resistance of the water-based metal flash base paint; when the rheological aid is compounded with the effect pigment orienting agent and the aqueous cellulose acetate butyrate solution in a specific ratio, the storage stability and water resistance of the coating can be further improved, and the orientation of aluminum powder is promoted, so that the appearance of the paint film reaches the best state. DETAILED DESCRIPTION

[0112] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to examples. It should be understood that the specific examples described herein are only used to explain the present application and not intended to limit the present application.

[0113] The present application provides an aqueous metallic flash base paint, which is composed of A component and B component with a mass ratio of 100:(0-10); wherein,

[0114] The A component comprises the following raw material components with the following mass percentages: 10-20% of aqueous polycarbonate aliphatic anionic polyurethane dispersion with a glass transition temperature of 40-50℃, 10-20% of aqueous aliphatic anionic polyurethane dispersion with a glass transition temperature ≤5℃, 0-10% of aqueous self-crosslinking low-hydroxyl acrylate dispersion, 12-18% of aluminum paste (6-8% of aluminum powder, 0.1-0.5% of dispersant and 6-10% of medium solution), 2-4% of aqueous cellulose acetate butyrate solution (0.4-0.6% of aqueous cellulose acetate butyrate, 0-0.01% of pH regulator and 1.5-3.5% of medium solution), 0.3-0.5% of surfactant, 0.3-1% of defoaming agent, 5-10% of effect pigment orienting agent, 1.5-5% of pH regulator, 0.5-1.5% of wetting agent, 1-3% of thickening agent, 5-8% of first cosolvent, 18-22% of rheological aid (0.3-0.5% of organic modified synthetic layered silicate, 0.3-0.5% of emulsifying dispersant and 17.5-21% of water) and 10-30% of water;

[0115] The B component comprises the following raw material components with the following mass percentages: 70-80% of curing agent and 20-30% of second cosolvent; the curing agent is at least one of hexamethylene diisocyanate or hydrophilic aliphatic polyisocyanate.

[0116] The water used in the examples of the present application is all deionized water. It should be noted that in the aqueous cellulose acetate butyrate solution of the present application, the pH regulator functions to adjust the pH value of the aqueous cellulose acetate butyrate solution, and since the amount of the pH regulator is very small, the mass of the pH regulator in the aqueous cellulose acetate butyrate solution in the examples of the present application can be negligible.

[0117] The test instruments used in the present application include:

[0118] Ruler, Guangzhou Biao Ge Da;

[0119] Pencil hardness meter, impact instrument, bending tester, cupping tester, sharpness tester, Germany BYK;

[0120] MA85 multi-angle spectrophotometer, X-Rite, USA;

[0121] ISO 6 cup, 4# cup, solvent resistance wiper, pH meter, film thickness meter, Shanghai Modern Environmental Engineering Technology Co., Ltd.;

[0122] Salt spray resistance tester, artificial climate aging resistance (QUA / SPARY), Q-Lab, USA.

[0123] In order to better illustrate the present application, the following is further illustrated by examples.

[0124] Example 1

[0125] The present example provides a water-based metallic flash basecoat, which is composed of a component A and a component B with a mass ratio of 100:0.5. Among them,

[0126] The component A is composed of raw material components with the following mass percentages: Covestro Bayhydol UH 2606 13%, water-based aliphatic anionic polyurethane dispersion with a glass transition temperature ≤ 5 ℃ (denoted as PUD with Tg≤5) 14%, Covestro Bayhydrol A 2846 3%, aluminum paste 14.8% (aluminum powder 7%, dispersant 0.3% and medium solution 7.5%), water-based cellulose acetate butyrate solution 2.5% (denoted as CAB solution, Eastman Solus 3050 0.5%, medium solution 2%, pH = 8.5), gas chemical Surfynol 104BC 0.4%, defoamer 0.6%, BYK AQUATIX 8421 6%, 10 wt% aqueous dimethyl ethanolamine solution 2.4%, wetting agent 1%, thickening agent 2%, first cosolvent 6%, rheological aid 19.3% (BYK Laponite-RD 0.4%, emulsifying dispersant 0.4% and water 18.5%) and water 15%.

[0127] The component B is composed of raw material components with the following mass percentages: curing agent 75% (low viscosity hydrophobic hexamethylene diisocyanate 28%, high viscosity hydrophilic hexamethylene diisocyanate 27% and hydrophilic modified isophorone diisocyanate 20%) and second cosolvent 25%.

[0128] The specific components of the above raw materials are shown in Table 1. It is calculated that the solid content of the component A is 21.1%.

[0129] The preparation method of the above water-based metallic flash basecoat includes the following steps:

[0130] S1, each raw material was weighed according to the designed ratio, the aluminum paste was allowed to stand for 30 min, then the water-based cellulose acetate butyrate solution, the gas chemical Surfynol 104BC and the defoaming agent were added into the aluminum paste, and the mixture was uniformly mixed and allowed to stand for 2 h; the Covestro Bayhydol UH 2606 was added into the system, the mixture was uniformly mixed, and the pH of the system was adjusted to 9 by using a 10 wt% dimethyl ethanolamine aqueous solution; then the wetting agent, the BYK AQUATIX 8421, the first part of water and the thickening agent were added, the mixture was uniformly mixed, the pH of the system was adjusted to 8.5 by using a 10 wt% dimethyl ethanolamine aqueous solution, and a first mixed system was obtained.

[0131] S2, the water-based aliphatic anionic polyurethane dispersion with a glass transition temperature of ≤5 ℃ and the Covestro Bayhydrol A2846 were added into the second part of water, the mixture was uniformly mixed, the pH of the system was adjusted to 8.5 by using a 10 wt% dimethyl ethanolamine aqueous solution, and a second mixed system was obtained.

[0132] S3, the above-mentioned second mixed system and the rheological aid were added into the above-mentioned first mixed system, the mixture was uniformly mixed, and an A component was obtained.

[0133] S4, the curing agent was added into the second cosolvent, the mixture was uniformly mixed, and a B component was obtained.

[0134] Example 2

[0135] The present example provides a water-based metallic flash basecoat, which is composed of an A component. Wherein,

[0136] The A component is composed of raw material components with the following mass percentages: Covestro Bayhydol UH 2606 19%, water-based aliphatic anionic polyurethane dispersion with a glass transition temperature of ≤5 ℃ 13%, aluminum paste 14.2% (aluminum powder 6%, dispersant 0.2% and medium solution 8%), water-based cellulose acetate butyrate solution 2.1% (Eastman Solus 3050 0.4%, medium solution 1.7%, pH = 8.5), gas chemical Surfynol 104BC 0.3%, defoaming agent 0.4%, BYK AQUATIX 8421 6%, 12 wt% dimethyl ethanolamine aqueous solution 1.7%, wetting agent 0.5%, thickening agent 1.2%, first cosolvent 6%, rheological aid 19.6% (BYK Laponite-RD 0.3%, emulsifying dispersant 0.3% and water 19%) and water 16%.

[0137] The specific components of the above-mentioned raw materials are shown in Table 1. It is calculated that the solid content of the A component is 19.8%.

[0138] The preparation method of the above-mentioned water-based metallic flash basecoat comprises the following steps:

[0139] S1, each raw material was weighed according to the designed ratio, the aluminum paste was allowed to stand for 40 min, then the aqueous cellulose acetate butyrate solution, the gas chemical Surfynol 104BC and the defoaming agent were added into the aluminum paste, and the mixture was uniformly mixed and allowed to stand for 2.5 h; the Cognis Bayhydol UH 2606 was added into the system, and the mixture was uniformly mixed, the pH of the system was adjusted to 9 with 10 wt% dimethyl ethanolamine aqueous solution; then the wetting agent, the BYK AQUATIX 8421, the first part of water and the thickening agent were added, the mixture was uniformly mixed, the pH of the system was adjusted to 8 with 10 wt% dimethyl ethanolamine aqueous solution, and a first mixed system was obtained.

[0140] S2, the aqueous aliphatic anionic polyurethane dispersion with a glass transition temperature ≤ 5 ℃ was added into the second part of water, and the mixture was uniformly mixed, the pH of the system was adjusted to 8 with 10 wt% dimethyl ethanolamine aqueous solution, and then the first co-solvent was added, and a second mixed system was obtained.

[0141] S3, the above second mixed system and the rheological aid were added into the above first mixed system, and the mixture was uniformly mixed, and a component A, i.e. the aqueous metallic flash base paint, was obtained.

[0142] Example 3

[0143] The present example provides an aqueous metallic flash base paint, which is composed of a component A and a component B with a mass ratio of 100:1.7. Wherein,

[0144] The component A is composed of raw material components with the following mass percentages: Cognis Bayhydol UH 2606 11%, aqueous aliphatic anionic polyurethane dispersion with a glass transition temperature ≤ 5 ℃ 18%, Cognis Bayhydrol A 2846 10%, aluminum paste 13.2% (aluminum powder 6.5%, dispersant 0.2% and medium solution 6.5%), aqueous cellulose acetate butyrate solution 2% (Eastman Solus 3050 0.5%, medium solution 1.5%, pH = 8.5), gas chemical Surfynol 104BC 0.3%, defoaming agent 0.4%, BYK AQUATIX 8421 6%, 10 wt% dimethyl ethanolamine aqueous solution 2%, wetting agent 0.5%, thickening agent 1.5%, first co-solvent 5.4%, rheological aid 18.7% (BYK Laponite-RD 0.35%, emulsifying dispersant 0.35% and water 18%) and water 11%.

[0145] The component B is composed of raw material components with the following mass percentages: curing agent 73% (low viscosity hydrophobic hexamethylene diisocyanate 30%, high viscosity hydrophilic hexamethylene diisocyanate 25% and hydrophilic modified isophorone diisocyanate 18%) and second co-solvent 27%.

[0146] The specific components of each raw material are shown in Table 1. The solid content of the A component is calculated to be 23.3%.

[0147] The preparation method of the above-mentioned water-based metallic flash base paint comprises the following steps:

[0148] S1, according to the designed ratio, each raw material was weighed, the aluminum powder slurry was allowed to stand for 20 min, then the water-based cellulose acetate butyrate solution, the gas chemical Surfynol 104BC and the defoaming agent were added into the aluminum powder slurry, and mixed uniformly, and allowed to stand for 1.5 h; the Cognis Bayhydol UH 2606 was added into the system, mixed uniformly, and the pH of the system was adjusted to 9.5 with 10 wt% dimethyl ethanolamine aqueous solution; then the wetting agent, the BYK AQUATIX 8421, the first part of water and the thickening agent were added, mixed uniformly, and the pH of the system was adjusted to 8.5 with 10 wt% dimethyl ethanolamine aqueous solution, to obtain a first mixed system.

[0149] S2-S4, same as Example 1, which will not be repeated.

[0150] Example 4

[0151] The present example provides a water-based metallic flash base paint, which is composed of an A component and a B component with a mass ratio of 100:0.1. Wherein,

[0152] The A component is composed of raw material components with the following mass percentages: Cognis Bayhydol UH 2606 10%, water-based aliphatic anionic polyurethane dispersion with a glass transition temperature ≤ 5℃ 12%, Cognis Bayhydrol A 2846 0.7%, aluminum powder slurry 12.5% (aluminum powder 6%, dispersant 0.5% and medium solution 6%), water-based cellulose acetate butyrate solution 3.9% (Eastman Solus 3050 0.4%, medium solution 3.5%, pH = 8.5), gas chemical Surfynol 104BC 0.5%, defoaming agent 0.3%, BYK AQUATIX 8421 5%, 12 wt% dimethyl ethanolamine aqueous solution 1.5%, wetting agent 0.5%, thickening agent 3%, first cosolvent 5%, rheological aid 18.1% (BYK Laponite-RD 0.3%, emulsifying dispersant 0.3% and water 17.5%) and water 27%.

[0153] The B component is composed of raw material components with the following mass percentages: curing agent 80% (low viscosity hydrophobic hexamethylene diisocyanate 28%, high viscosity hydrophilic hexamethylene diisocyanate 30% and hydrophilic modified isophorone diisocyanate 22%) and second cosolvent 20%.

[0154] The specific components of each raw material are shown in Table 1. The solid content of the A component is calculated to be 23.3%.

[0155] The preparation method of the above-mentioned water-based metallic flash base paint is the same as that of Example 1, and will not be repeated here.

[0156] Example 5

[0157] This example provides a water-based metallic flash base paint, which is composed of Component A. Among them,

[0158] Component A is composed of raw material components with the following mass percentages: Covestro Bayhydol UH 2606 11.1%, water-based aliphatic anionic polyurethane dispersion with a glass transition temperature of ≤5°C 10%, aluminum powder slurry 18% (aluminum powder 8%, dispersant 0.1%, and medium solution 9.9%), water-based cellulose acetate butyrate solution 2.1% (Eastman Solus 3050 0.6%, medium solution 1.5%, pH = 8.5), gas chemical Surfynol 104BC 0.3%, defoaming agent 1%, BYK AQUATIX 8421 10%, 8wt% dimethyl ethanolamine aqueous solution 5%, wetting agent 1.5%, thickening agent 1%, first cosolvent 8%, rheological aid 22% (BYK Laponite-RD 0.5%, emulsifying dispersant 0.5%, and water 21%), and water 10%.

[0159] The specific components of the above-mentioned raw materials are shown in Table 1. It is calculated that the solid content of Component A is 20.3%.

[0160] The preparation method of the above-mentioned water-based metallic flash base paint is the same as that of Example 2, and will not be repeated here.

[0161] Example 6

[0162] This example provides a water-based metallic flash base paint, which is similar to Example 1, except that the aluminum powder in the aluminum powder slurry is all Elcan Hydrolan-501, and the curing agent is all Covestro Desmodur N3900. The remaining components are the same as those in Example 1, and will not be repeated here.

[0163] The preparation method of the above-mentioned water-based metallic flash base paint is the same as that of Example 1, and will not be repeated here.

[0164] Example 7

[0165] This example provides a water-based metallic flash base paint, which is similar to Example 1, except that the aluminum powder in the aluminum powder slurry is all Elcan Hydrolan-2154, and the curing agent is all Covestro Bayhydrol XP 2655. The remaining components are the same as those in Example 1, and will not be repeated here.

[0166] The preparation method of the above-mentioned water-based metallic flash base paint is the same as that of Example 1, and will not be repeated here.

[0167] Example 8

[0168] This example provides a waterborne metallic flash basecoat similar to Example 1, except that the aluminum powder in the aluminum powder slurry is all Evonik Hydrolan-214 and the curing agent is all Covestro Bayhydur 401-70. The remaining components are the same as in Example 1 and are not repeated.

[0169] The preparation method of the above waterborne metallic flash basecoat is the same as in Example 1 and is not repeated.

[0170] Table 1 Specific raw material components of the waterborne metallic flash basecoat of Examples 1-5

[0171]

[0172]

[0173]

[0174] Comparative Example 1

[0175] This comparative example provides a waterborne metallic flash basecoat similar to Example 1, except that the Evonik Bayhydol UH 2606 is replaced with the same amount of Covestro Bayhydrol A 2846 (i.e., the waterborne resin does not contain the waterborne polycarbonate-containing aliphatic anionic polyurethane dispersion having a glass transition temperature of 40-50°C). The remaining components are the same as in Example 1 and are not repeated.

[0176] Comparative Example 2

[0177] This comparative example provides a waterborne metallic flash basecoat similar to Example 1, except that the Evonik Bayhydrol UH 2952 / 1 is replaced with the same amount of Covestro Bayhydrol A 2846 (i.e., the waterborne resin does not contain the waterborne polycarbonate-containing aliphatic anionic polyurethane dispersion having a glass transition temperature of ≤5°C). The remaining components are the same as in Example 1 and are not repeated.

[0178] Comparative Example 3

[0179] This comparative example provides a waterborne metallic flash basecoat similar to Example 1, except that the Evonik Bayhydol UH 2606 and Bayhydrol UH 2952 / 1 are replaced with the same amount of Covestro Bayhydrol A 2846 (i.e., the waterborne resin only contains the waterborne self-crosslinking low-hydroxyl acrylate dispersion). The remaining components are the same as in Example 1 and are not repeated.

[0180] Comparative Example 4

[0181] This comparative example provides a water-based metallic flash basecoat similar to Example 1, except that Covestro Bayhydol UH 2606 and Bayhydrol A 2846 are replaced by the same amount of Covestro Bayhydrol UH 2952 / 1 (i.e. the water-based resin only contains a water-based polycarbonate-containing aliphatic anionic polyurethane dispersion with a glass transition temperature of ≤ 5°C). The other components are the same as in Example 1 and will not be repeated.

[0182] Comparative Example 5

[0183] This comparative example provides a water-based metallic flash basecoat similar to Example 1, except that Covestro Bayhydol UH 2606 and Bayhydrol A 2846 are replaced by the same amount of Covestro Bayhydrol UH 2952 / 1 (i.e. the water-based resin only contains a water-based polycarbonate-containing aliphatic anionic polyurethane dispersion with a glass transition temperature of ≤ 5°C). The other components are the same as in Example 1 and will not be repeated.

[0184] Comparative Example 6

[0185] This comparative example provides a water-based metallic flash basecoat similar to Example 1, except that the water-based resin (Covestro Bayhydol UH 2606, Bayhydrol UH 2952 / 1 and Bayhydrol A 2846) is replaced by Ruyi Uacryl 4219 (acrylic emulsion). The other components are the same as in Example 1 and will not be repeated.

[0186] Comparative Example 7

[0187] This comparative example provides a water-based metallic flash basecoat similar to Example 1, except that Covestro Bayhydol UH 2606 and Bayhydrol A 2846 are replaced by the same amount of Zhenxin 6803 (water-based acrylic resin emulsion). The other components are the same as in Example 1 and will not be repeated.

[0188] Comparative Example 8

[0189] This comparative example provides a water-based metallic flash basecoat similar to Example 1, except that 10 wt% of a dimethylethanolamine aqueous solution accounts for 1% of Component A. The other components are the same as in Example 1 and will not be repeated.

[0190] The preparation method of the above water-based metallic flash basecoat is similar to that of Example 1, except that in Step S1, the pH value of the system is not adjusted with 10 wt% of a dimethylethanolamine aqueous solution. The specific steps are as follows:

[0191] S1, each raw material was weighed according to the design ratio, the aluminum powder slurry was allowed to stand for 30 min, then the aqueous cellulose acetate butyrate solution, the gas chemical Surfynol 104BC and the defoaming agent were added into the aluminum powder slurry, and the mixture was uniformly mixed and allowed to stand for 2 h; the Cognis Bayhydol UH 2606, the wetting agent, the BYK AQUATIX 8421, the first part of water and the thickening agent were added into the system, and the mixture was uniformly mixed to obtain a first mixed system.

[0192] S2-S4, same as Example 1, and no longer described.

[0193] It was found that the aqueous metallic flash base paint of the present comparative example showed serious precipitation, flocculation, stratification and caking after 30 min, and had poor storage stability and could not be applied.

[0194] Application Examples 1, 3-4

[0195] Application Examples 1, 3-4 respectively provide a use method of an aqueous metallic flash base paint, which comprises the following steps:

[0196] The A component and the B component of Example 1, 3-4 were respectively mixed uniformly, and an activating diluent was added and uniformly mixed to obtain 3 groups of construction coatings with a solid content of 16%.

[0197] The activating diluent is composed of the following raw material components in mass percentage: aqueous cellulose acetate butyrate solution 20%, effect pigment orientation agent 4%, rheological aid 2% and water 74%. The aqueous cellulose acetate butyrate solution is composed of the following raw material components in mass percentage: aqueous cellulose acetate butyrate 20%, pH adjuster 0.3% and medium solution 79.7%. The rheological aid is composed of the following raw material components in mass percentage: organic modified synthetic layered silicate 2%, emulsifying dispersant 2% and water 96%.

[0198] It should be noted that the raw material components of the aqueous cellulose acetate butyrate solution and the rheological aid in the activating diluent are the same as those of the aqueous cellulose acetate butyrate solution and the rheological aid in the A component of Example 1, 3-4.

[0199] Application Examples 2, 5

[0200] Application Examples 2, 5 respectively provide a use method of an aqueous metallic flash base paint, which comprises the following steps:

[0201] The activating diluent was added into the A component of Example 2, 5 respectively, and the mixture was uniformly mixed to obtain 2 groups of construction coatings with a solid content of 15%.

[0202] The activated diluent is composed of the following raw material components in mass percentage: water-based cellulose acetate butyrate solution 15%, effect pigment orienting agent 3.5%, rheological aid 1.5%, and water 80%. The water-based cellulose acetate butyrate solution is composed of the following raw material components in mass percentage: water-based cellulose acetate butyrate 25%, pH regulator 0.5%, and medium solution 74.5%. The rheological aid is composed of the following raw material components in mass percentage: organic modified synthetic layered silicate 2.5%, emulsifying dispersant 2.5%, and water 95%.

[0203] It should be noted that the raw material components of the water-based cellulose acetate butyrate solution and the rheological aid in the activated diluent are the same as those of the water-based cellulose acetate butyrate solution and the rheological aid in the A component in Examples 2 and 5, respectively.

[0204] Application Examples 6-8

[0205] Application Examples 6-8 each provide a use method of a water-based metallic flash base paint, comprising the following steps:

[0206] The A component and the B component of each of Examples 6-8 are mixed uniformly, and the activated diluent is added and mixed uniformly, to obtain 3 groups of construction coatings with a solid content of 16% respectively.

[0207] The activated diluent is composed of the following raw material components in mass percentage: water-based cellulose acetate butyrate solution 25%, effect pigment orienting agent 4.5%, rheological aid 2.5%, and water 68%. The water-based cellulose acetate butyrate solution is composed of the following raw material components in mass percentage: water-based cellulose acetate butyrate 15%, pH regulator 0.1%, and medium solution 84.9%. The rheological aid is composed of the following raw material components in mass percentage: organic modified synthetic layered silicate 1.5%, emulsifying dispersant 1.5%, and water 97%.

[0208] It should be noted that the raw material components of the water-based cellulose acetate butyrate solution and the rheological aid in the activated diluent are the same as those of the water-based cellulose acetate butyrate solution and the rheological aid in the A component in Examples 6-8, respectively.

[0209] Application Comparative Examples 1-7

[0210] Application Comparative Examples 1-7 each provide a use method of a water-based metallic flash base paint, comprising the following steps:

[0211] The A component and the B component of each of Comparative Examples 1-7 are mixed uniformly, and the activated diluent is added and mixed uniformly, to obtain 7 groups of construction coatings with a solid content of 16% respectively. The activated diluent is the same as that in Application Example 1, and is not described again.

[0212] Application Comparative Example 8

[0213] The application comparative example provides a use method of a water-based metal flash base paint, including the following steps:

[0214] The A component and the B component of Example 1 are mixed uniformly, water is added, and mixing is performed uniformly to obtain a construction coating with a solid content of 16%.

[0215] Application Comparative Example 9

[0216] The application comparative example provides a use method of a water-based metal flash base paint, including the following steps:

[0217] The A component and the B component of Example 1 are mixed uniformly, water is added, and mixing is performed uniformly to obtain a construction coating with a solid content of 16%.

[0218] Application Comparative Example 10

[0219] The application comparative example provides a use method of a water-based metal flash base paint, which is similar to the application example 1, and the only difference is that the water-based cellulose acetate butyrate solution in the activating diluent is replaced by an equal amount of a rheological aid. That is, the activating diluent is composed of the following mass percentage of raw material components: effect pigment orientation agent 4%, rheological aid 22%, and water 74%. The remaining conditions are the same as those of the application example 1, and will not be repeated.

[0220] Performance test

[0221] The construction coatings provided by the application examples 1-8 and the application comparative examples 1-10 are subjected to performance tests.

[0222] (1) Tinplate panels are polished with 400-500 mesh sandpaper, ethanol is used to remove surface oil, and then the construction coatings provided by the application examples 1-8 and the application comparative examples 1-10 are coated, with a film thickness of 13-15 μm, and baked at 60°C for 2h. The color and appearance of the paint film of the obtained test panels, drying time, impact resistance, bending test, and cupping test are tested, and the test standards are shown in Table 2, and the test results are shown in Tables 3-4.

[0223] (2) The WB07-1 paint (purchased from Beijing Yulin Chemical Co., Ltd.) was coated on the cathodic electrodeposition paint (CED, model EcoTa8500, purchased from Shanghai Jinlitai Chemical Co., Ltd.) steel plate at a film thickness of 40-60 μm, and baked at 60°C for 2 h; then the construction coating provided by the application examples 1-8 and the application comparative examples 1-10 was coated, 2-3 coats were sprayed, each coat was flash dried for 5-10 min, and pre-baked at 60°C for 10 min (the film was dry to the touch), and then a two-component polyurethane clear paint (SB04-01, purchased from Beijing Yulin Chemical Co., Ltd.) was coated, the dry film thickness of the clear paint was 40-60 μm. The solvent resistance, water resistance, gasoline resistance, acid resistance, alkali resistance, and artificial climate accelerated aging resistance of the obtained test panels were tested, and the test standards are shown in Table 2, and the test results are shown in Tables 3-4.

[0224] Table 2 Test standards and requirements of the construction coating provided by the application examples and the application comparative examples

[0225]

[0226]

[0227] Table 3 Test results of the construction coating provided by the application examples

[0228]

[0229]

[0230]

[0231] In the table:

[0232] Thixotropic index: measured by using a NDJ-1 type rotary viscometer; the viscosity of the A component is adjusted by the amount of thickening agent (ISO 6 # ) to about 70 s, the low rotation (6 r / min) viscosity and the high rotation (60 r / min) viscosity are measured, and the calculation formula of the thixotropic index is: thixotropic index (DI) = low rotation viscosity / high rotation viscosity.

[0233] Appearance effect evaluation: 0 is "excellent", 1 is "qualified", and the larger the number greater than 1, the worse. 0-flat and smooth, delicate; 1-not delicate enough; 2-mild blooming; 3-coarse film, many pinholes; 4-obvious blooming, clouding of the film.

[0234] Workability: 0 is "excellent", 1 is "qualified", and the larger the number greater than 1, the worse. 0-no blooming, no sagging; 1-mild blooming; 2-mild sagging; 3-mild blooming and mild sagging; 4-poor flowability; 5-severe blooming and severe sagging.

[0235] Cross-hatch test: 0 is "excellent", 1 is "qualified", and the larger the number greater than 1, the worse. 0 - the substrate is not polished, and the adhesion is excellent; the rest is tested according to the cross-hatch test standard GB / T9286-1998 "Cross-hatch test of paint film of color paint and varnish".

[0236] Table 4 Performance test results of the construction coating provided by the application comparative example

[0237]

[0238]

[0239]

[0240] In summary, the water-based metal flash base color paint provided by the application selects a high glass transition temperature water-based polycarbonate aliphatic anionic polyurethane dispersion and a low glass transition temperature water-based aliphatic anionic polyurethane dispersion as the film-forming resin, and selectively adds a water-based self-crosslinking low-hydroxyl acrylate dispersion, through specific proportioning and the synergistic effect of each component, the characteristics of different types of water-based resins are brought to the best state, so that the finally obtained water-based metal flash base color paint has good gloss, thixotropy, and good directional arrangement of aluminum powder when sprayed in a large area, no blooming, good gunning, improved thixotropy, and balanced flexibility and hardness of the cured film, which can effectively solve the problem of "wet spraying wet" matching coating construction in the "water-based metal flash base color paint + topcoat varnish" system. The application obtains a water-based metal flash base color paint with excellent comprehensive performance through the synergistic effect of each raw material component and specific proportioning content, and has high practical value and popularization value.

[0241] The above only describes the preferred embodiments of the application and should not be used to limit the application, and any modifications, equivalent replacements or improvements made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. An aqueous metallic basecoat paint, characterized in that consists of the A component and the B component in a mass ratio of 100:(0-10); the A component comprises raw material components in the following mass percentages: 10-20% of an aqueous polycarbonate-containing aliphatic anionic polyurethane dispersion with a glass transition temperature of 40-50℃, 10-20% of an aqueous aliphatic anionic polyurethane dispersion with a glass transition temperature ≤5℃, 0-10% of an aqueous self-crosslinking low-hydroxyl acrylate dispersion, 12-18% of an aluminum paste, 2-4% of an aqueous cellulose acetate butyrate solution, 0.3-0.5% of a surfactant, 0.3-1% of an antifoaming agent, 5-10% of an effect pigment orienting agent, 1.5-5% of a pH adjusting agent, 0.5-1.5% of a wetting agent, 1-3% of a thickening agent, 5-8% of a first co-solvent, 18-22% of a rheological aid, and 10-30% of water; the B component comprises raw material components in the following mass percentages: 70-80% of a curing agent and 20-30% of a second co-solvent; the curing agent is at least one of hexamethylene diisocyanate or a hydrophilic aliphatic polyisocyanate.

2. The waterborne metallic flash basecoat paint according to claim 1, characterized in that the aqueous polycarbonate-containing aliphatic anionic polyurethane dispersion with a glass transition temperature of 40-50℃, the aqueous aliphatic anionic polyurethane dispersion with a glass transition temperature ≤5℃, and the aqueous self-crosslinking low-hydroxyl acrylate dispersion all have a solid content of 34-41%; the aqueous self-crosslinking low-hydroxyl acrylate dispersion has a hydroxyl content of 1-2%.

3. The waterborne metallic flash basecoat paint according to claim 1 or 2, characterized in that the aqueous polycarbonate-containing aliphatic anionic polyurethane dispersion with a glass transition temperature of 40-50℃ is Covestro Bayhydol UH 2606; the aqueous self-crosslinking low-hydroxyl acrylate dispersion is Covestro Bayhydrol A 2846; the aqueous aliphatic anionic polyurethane dispersion with a glass transition temperature ≤5℃ is at least one of Covestro Bayhydrol UH 2648 / 1, Covestro Bayhydrol UH 2110, Covestro Bayhydrol UH 2621, or Covestro Bayhydrol UH 2952 / 1.

4. The waterborne metallic flash basecoat paint according to claim 1, characterized in that the aluminum paste comprises, based on 100% of the A component, 6-8% of aluminum powder, 0.1-0.5% of a dispersant, and 6-10% of a medium solution; the aqueous cellulose acetate butyrate solution comprises, based on 100% of the A component, 0.4-0.6% of aqueous cellulose acetate butyrate, 0-0.01% of a pH adjusting agent, and 1.5-3.5% of a medium solution; the rheological aid comprises, based on 100% of the A component, 0.3-0.5% of an organic modified synthetic layered silicate, 0.3-0.5% of an emulsifying dispersant, and 17.5-21% of water.

5. The waterborne metallic flash basecoat paint according to claim 4, characterized in that the aluminum powder is at least one of Elastopoint Hydrolan-501, Elastopoint Hydrolan-2154, or Elastopoint Hydrolan-214; The medium solution is at least one of an aqueous ethylene glycol butyl ether solution, an aqueous propylene glycol methyl ether solution, an aqueous dipropylene glycol dimethyl ether solution, an aqueous N-methyl pyrrolidone solution, an aqueous dimethyl sulfoxide solution, an aqueous dimethyl formamide solution, an aqueous N-methyl formamide solution, and an aqueous tetrahydrofuran solution; the mass concentration of the medium solution is 50% to 75%; The pH regulator is an aqueous dimethyl ethanolamine solution of 8wt% to 12wt%.

6. The waterborne metallic flash basecoat paint according to claim 1, characterized in that The curing agent includes, based on 100% of the B component, 25% to 30% of low-viscosity hydrophobic hexamethylene diisocyanate, 25% to 30% of high-viscosity hydrophilic hexamethylene diisocyanate, and 18% to 22% of hydrophilic modified isophorone diisocyanate; wherein, The low-viscosity hydrophobic hexamethylene diisocyanate is at least one of Covestro Desmodur N3900, Covestro Desmodur N3600, or Wanhua WANNATE HT-600; The high-viscosity hydrophilic hexamethylene diisocyanate is at least one of Covestro Bayhydrol XP 2655, Covestro Bayhydur XP 2547, Covestro Bayhydur XP 2487 / 1, Covestro Bayhydur 304, or Covestro Bayhydur 305; The hydrophilic aliphatic polyisocyanate is at least one of Covestro Bayhydur 401-70 or Covestro Bayhydur 401-60.

7. The waterborne metallic flash base paint according to claim 1 or 6, wherein The first co-solvent is at least two of an aqueous dipropylene glycol methyl ether solution, an aqueous ethylene glycol butyl ether solution, an aqueous diethylene glycol monobutyl ether solution, or an aqueous propylene glycol methyl ether propylene carbonate solution; the mass concentration of the first co-solvent is 50% to 75%; The second co-solvent is at least one of propylene glycol methyl ether acetate, propylene glycol methyl ether propylene carbonate, propylene carbonate, propylene glycol diacetate, ethylene glycol butyl ether acetate, a divalent acid ester, and dipropylene glycol dimethyl ether; The surfactant is gas chemistry Surfynol 104BC; The effect pigment orienting agent is BYK AQUATIX 8421; The wetting agent is at least one of BYK-345, BYK-347, BYK-348, BYK-349, Tego-4100, or gas chemistry Surfynol 104BC; The thickening agent is at least one of Rheolite 299, RHEOBYK-H 7625VF, or RM-8W.

8. A process for the preparation of an aqueous metallic effect basecoat according to any one of claims 1 to 7, characterized in that The method includes the following steps: The method includes the following steps: S1, according to the design ratio, each raw material is weighed, the aluminum powder slurry is placed for 20-40 min, then the water-based cellulose acetate butyrate solution, the surfactant and the defoaming agent are added into the aluminum powder slurry, mixed uniformly, and placed for 1.5-2.5 h; the water-based polycarbonate aliphatic anionic polyurethane dispersion with a glass transition temperature of 40-50℃ is added into the system, mixed uniformly, the pH of the system is adjusted to 9-9.5 by using a pH adjuster; then the wetting agent, the effect pigment directional agent, the first part of water and the thickening agent are added, mixed uniformly, the pH of the system is adjusted to 8-8.5 by using a pH adjuster, and a first mixed system is obtained; S2, the water-based aliphatic anionic polyurethane dispersion with a glass transition temperature of ≤5℃ and the water-based self-crosslinking low-hydroxy acrylate dispersion are added into the second part of water, mixed uniformly, the pH of the system is adjusted to 8-8.5 by using a pH adjuster, and a second mixed system is obtained; S3, the second mixed system and the rheological aid are added into the first mixed system, mixed uniformly, and an A component is obtained; S4, the curing agent is added into the second auxiliary solvent, mixed uniformly, and a B component is obtained.

9. The application of the water-based metallic flash base paint according to any one of claims 1-7 or the water-based metallic flash base paint prepared by the preparation method of claim 8 in a vehicle coating.

10. Use of the aqueous metallic effect basecoat material according to claim 9 in automotive coatings, characterized in that The use method of the water-based metallic flash base paint comprises the following steps: The A component and the B component are mixed uniformly, the activating diluent is added, mixed uniformly, a coating with a solid content of 15%-17% is obtained, and the coating is uniformly coated on a metal substrate or a basecoat paint; The activating diluent comprises the following raw material components in mass percentage: water-based cellulose acetate butyrate solution 15%-25%, effect pigment directional agent 3.5%-4.5%, rheological aid 1.5%-2.5%, and water 68%-80%, and the sum of the components is 100%.

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