Visible light-induced transparent colored finish-coat paint and preparation method thereof

Abstract

The invention relates to a visible-light-induced transparent colored finish-coat paint and a preparation method thereof. The visible-light-induced transparent colored finish-coat paint is mainly prepared from the following components in parts by mass: # imgabs0, wherein a phosphomolybdate / hydroxyethyl cellulose hybrid solution is an ethylene glycol solution of phosphomolybdate hybrid modified hydroxyethyl cellulose. The defects that existing finishing varnish is colorless and transparent in a wet film state and a dry film state, and floating is easily caused by non-uniform construction during spray roller coating or batch scraping are overcome, a phosphomolybdate / hydroxyethyl cellulose hybrid solution is adopted as a color-changing substance, a reducing agent, a graphene modified silicone acrylic emulsion and a rheological additive are matched, and the color-changing finishing varnish is prepared. And by matching with other preferable component types and dosage proportions in the system, the coating has the advantages of roller coating or spray coating construction, facilitation of uniform coating, good durability and environmental protection.

Description

Technical Field

[0001] The invention relates to a visible light transparent colored finishing paint and a preparation method thereof, and is applied in the field of finishing paint production. Background Art

[0002] With the continuous improvement of people's quality of life and the continuous improvement of social construction, exterior wall imitation stone paint has stood out in the field of real estate facade decoration with its rich colors, convenient construction, water-based environmental protection, light weight and safety, and has become a mainstream product in the construction industry. At present, the coating system of exterior wall imitation stone paint is: base layer → putty layer → primer layer → intermediate coating layer → imitation stone paint layer → topcoat. The topcoat is the first line of defense for the facade of the building. Since it is always exposed to the environment, it mainly plays the role of waterproofing, dustproofing, anti-fouling, alkali resistance and anti-ultraviolet radiation to protect the wall and extend its service life. Therefore, the topcoat coating is an indispensable part of building and home decoration.

[0003] However, the mainstream topcoat varnishes on the market are mainly applied by spraying and roller coating. Since the topcoat varnish is colorless and transparent in both wet and dry film states, it often causes blooming problems due to uneven construction, including blooming due to roller marks caused by uneven roller coating (missed coating and over-coating, etc.), blooming due to local accumulation of spraying, and blooming due to repeated construction, etc., which directly affect the overall appearance and physical and chemical properties of the facade.

[0004] In the face of the limitations and performance contradictions of the above products, relevant researchers have carried out a series of improvement measures. For example, Chinese patent CN 116875136B discloses a scraping-type colorful special double-sided self-cleaning anti-scratch top varnish and its preparation method. By adopting the scraping construction method, it not only avoids the risk of missing coating and flowery, but also has a higher construction thickness and a fuller paint film effect. However, the product of this patent is still a colorless and transparent top varnish. The uniformity of the paint film thickness cannot be controlled during the scraping process, and knife marks will inevitably accumulate and flowery; in addition, the thick scraping construction will not only fill the pores of the imitation stone coating to the plane, affecting the concave and convex texture effect of the imitation stone, but also has a higher coating amount, and the cost and time required are also higher.

[0005] Therefore, it is urgent to provide a visible light transparent colored topcoat and a preparation method thereof which can be roller coated or sprayed, is colored in the wet film state and becomes transparent in the dry film state, is conducive to uniform coating, has good durability, and is green and environmentally friendly (the paint itself does not contain VOC, and no VOC is generated during the construction and film formation process). Summary of the invention

[0006] In order to overcome the shortcomings of existing topcoat varnishes that are colorless and transparent in both wet and dry film states, and are prone to floweriness due to uneven construction during spraying, roller coating or scraping, the present invention provides a visible light-transparent colored topcoat and a preparation method thereof, which uses a phosphomolybdate / hydroxyethyl cellulose hybrid solution as a color-changing substance, is matched with a reducing agent, a graphene-modified silicone acrylic emulsion and a rheological additive, and is matched with other preferred component types and dosage ratios in the system, and has the advantages of being able to be roller coated or sprayed, being colored in the wet film state and becoming transparent only in the dry film state, being conducive to uniform coating, having good durability, and being green and environmentally friendly (the paint itself does not contain VOC, and no VOC is generated during construction and film formation).

[0007] The technical solution of the present invention is as follows:

[0008] A visible light transparent colored topcoat is mainly prepared from the following components in the following mass proportions:

[0009]

[0010] The phosphomolybdate / hydroxyethyl cellulose hybrid solution is an ethylene glycol solution of phosphomolybdate hybrid modified hydroxyethyl cellulose, which is prepared by the following preparation method:

[0011] (1) mixing phosphomolybdate and ethylene glycol in a mass ratio of 15-25:300 to obtain a phosphomolybdate ethylene glycol solution, and mixing hydroxyethyl cellulose and ethylene glycol in a mass ratio of 5-15:100 to obtain a hydroxyethyl cellulose ethylene glycol solution;

[0012] (2) then dropping the phosphomolybdate ethylene glycol solution into the hydroxyethyl cellulose ethylene glycol solution at a volume ratio of 1:1-1.2 at 20-23° C., and continuously stirring for at least 2 h to obtain a phosphomolybdate / hydroxyethyl cellulose hybrid solution;

[0013] The graphene-modified silicone-acrylic emulsion is prepared by emulsion copolymerization reaction with silicone prepolymer and butyl acrylate as main raw materials and graphene as a modifier.

[0014] The visible light transparent colored topcoat of the present application adopts phosphomolybdate / hydroxyethyl cellulose hybrid solution as the color-changing substance, and is matched with a reducing agent, a graphene-modified silicone acrylic emulsion and a rheological additive, and is coordinated with other preferred component types and dosage ratios in the system. It has the advantages of being able to be roller coated or sprayed, being colored in the wet film state and becoming transparent in the dry film state, which is conducive to uniform coating, and being green and environmentally friendly (the paint itself is VOC-free, and no VOC is generated during the construction and film-forming process). Figure 1 The schematic diagram of the visible light transparent mechanism of the colored topcoat in this case is shown in FIG. Under the action of the reducing agent, the colored topcoat promotes the transfer of hydrogen electrons in the OH group of hydroxyethyl cellulose to Mo6+ It is reduced to Mo 5+ Under the action of visible light and oxygen, the interatomic charge migration occurs, causing strong absorption, that is, the visible light-induced transparency reaction process caused by the electron transfer mechanism between hydroxyethyl cellulose and phosphomolybdic acid. 5+ Oxidation to Mo 6+ , so that the topcoat on the coating changes from light blue translucent to colorless and transparent. The visible light-transparent colored topcoat in this case is in a light blue translucent state, and can be transparent due to visible light oxidation in visible light and natural air. The coating process of the paint film can be clearly observed during roller coating or spraying construction, which solves the problem of missing or over-coating caused by the colorless and transparent existing topcoat varnish, which affects the paint film effect and physical and chemical properties. It does not produce VOC during the construction process and the film-forming process, which is more friendly to construction personnel and the ecological environment. At the same time, the system of this case preferably uses graphene-modified silicone acrylic emulsion, which can give the colored topcoat the function of corrosion resistance and mildew resistance, and cooperates with the extended effects of waterproofing, mildew resistance and corrosion resistance of rheological additives, so that no other additives such as corrosion resistance and mildew resistance are needed in the formula system, and the durability of the coating is improved, achieving zero VOC in the system itself. The visible light-transparent colored topcoat fills the market gap and is of great significance to the development of new quality productivity in the coatings industry.

[0015] The reducing agent is a stannous chloride aqueous solution with a concentration of 18-22 g / L.

[0016] The preferred reducing agent stannous chloride has a strong reducing ability and can reduce most of the Mo6+ to Mo5+; secondly, it is easily soluble in water and ethylene glycol, has good compatibility in the topcoat formulation system, and will not destroy the stability of the topcoat; thirdly, its solution can adjust the stable state of the Mo valence state by the amount added, so that it can ensure that an irreversible visible light oxidation-induced transparent reaction can occur; fourthly, it is easy to store and transport, and has high safety, and can be applied to large-scale industrial production.

[0017] The rheological additive is a fluorine-silicon modified urea solution, which is prepared by the following preparation method:

[0018] The aqueous fluoroalkyl siloxane and the polyurea solution with a concentration of 110-120 g / ml are mixed in a mass ratio of 1:3.5-4.5, and placed in a constant temperature water bath of 58-62°C, stirred continuously for at least 3 hours, and then cooled to 20-23°C to obtain a fluorosilicone modified urea solution.

[0019] The preferred rheological additive fluorosilicone modified urea solution solves the industry pain point of easy precipitation of cellulose thickening, that is, it plays an anti-settling role. At the same time, it can also improve the surface smoothness of the coating, reduce the adhesion of the paint film surface, and has excellent stain resistance.

[0020] The phosphomolybdate is sodium phosphomolybdate or ammonium phosphomolybdate, or any combination of the two.

[0021] Sodium phosphomolybdate and ammonium phosphomolybdate have better water solubility and environmental friendliness than other phosphomolybdates, making them easier to dissolve and disperse in water-based coatings. The preparation process of sodium phosphomolybdate and ammonium phosphomolybdate is relatively mature, the procurement cost is relatively lower, and they are suitable for large-scale industrial applications.

[0022] The multifunctional defoamer is a polymer composite mineral oil type defoamer, the alkaline pH regulator is a multifunctional amine auxiliary agent, and the film-forming auxiliary agent is alcohol ester dodecahydrate.

[0023] The preferred multifunctional defoamer has both antifoaming and wetting effects. It simplifies the formulation design and production process, improves production efficiency, and reduces the cost of purchasing different additives and the cost of storage space.

[0024] The method for preparing the visible light transparent colored topcoat comprises the following steps performed in sequence:

[0025] (1) adding water to a stirrer, starting the stirrer, adjusting the speed to 300-500 rpm, adding the phosphomolybdate / hydroxyethyl cellulose hybrid solution, the multifunctional defoamer, and the alkaline pH regulator sequentially while stirring, then increasing the speed to 500-700 rpm, and mixing thoroughly until completely dissolved;

[0026] (2) maintaining the stirrer speed at 500-700 rpm, continuing to add the graphene-modified silicone acrylic emulsion and the film-forming aid, then increasing the speed to 800-1000 rpm, and continuing to disperse until the mixture is uniformly mixed to obtain a mixture;

[0027] (3) Maintaining the stirrer speed at 800-1000 rpm, slowly add the reducing agent and the rheological additive to the mixture so that the mixture obtained in step (2) gradually changes from a yellow translucent state to a blue translucent state, and continue to disperse for 8-10 minutes, and then cool to 20-23° C. to obtain a visible light transparent colored topcoat.

[0028] The preparation method of the visible light transparent colored topcoat has simple steps and is easy to operate.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] 1) The visible light transparent colored topcoat of the present application uses a phosphomolybdate / hydroxyethyl cellulose hybrid solution as a color-changing substance, and is matched with a reducing agent, a graphene-modified silicone acrylic emulsion and a rheological additive, and is matched with other preferred component types and dosage ratios in the system. It has the advantages of being able to be roller-coated or spray-coated, being colored in the wet film state and becoming transparent in the dry film state, which is conducive to uniform coating, and being green and environmentally friendly (the paint itself has no VOC, and no VOC is generated during the construction and film-forming process);

[0031] 2) After the preferred reducing agent is added, the system stability is better, so that the visible light transparent colored topcoat can be produced on a large scale in an industrial manner;

[0032] 3) The preferred rheological additive fluorine-silicon modified urea solution solves the industry pain point problem of easy precipitation of cellulose thickening, that is, it plays an anti-settling role, and at the same time can improve the surface smoothness of the coating, reduce the adhesion of the paint film surface, and has excellent stain resistance;

[0033] 4) The preparation method of the visible light transparent colored topcoat has simple steps and is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the visible light-induced transparency mechanism of the visible light-induced transparent colored topcoat and the preparation method thereof of the present invention;

[0035] Figure 2 This is a comparison diagram of visible light-transparent colored topcoat and preparation method thereof of Example 2 of the present invention, showing visible light-transparent sample effects at different oxygen concentrations;

[0036] Figure 3 The Mo3d atomic level XPS spectrum of the visible light transparent colored topcoat and the preparation method thereof of the present invention (wherein (A) is Figure 2 (A) XPS spectrum of the topcoat; (B) Figure 2 (B) XPS spectrum of the top coating). DETAILED DESCRIPTION

[0037] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments.

[0038] Example 1

[0039] The visible light transparent colored topcoat of the present invention is mainly prepared from the following components in the following mass proportions:

[0040]

[0041] The phosphomolybdate / hydroxyethyl cellulose hybrid solution is an ethylene glycol solution of phosphomolybdate hybrid modified hydroxyethyl cellulose, which is prepared by the following preparation method:

[0042] (1) mixing phosphomolybdate and ethylene glycol in a mass ratio of 20:300 to obtain a phosphomolybdate ethylene glycol solution, and mixing hydroxyethyl cellulose and ethylene glycol in a mass ratio of 10:100 to obtain a hydroxyethyl cellulose ethylene glycol solution;

[0043] (2) then, at 21° C., the phosphomolybdate ethylene glycol solution was dropped into the hydroxyethyl cellulose ethylene glycol solution at a volume ratio of 1:1, and stirred for 2 h to obtain a phosphomolybdate / hydroxyethyl cellulose hybrid solution;

[0044] The graphene-modified silicone-acrylic emulsion is prepared by emulsion copolymerization reaction with silicone prepolymer and butyl acrylate as main raw materials and graphene as a modifier.

[0045] The reducing agent is a stannous chloride aqueous solution with a concentration of 20 g / L.

[0046] The rheological additive is a fluorine-silicon modified urea solution, which is prepared by the following preparation method:

[0047] Aqueous fluoroalkylsiloxane and polyurea solution with a concentration of 100 g / ml were mixed in a mass ratio of 1:4, placed in a 60° C. constant temperature water bath, stirred for 3 h, and then cooled to 21° C. to obtain a fluorosilicone-modified urea solution.

[0048] The phosphomolybdate is sodium phosphomolybdate.

[0049] The multifunctional defoamer is a polymer composite mineral oil type defoamer, the alkaline pH regulator is a multifunctional amine auxiliary agent, and the film-forming auxiliary agent is alcohol ester dodecahydrate.

[0050] The method for preparing the visible light transparent colored topcoat is characterized by comprising the following steps performed in sequence:

[0051] (1) adding water to a stirrer, starting the stirrer, adjusting the speed to 300 rpm, adding the phosphomolybdate / hydroxyethyl cellulose hybrid solution, the multifunctional defoamer, and the alkaline pH regulator sequentially while stirring, then increasing the speed to 500 rpm, and mixing thoroughly until they are completely dissolved;

[0052] (2) maintaining the stirrer speed at 500 rpm, continuing to add the graphene-modified silicone-acrylic emulsion and the film-forming aid, then increasing the speed to 800 rpm, and continuing to disperse until the mixture is uniformly mixed to obtain a mixture;

[0053] (3) Maintaining the stirrer speed at 800 rpm, slowly add the reducing agent and the rheological additive to the mixture, so that the mixture obtained in step (2) gradually changes from a yellow translucent state to a blue translucent state, and continue to disperse for 8 minutes, and then cool to 21° C. to obtain a visible light transparent colored topcoat.

[0054] Example 2

[0055] The visible light transparent colored topcoat of the present invention is mainly prepared from the following components in the following mass proportions:

[0056]

[0057] The phosphomolybdate / hydroxyethyl cellulose hybrid solution is an ethylene glycol solution of phosphomolybdate hybrid modified hydroxyethyl cellulose, which is prepared by the following preparation method:

[0058] (1) mixing phosphomolybdate and ethylene glycol in a mass ratio of 15:300 to obtain a phosphomolybdate ethylene glycol solution, and mixing hydroxyethyl cellulose and ethylene glycol in a mass ratio of 15:100 to obtain a hydroxyethyl cellulose ethylene glycol solution;

[0059] (2) then, at 20° C., the phosphomolybdate ethylene glycol solution was dropped into the hydroxyethyl cellulose ethylene glycol solution at a volume ratio of 1:1.1, and stirred for 2.5 h to obtain a phosphomolybdate / hydroxyethyl cellulose hybrid solution;

[0060] The graphene-modified silicone-acrylic emulsion is prepared by emulsion copolymerization reaction with silicone prepolymer and butyl acrylate as main raw materials and graphene as a modifier.

[0061] The reducing agent is a stannous chloride aqueous solution with a concentration of 18 g / L.

[0062] The rheological additive is a fluorine-silicon modified urea solution, which is prepared by the following preparation method:

[0063] The aqueous fluoroalkylsiloxane and the polyurea solution with a concentration of 110 g / ml were mixed in a mass ratio of 1:4.5, placed in a 58° C. constant temperature water bath, stirred continuously for 3.5 h, and then cooled to 23° C. to obtain a fluorosilicone-modified urea solution.

[0064] The phosphomolybdate is ammonium phosphomolybdate.

[0065] The multifunctional defoamer is a polymer composite mineral oil type defoamer, the alkaline pH regulator is a multifunctional amine auxiliary agent, and the film-forming auxiliary agent is alcohol ester dodecahydrate.

[0066] The method for preparing the visible light transparent colored topcoat comprises the following steps performed in sequence:

[0067] (1) adding water to a stirrer, starting the stirrer, adjusting the speed to 400 rpm, adding the phosphomolybdate / hydroxyethyl cellulose hybrid solution, the multifunctional defoamer, and the alkaline pH regulator sequentially while stirring, then increasing the speed to 600 rpm, and mixing thoroughly until completely dissolved;

[0068] (2) maintaining the stirrer speed at 600 rpm, continuing to add the graphene-modified silicone-acrylic emulsion and the film-forming aid, then increasing the speed to 900 rpm, and continuing to disperse until the mixture is uniformly mixed to obtain a mixture;

[0069] (3) Maintaining the stirrer speed at 700 rpm, slowly add the reducing agent and the rheological additive to the mixture, so that the mixture obtained in step (2) gradually changes from a yellow translucent state to a blue translucent state, and continue to disperse for 9 minutes, and then cool to 20° C. to obtain a visible light transparent colored topcoat.

[0070] Example 3

[0071] The visible light transparent colored topcoat of the present invention is mainly prepared from the following components in the following mass proportions:

[0072]

[0073] The phosphomolybdate / hydroxyethyl cellulose hybrid solution is an ethylene glycol solution of phosphomolybdate hybrid modified hydroxyethyl cellulose, which is prepared by the following preparation method:

[0074] (1) mixing phosphomolybdate and ethylene glycol in a mass ratio of 25:300 to obtain a phosphomolybdate ethylene glycol solution, and mixing hydroxyethyl cellulose and ethylene glycol in a mass ratio of 5:100 to obtain a hydroxyethyl cellulose ethylene glycol solution;

[0075] (2) then, at 23° C., the phosphomolybdate ethylene glycol solution was dropped into the hydroxyethyl cellulose ethylene glycol solution at a volume ratio of 1:1.2, and stirred for 3 h to obtain a phosphomolybdate / hydroxyethyl cellulose hybrid solution;

[0076] The graphene-modified silicone-acrylic emulsion is prepared by emulsion copolymerization reaction with silicone prepolymer and butyl acrylate as main raw materials and graphene as a modifier.

[0077] The reducing agent is a stannous chloride aqueous solution with a concentration of 22 g / L.

[0078] The rheological additive is a fluorine-silicon modified urea solution, which is prepared by the following preparation method:

[0079] The aqueous fluoroalkyl siloxane and the polyurea solution with a concentration of 120 g / ml were mixed in a mass ratio of 1:3.5, placed in a constant temperature water bath at 62° C., stirred for 4 hours, and then cooled to 20° C. to obtain a fluorosilicone-modified urea solution.

[0080] The phosphomolybdate is a combination of sodium phosphomolybdate and ammonium phosphomolybdate.

[0081] The multifunctional defoamer is a polymer composite mineral oil type defoamer, the alkaline pH regulator is a multifunctional amine auxiliary agent, and the film-forming auxiliary agent is alcohol ester dodecahydrate.

[0082] The method for preparing the visible light transparent colored topcoat comprises the following steps performed in sequence:

[0083] (1) adding water to a stirrer, starting the stirrer, adjusting the speed to 500 rpm, adding the phosphomolybdate / hydroxyethyl cellulose hybrid solution, the multifunctional defoamer, and the alkaline pH regulator sequentially while stirring, then increasing the speed to 500-700 rpm, and mixing thoroughly until completely dissolved;

[0084] (2) maintaining the stirrer speed at 700 rpm, continuing to add the graphene-modified silicone-acrylic emulsion and the film-forming aid, then increasing the speed to 1000 rpm, and continuing to disperse until the mixture is uniformly mixed to obtain a mixture;

[0085] (3) Maintaining the stirrer speed at 1000 rpm, slowly add the reducing agent and the rheological additive to the mixture, so that the mixture obtained in step (2) gradually changes from a yellow translucent state to a blue translucent state, and continue to disperse for 10 minutes, and then cool to 23° C. to obtain a visible light transparent colored topcoat.

[0086] Raw material information involved in each embodiment

[0087] Graphene modified silicone acrylic emulsion: SD-5281, Jiangsu Shengda New Material Technology Co., Ltd.;

[0088] Multifunctional defoamer: ST 2410, BASF AG;

[0089] Alkaline pH adjuster: AMP-95, Dow Chemical Company;

[0090] Phosphomolybdate: PMoA, China National Pharmaceutical Group

[0091] Hydroxyethyl cellulose: EBS481 FQ, Akzo Nobel

[0092] Ethylene glycol: Xiamen Xinlianfa Import and Export Co., Ltd.

[0093] Film-forming aids: 290Plus, The Dow Chemical Company;

[0094] Reducing agent: CAS 7772-99-8, Nanjing Chemical Reagent;

[0095] Polyurea solution: BYK420, BYK Chemical;

[0096] Water-based fluoroalkyl siloxane: SF-334, Guangdong Biaomei Fluorosilicone New Materials Co., Ltd.

[0097] Experimental data:

[0098] Comparative Example 1: The difference between this comparative example and Example 2 is that no reducing agent is added;

[0099] Comparative Example 2: The difference between this comparative example and Example 2 is that ordinary silicone acrylic emulsion is used to replace the graphene-modified silicone acrylic emulsion in Example 2;

[0100] Comparative Example 3: The difference between this comparative example and Example 2 is that no rheological additive is added.

[0101] The obtained embodiments and comparative examples of the present invention were analyzed and tested accordingly:

[0102] Testing method: The performance test indicators of the paints are implemented in accordance with the standard HG / T 5065-2016 "Top Varnish for Architectural Coatings". The EscaLab 250Xi X-ray photoelectron spectrometer produced by Thermo Fisher Scientific is used to analyze the element type, element chemical valence state and element relative content of each paint coating. The self-made coating visible light oxidation in-situ film-forming test device is used to test and analyze the color change of each paint under different oxygen concentrations.

[0103] The results are as follows:

[0104] one, Figure 2 The following is a comparison of the visible light-induced transparent sample effects of the colored topcoat of Example 2 under different oxygen concentrations, wherein the oxygen concentration conditions from left to right are: (A) 0% O2 + 100% N2; (B) 20% O2 + 80% N2; (C) 50% O2 + 50% N2). Figure 2 It can be seen intuitively that in an oxygen-free environment, the colored topcoat does not fade; when the oxygen concentration reaches 20% or above, the colored topcoat can completely undergo visible light oxidation to become transparent, indicating that the oxygen concentration in the natural environment is sufficient to cause the colored topcoat to fade to a transparent state.

[0105] 2. Mo3d atomic energy level and Mo 5+ / Mo value analysis

[0106] Figure 3 The Mo3d atomic level XPS spectrum of the colored topcoat coating of Example 2, wherein (A) is Figure 2 (A) XPS spectrum of the topcoat; (B) Figure 2 (B) XPS spectrum of the topcoat. Table 1 shows the binding energy of Mo3d and Mo 5+ / Mo value test table.

[0107] Table 1 Binding energy of Mo3d and Mo in the coating before and after visible light-induced transparency 5+ / Mo value

[0108]

[0109] Combination Figure 3 As shown in Table 1, Mo in the visible light oxygen-free environment 5+ The 3d characteristic peaks of Mo are 231.66eV and 234.87eV. 6+ The 3d characteristic peaks are 232.86eV and 236.03eV; in the visible light oxygen environment, Mo 5+ The 3d characteristic peaks of Mo are 231.83eV and 235.53eV. 6+ The 3d characteristic peaks of the Mo atom are 233.06eV and 236.20eV. It can be seen that the binding energy of their 3d characteristic peaks has changed in the oxygen-free and oxygen-containing environments of visible light, and the chemical environment of the Mo atom has changed. After integration, the area occupied by each peak is calculated, and finally the Mo 5+ / Mo ratio. Mo is dried under visible light and oxygen environment 5+ The proportion decreases in Mo, so Mo 6+ The proportion of Mo in the coating increases, which shows that phosphomolybdate / hydroxyethyl cellulose produces Mo in the topcoat film. 5+ to Mo 6+ Visible light-induced transparent oxidation reaction.

[0110] 3. Coating performance testing

[0111] Table 2 Test results of coating properties

[0112]

[0113] As can be seen from Table 2, the visible light transparent colored topcoats prepared in Examples 1-3 all meet the various standard requirements of HG / T 5065-2016 "Top varnish for architectural coatings". The topcoat prepared in Comparative Example 1 can also meet the above standard requirements, indicating that the addition of the reducing agent has no significant effect on the performance of the topcoat. However, the topcoat prepared in Comparative Example 2 has the problem of artificial aging bubbles and cracking, indicating that the graphene-modified silicone acrylic emulsion can make up for the defect that special additives can shorten the service life in the topcoat formula, thereby giving the coating excellent durability. The topcoat prepared in Comparative Example 3 has the problem of precipitation and stratification, indicating that the fluorosilicone-modified urea solution plays an anti-settling role as a rheological additive in this formulation system.

[0114] 4. Detection of coating discoloration under different oxygen concentrations

[0115] Table 3 Coating discoloration under different oxygen concentrations

[0116] <![CDATA[O2 concentration]]> 0％ 5％ 15％ 20％ 30％ 50％ Example 2 × × √ √ √ √ Comparison 1 × × × × × × Comparison 2 × × × √ √ √

[0117] ×: no change in color; √: variable transparency

[0118] As can be seen from Table 3, the visible light-transparent colored topcoat prepared in the present application itself is light blue and translucent. When the oxygen concentration is 15%, the topcoat changes from light blue to transparent, while the comparative example 1 (without adding a reducing agent) does not change color when the oxygen concentration is as high as 50%, indicating that after the reducing agent is added, sufficient Mo5+ in the topcoat is guaranteed to present a light blue and translucent metastable state, and under the action of visible light, oxygen reoxidizes the Mo5+ in the topcoat to Mo6+, thereby fading to a transparent stable state.

[0119] 5. In summary, the visible light-transparent colored topcoat in this case has the advantages of being able to be applied by roller or spray, being colored in the wet film state and becoming transparent in the dry film state, which is conducive to uniform coating, good durability, and being green and environmentally friendly (the paint itself does not contain VOC, and no VOC is generated during the construction and film-forming process).

Claims

1. A visible light transparent colored finish paint, characterized in that: It is mainly prepared by the following components in the following mass ratio: The phosphomolybdate / hydroxyethyl cellulose hybrid solution is an ethylene glycol solution of phosphomolybdate hybrid modified hydroxyethyl cellulose, which is prepared by the following preparation method: (1) mixing phosphomolybdate and ethylene glycol in a mass ratio of 15-25:300 to obtain a phosphomolybdate ethylene glycol solution, and mixing hydroxyethyl cellulose and ethylene glycol in a mass ratio of 5-15:100 to obtain a hydroxyethyl cellulose ethylene glycol solution; (2) then dropping the phosphomolybdate ethylene glycol solution into the hydroxyethyl cellulose ethylene glycol solution at a volume ratio of 1:1-1.2 at 20-23° C., and continuously stirring for at least 2 h to obtain a phosphomolybdate / hydroxyethyl cellulose hybrid solution; The graphene-modified silicone-acrylic emulsion is prepared by emulsion copolymerization reaction with silicone prepolymer and butyl acrylate as main raw materials and graphene as a modifier.

2. The visible light transparent colored finish paint according to claim 1, characterized in that: The reducing agent is a stannous chloride aqueous solution with a concentration of 18-22 g / L.

3. The visible light transparent colored finish paint according to claim 1, characterized in that: The rheological additive is a fluorine-silicon modified urea solution, which is prepared by the following preparation method: The aqueous fluoroalkyl siloxane and the polyurea solution with a concentration of 110-120 g / ml are mixed in a mass ratio of 1:3.5-4.5, and placed in a constant temperature water bath of 58-62°C, stirred continuously for at least 3 hours, and then cooled to 20-23°C to obtain a fluorosilicone modified urea solution.

4. The visible light transparent colored finish paint according to claim 1, characterized in that: The phosphomolybdate is sodium phosphomolybdate or ammonium phosphomolybdate, or any combination of the two.

5. The visible light transparent colored finish paint according to claim 1, characterized in that: The multifunctional defoamer is a polymer composite mineral oil type defoamer, the alkaline pH regulator is a multifunctional amine auxiliary agent, and the film-forming auxiliary agent is alcohol ester dodecahydrate.

6. The method for preparing a visible light transparent colored topcoat according to any one of claims 1 to 5, characterized in that: The steps are as follows: (1) adding water to a stirrer, starting the stirrer, adjusting the speed to 300-500 rpm, adding the phosphomolybdate / hydroxyethyl cellulose hybrid solution, the multifunctional defoamer, and the alkaline pH regulator sequentially while stirring, then increasing the speed to 500-700 rpm, and mixing thoroughly until completely dissolved; (2) maintaining the stirrer speed at 500-700 rpm, continuing to add the graphene-modified silicone acrylic emulsion and the film-forming aid, then increasing the speed to 800-1000 rpm, and continuing to disperse until the mixture is uniformly mixed to obtain a mixture; (3) Maintaining the stirrer speed at 800-1000 rpm, slowly add the reducing agent and the rheological additive to the mixture so that the mixture obtained in step (2) gradually changes from a yellow translucent state to a blue translucent state, and continue to disperse for 8-10 minutes, and then cool to 20-23° C. to obtain a visible light transparent colored topcoat.

Images