A weather-resistant and easy-to-clean fluorosilicone modified acrylic anti-graffiti coating and preparation method thereof

Abstract

The present invention belongs to the technical field of coatings and polymer materials, and discloses a weather-resistant and easy-to-clean fluorosilicone modified acrylic anti-graffiti coating and a preparation method thereof. The preparation method comprises: subjecting hydrogen-containing silicone oil, allyl polyoxyethylene ether and perfluoroalkylethylene to a silylation reaction under anhydrous solvent and catalyst conditions to obtain a polyether-modified fluorosilicone oil; subjecting the polyether-modified fluorosilicone oil to a mixed reaction with (meth) acryloyloxyethyl isocyanate and an organic tin catalyst to obtain a polyether-modified fluorosilicone oil containing a double bond; and then subjecting the polyether-modified fluorosilicone oil to an emulsion copolymerization reaction with an acrylic monomer and an acrylate monomer to obtain a weather-resistant and easy-to-clean fluorosilicone modified acrylic anti-graffiti coating. The preparation method of the present invention has a simple process and is easy to control. The hydrophobic and oleophobic easy-to-clean effect of the coating is significantly improved by introducing a fluorine-containing segment and a polysiloxane segment, and the adhesion, strength and weather resistance of the coating are significantly improved by a reasonable cross-linking structure design.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings and polymer materials, and in particular relates to a weather-resistant and easy-to-clean fluorosilicone-modified acrylic anti-graffiti coating and a preparation method thereof. Background Art

[0002] Anti-graffiti paint is a paint with special surface functions. Its surface has low surface tension and is both hydrophobic and oleophobic. Water-based or oily handwriting can be easily removed by wiping or washing, and dirt rolls off naturally. It has self-cleaning properties, and self-adhesive paper will easily fall off after being pasted, effectively preventing "urban psoriasis".

[0003] Anti-graffiti coatings are divided into two categories according to the solvent system: solvent-based and water-based. Solvent-based anti-graffiti coatings have the advantages of good water resistance and high film strength, but slightly poor oleophobic performance. At the same time, a large amount of organic solvents leads to high costs and poor environmental protection. Water-based anti-graffiti coatings are mainly fluorine-modified or silicone-modified acrylate or polyurethane emulsions. They have the low surface tension characteristics of fluorine compounds or silicone compounds and the high adhesion characteristics of acrylates or polyurethanes, and have therefore been widely studied.

[0004] Patent CN 109054571 A discloses a fluorinated silicone modified anti-graffiti coating, which is obtained by grafting acrylic monomers and PMTFPS fluorinated silicone polymers after chain extension and toughening modification with epoxy resin, and then crosslinking and curing with blocked aliphatic isocyanate. However, PMTFPS fluorinated silicone polymer undergoes polymerization and crosslinking reaction with isocyanate through the hydroxyl groups at both ends. The fluorinated polysiloxane chain segments are located inside the crosslinked network, while the epoxy resin and polyacrylic acid are located outside the crosslinked network, resulting in the low surface tension performance and weather resistance of the fluorinated polysiloxane not being well utilized.

[0005] Patent CN 111607092 A discloses a method for preparing an epoxy silicone oil-modified acrylate anti-graffiti emulsion, in which acrylamide is added during emulsion polymerization to introduce an amide group into the emulsion molecular chain, and then reacts with terminal epoxy silicone oil. The silicone oil is connected through the ring-opening reaction of the amide group and the epoxy group, which greatly improves the water resistance, softness, and anti-fouling properties of the emulsion. The polysiloxane segment of the emulsion polymer is located on the polyacrylate side chain, which can better exert the low surface tension performance of polysiloxane, but the polysiloxane segment and the acrylate segment are only connected by the epoxy groups at both ends, and the polymerization strength is low, resulting in slightly poor film strength and weather resistance. Summary of the invention

[0006] In view of the shortcomings and deficiencies of the above prior art, the primary purpose of the present invention is to provide a method for preparing a weather-resistant and easy-to-clean fluorosilicone modified acrylic anti-graffiti coating.

[0007] Another object of the present invention is to provide a weather-resistant and easy-to-clean fluorosilicone-modified acrylic anti-graffiti coating prepared by the above method.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A method for preparing a weather-resistant and easy-to-clean fluorosilicone-modified acrylic anti-graffiti coating comprises the following preparation steps:

[0010] (1) adding hydrogen-containing silicone oil, allyl polyoxyethylene ether (APEG) and perfluoroalkylethylene into an anhydrous solvent and mixing and dissolving them uniformly, then adding chloroplatinic acid catalyst and heating and stirring to react, and after the reaction is completed, removing the solvent in vacuo to obtain polyether-modified fluorinated silicone oil;

[0011] (2) mixing the polyether-modified fluorinated silicone oil with (meth)acryloyloxyethyl isocyanate and an organic tin catalyst, heating and stirring to react, and obtaining a polyether-modified fluorinated silicone oil containing a double bond;

[0012] (3) adding a polyether-modified fluorinated silicone oil containing a double bond, an acrylic monomer, an acrylate monomer and an emulsifier into water, stirring and emulsifying the mixture uniformly, heating the mixture to 60 to 90° C. under nitrogen protection, adding an initiator solution dropwise for copolymerization, and obtaining a weather-resistant and easy-to-clean fluorinated silicone-modified acrylic anti-graffiti coating.

[0013] The preparation reaction formula of the above-mentioned polyether-modified fluorinated silicone oil containing double bonds is exemplified as follows:

[0014]

[0015] Preferably, the hydrogen-containing silicone oil has an active hydrogen content of 0.2 to 1.5 wt % and a number average molecular weight of 2000 to 10000 g / mol.

[0016] Preferably, the number average molecular weight of the allyl polyoxyethylene ether is 500 to 1500 g / mol.

[0017] Preferably, the perfluoroalkylethylene is a perfluoroalkylethylene having 6 to 10 carbon atoms.

[0018] Preferably, the molar ratio of the active hydrogen content of the hydrogen-containing silicone oil to the addition of allyl polyoxyethylene ether and perfluoroalkyl ethylene is 1:0.2-0.6:0.3-0.7. Too high a ratio of allyl polyoxyethylene ether and too low a ratio of perfluoroalkyl ethylene will result in reduced hydrophobic and oleophobic properties of the coating. Too low a ratio of allyl polyoxyethylene ether and too high a ratio of perfluoroalkyl ethylene will result in poor emulsification of the polyether-modified fluorinated silicone oil containing double bonds, reduce the copolymerization effect with acrylic monomers, and reduce the cross-linking strength, and the adhesion, strength and weather resistance of the coating will be significantly reduced.

[0019] Preferably, the anhydrous solvent is toluene.

[0020] Preferably, the temperature of the heating and stirring reaction in step (1) is 80-90° C., and the time is 4-8 h; the temperature of the heating and stirring reaction in step (2) is 30-70° C., and the time is 2-8 h.

[0021] Preferably, the molar ratio of the added amount of the (meth)acryloyloxyethyl isocyanate to the allyl polyoxyethylene ether is 0.8-1.2:1.

[0022] Preferably, the acrylic acid monomer is (meth)acrylic acid; the acrylic acid ester monomer is methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isooctyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate.

[0023] Preferably, the mass ratio of the polyether-modified fluorinated silicone oil containing double bonds to the acrylic acid monomer and the acrylic ester monomer is 15-30:100:30-60.

[0024] Preferably, the emulsifier is alkylphenol polyoxyethylene ether, alkyl alcohol polyoxyethylene ether sulfate, allyloxy alkylphenol polyoxyethylene ether, sodium alkyl sulfate, alkyl benzene sulfonate.

[0025] Preferably, the initiator is ammonium persulfate or potassium persulfate.

[0026] Preferably, the copolymerization reaction temperature is 60-80° C. and the time is 2-8 hours.

[0027] A weather-resistant and easy-to-clean fluorosilicone modified acrylic anti-graffiti paint is prepared by the method.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The preparation method of the present invention simultaneously grafts a hydrophilic polyether chain and a hydrophobic and oleophobic perfluoroalkyl chain on the polysiloxane side chain through a hydrosilylation reaction, and then uses (meth)acryloyloxyethyl isocyanate to end-cap the polyether hydroxyl group, grafts a double bond with copolymerization activity, and obtains a polyether-modified fluorinated silicone oil containing a double bond. Due to the introduction of the hydrophilic polyether chain, the emulsification of the obtained polyether-modified fluorinated silicone oil containing a double bond is improved, and the cross-linking copolymerization effect with acrylic acid monomers and acrylate monomers is improved. At the same time, because the double bonds with cross-linking copolymerization activity are all located in the hydrophilic polyether chain, after copolymerization and cross-linking with acrylic acid monomers and acrylate monomers, the hydrophilic polyether chain segment is cross-linked, entangled and embedded, thereby reducing the hydrophilicity of the polymer coating. In addition, due to the strong hydrophobic properties of the polysiloxane chain and the perfluoroalkyl chain, the reverse aggregation to the hydrophilic polyether chain (cross-linking center) during the copolymerization reaction greatly reduces the entanglement and embedding of the polysiloxane chain and the perfluoroalkyl chain, and significantly improves the hydrophobic and oleophobic effect of the polymer coating. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0031] Example 1

[0032] A method for preparing a weather-resistant and easy-to-clean fluorosilicone-modified acrylic anti-graffiti coating comprises the following preparation steps:

[0033] (1) Adding hydrogenated silicone oil with an active hydrogen content of 0.75 wt % and a number average molecular weight of 6000 g / mol, APEG-500, perfluorobutylethylene and toluene solvent into a reaction kettle, mixing and dissolving them uniformly, wherein the molar ratio of the active hydrogen content of the hydrogenated silicone oil to the added APEG-500 and perfluorobutylethylene is 1:0.4:0.5, adding chloroplatinic acid catalyst after nitrogen substitution, heating to 80° C. and stirring for 6 h, and removing the solvent and unreacted raw materials in vacuo after the reaction is completed to obtain a polyether-modified fluorinated silicone oil.

[0034] (2) Mixing the polyether-modified fluorinated silicone oil with methacryloyloxyethyl isocyanate and dibutyltin dilaurate catalyst, wherein the molar ratio of methacryloyloxyethyl isocyanate to APEG-500 is 1:1, heating to 50° C. and stirring for 6 h to obtain a polyether-modified fluorinated silicone oil containing a double bond.

[0035] (3) Add the double-bond polyether-modified fluorinated silicone oil, acrylic acid, butyl methacrylate, hydroxyethyl methacrylate monomers in a mass ratio of 15:100:30:20, nonylphenol polyoxyethylene ether (the concentration in the reaction solution is 3 wt %) and sodium dodecylbenzene sulfonate (1 wt %) into water, stir and emulsify evenly, heat to 75° C. under nitrogen protection, add ammonium persulfate solution dropwise and carry out copolymerization reaction for 5 h to obtain a weather-resistant and easy-to-clean fluorinated silicone modified acrylic anti-graffiti coating with a solid content of 66%.

[0036] Example 2

[0037] A method for preparing a weather-resistant and easy-to-clean fluorosilicone-modified acrylic anti-graffiti coating comprises the following preparation steps:

[0038] (1) Hydrogenated silicone oil with an active hydrogen content of 0.75 wt % and a number average molecular weight of 6000 g / mol, APEG-1000, perfluorohexylethylene and toluene solvent are added to a reaction kettle and mixed and dissolved uniformly, wherein the molar ratio of the active hydrogen content of the hydrogenated silicone oil to the added APEG-1000 and perfluorohexylethylene is 1:0.3:0.6. After nitrogen substitution, chloroplatinic acid catalyst is added, and the mixture is heated to 85° C. and stirred for 6 h. After the reaction is completed, the solvent and unreacted raw materials are removed in vacuo to obtain a polyether-modified fluorinated silicone oil.

[0039] (2) The polyether-modified fluorinated silicone oil was mixed with acryloyloxyethyl isocyanate and dibutyltin dilaurate catalyst, with the molar ratio of acryloyloxyethyl isocyanate to APEG-1000 being 1:1, and the mixture was heated to 60° C. and stirred for reaction for 6 h to obtain a polyether-modified fluorinated silicone oil containing double bonds.

[0040] (3) Add the double-bond polyether-modified fluorinated silicone oil, acrylic acid, methyl methacrylate, isooctyl methacrylate monomers in a mass ratio of 20:100:20:20, nonylphenol polyoxyethylene ether (the concentration in the reaction solution is 3 wt %) and sodium dodecylbenzene sulfonate (1 wt %) into water, stir and emulsify evenly, heat to 75° C. under nitrogen protection, add ammonium persulfate solution dropwise and carry out copolymerization reaction for 5 h to obtain a weather-resistant and easy-to-clean fluorinated silicone modified acrylic anti-graffiti coating with a solid content of 65%.

[0041] Example 3

[0042] A method for preparing a weather-resistant and easy-to-clean fluorosilicone-modified acrylic anti-graffiti coating comprises the following preparation steps:

[0043] (1) Hydrogenated silicone oil with an active hydrogen content of 0.75 wt % and a number average molecular weight of 6000 g / mol, APEG-1500, perfluorooctylethylene and toluene solvent are added to a reactor and mixed and dissolved uniformly, wherein the molar ratio of the active hydrogen content of the hydrogenated silicone oil to the added APEG-1500 and perfluorooctylethylene is 1:0.5:0.4. After nitrogen substitution, chloroplatinic acid catalyst is added, and the mixture is heated to 90° C. and stirred for reaction for 6 h. After the reaction is completed, the solvent and unreacted raw materials are removed in vacuo to obtain a polyether-modified fluorinated silicone oil.

[0044] (2) The polyether-modified fluorinated silicone oil was mixed with acryloyloxyethyl isocyanate and dibutyltin dilaurate catalyst, with the molar ratio of acryloyloxyethyl isocyanate to APEG-1500 being 1:1, and the mixture was heated to 70° C. and stirred for 6 h to obtain a polyether-modified fluorinated silicone oil containing double bonds.

[0045] (3) Add the double-bond polyether-modified fluorinated silicone oil, methacrylic acid, methyl methacrylate, isooctyl methacrylate monomers in a mass ratio of 30:100:20:10, nonylphenol polyoxyethylene ether (the concentration in the reaction solution is 3 wt %) and sodium dodecylbenzene sulfonate (1 wt %) into water, stir and emulsify evenly, heat to 75° C. under nitrogen protection, add ammonium persulfate solution dropwise and carry out copolymerization reaction for 5 h to obtain a weather-resistant and easy-to-clean fluorinated silicone modified acrylic anti-graffiti coating with a solid content of 65%.

[0046] Example 4

[0047] A method for preparing a weather-resistant and easy-to-clean fluorosilicone-modified acrylic anti-graffiti coating. Compared with Example 1, the molar ratio of the active hydrogen content of the hydrogen-containing silicone oil to APEG-500 and perfluorobutylethylene is adjusted to 1:0.2:0.7, and the rest is the same.

[0048] Example 5

[0049] A method for preparing a weather-resistant and easy-to-clean fluorosilicone-modified acrylic anti-graffiti coating. Compared with Example 1, the molar ratio of the active hydrogen content of the hydrogen-containing silicone oil to APEG-500 and perfluorobutylethylene is adjusted to 1:0.6:0.3, and the rest is the same.

[0050] Example 6

[0051] A method for preparing a weather-resistant and easy-to-clean fluorosilicone-modified acrylic anti-graffiti coating. Compared with Example 1, the molar ratio of the active hydrogen content of the hydrogen-containing silicone oil to APEG-500 and perfluorobutylethylene is adjusted to 1:0.1:0.5, and the rest is the same.

[0052] Example 7

[0053] A method for preparing a weather-resistant and easy-to-clean fluorosilicone-modified acrylic anti-graffiti coating. Compared with Example 1, the molar ratio of the active hydrogen content of the hydrogen-containing silicone oil to APEG-500 and perfluorobutylethylene is adjusted to 1:0.4:0.2, and the rest is the same.

[0054] The hydrophobicity (water contact angle), oleophobicity (hexadecane contact angle), adhesion (refer to GB / T 9286-2021), tensile strength, elongation at break and weather resistance (refer to JC / T 864-2008, the weather resistance test adopts artificial weathering treatment) of the anti-graffiti coating obtained in the above embodiment were tested, and the results are shown in Table 1 below.

[0055] Table 1

[0056]

[0057] It can be seen from the results in Table 1 that the fluorosilicone modified acrylic anti-graffiti coating obtained by the present invention has good hydrophobic and oleophobic properties and is easy to clean, and also has good adhesion, mechanical strength and weather resistance. And by controlling the active hydrogen content in the preparation process of the polyether-modified fluorosilicone oil containing double bonds and the molar ratio of allyl polyoxyethylene ether and perfluoroalkylethylene added to 1:0.2-0.6:0.3-0.7, a fluorosilicone modified acrylic anti-graffiti coating with a coating water contact angle of >100°, a hexadecane contact angle of ≥85°, an adhesion of grade 0, a tensile strength of >5MPa, an elongation at break of >300%, a tensile strength retention of >90%, and an elongation at break retention of >90% can be obtained.

[0058] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a weather-resistant and easy-to-clean fluorosilicone-modified acrylic anti-graffiti coating, characterized in that: The method comprises the following preparation steps: (1) adding hydrogen-containing silicone oil, allyl polyoxyethylene ether and perfluoroalkylethylene into an anhydrous solvent and mixing and dissolving them uniformly, then adding chloroplatinic acid catalyst and heating and stirring to react, and after the reaction is completed, removing the solvent in vacuo to obtain polyether-modified fluorinated silicone oil; (2) mixing the polyether-modified fluorinated silicone oil with (meth)acryloyloxyethyl isocyanate and an organic tin catalyst, heating and stirring to react, and obtaining a polyether-modified fluorinated silicone oil containing a double bond; (3) adding a polyether-modified fluorinated silicone oil containing a double bond, an acrylic monomer, an acrylate monomer and an emulsifier into water, stirring and emulsifying the mixture uniformly, heating the mixture to 60-90° C. under nitrogen protection, adding an initiator solution dropwise for copolymerization, and obtaining a weather-resistant and easy-to-clean fluorinated silicone-modified acrylic anti-graffiti coating; The active hydrogen content of the hydrogen-containing silicone oil is 0.2-1.5wt%, and the number average molecular weight is 2000-10000g / mol; the number average molecular weight of the allyl polyoxyethylene ether is 500-1500g / mol; the perfluoroalkylethylene is a perfluoroalkylethylene having 6-10 carbon atoms; The molar ratio of the active hydrogen content of the hydrogen-containing silicone oil to the added allyl polyoxyethylene ether and perfluoroalkylethylene is 1:0.2-0.6:0.3-0.

7.

2. The method for preparing a weather-resistant and easy-to-clean fluorosilicone modified acrylic anti-graffiti coating according to claim 1, characterized in that: The anhydrous solvent is toluene; the temperature of the heating and stirring reaction in step (1) is 80-90°C and the time is 4-8 hours; the temperature of the heating and stirring reaction in step (2) is 30-70°C and the time is 2-8 hours.

3. The method for preparing a weather-resistant and easy-to-clean fluorosilicone modified acrylic anti-graffiti coating according to claim 1, characterized in that: The molar ratio of the added amount of the (meth)acryloyloxyethyl isocyanate to the allyl polyoxyethylene ether is 0.8-1.2:

1.

4. The method for preparing a weather-resistant and easy-to-clean fluorosilicone modified acrylic anti-graffiti coating according to claim 1, characterized in that: The acrylic acid monomer is (meth)acrylic acid; the acrylic acid ester monomer is methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isooctyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate.

5. The method for preparing a weather-resistant and easy-to-clean fluorosilicone modified acrylic anti-graffiti coating according to claim 1, characterized in that: The mass ratio of the polyether-modified fluorinated silicone oil containing double bonds to the acrylic acid monomer and the acrylic ester monomer is 15-30:100:30-60.

6. The method for preparing a weather-resistant and easy-to-clean fluorosilicone modified acrylic anti-graffiti coating according to claim 1, characterized in that: The emulsifier is alkylphenol polyoxyethylene ether, alkyl alcohol polyoxyethylene ether sulfate, allyloxy alkylphenol polyoxyethylene ether, sodium alkyl sulfate, and alkylbenzene sulfonate.

7. The method for preparing a weather-resistant and easy-to-clean fluorosilicone modified acrylic anti-graffiti coating according to claim 1, characterized in that: The initiator is ammonium persulfate or potassium persulfate; the copolymerization reaction temperature is 60-80° C. and the reaction time is 2-8 hours.

8. A weather-resistant and easy-to-clean fluorosilicone modified acrylic anti-graffiti coating, characterized in that: It is prepared by the method according to any one of claims 1 to 7.

Images