CN111393985A - Modified polyurethane water-based paint and preparation method thereof - Google Patents

Modified polyurethane water-based paint and preparation method thereof Download PDF

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Publication number
CN111393985A
CN111393985A CN202010258943.XA CN202010258943A CN111393985A CN 111393985 A CN111393985 A CN 111393985A CN 202010258943 A CN202010258943 A CN 202010258943A CN 111393985 A CN111393985 A CN 111393985A
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parts
water
mixing
modified polyurethane
based paint
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CN111393985B (en
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陈绪芹
孟鸿
张天
陈鑫
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Foshan New Quantum Environmental Protection Material Co ltd
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Foshan New Quantum Environmental Protection Material Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
    • C09D175/04—Polyurethanes
    • C09D175/14—Polyurethanes having carbon-to-carbon unsaturated bonds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/08—Processes
    • C08G18/0804—Manufacture of polymers containing ionic or ionogenic groups
    • C08G18/0819—Manufacture of polymers containing ionic or ionogenic groups containing anionic or anionogenic groups
    • C08G18/0823—Manufacture of polymers containing ionic or ionogenic groups containing anionic or anionogenic groups containing carboxylate salt groups or groups forming them
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/08—Processes
    • C08G18/10—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
    • C08G18/12—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step using two or more compounds having active hydrogen in the first polymerisation step
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/4009—Two or more macromolecular compounds not provided for in one single group of groups C08G18/42 - C08G18/64
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/61—Polysiloxanes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/67—Unsaturated compounds having active hydrogen
    • C08G18/671—Unsaturated compounds having only one group containing active hydrogen
    • C08G18/672—Esters of acrylic or alkyl acrylic acid having only one group containing active hydrogen
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
    • C08G18/72—Polyisocyanates or polyisothiocyanates
    • C08G18/74—Polyisocyanates or polyisothiocyanates cyclic
    • C08G18/75—Polyisocyanates or polyisothiocyanates cyclic cycloaliphatic
    • C08G18/751—Polyisocyanates or polyisothiocyanates cyclic cycloaliphatic containing only one cycloaliphatic ring
    • C08G18/752—Polyisocyanates or polyisothiocyanates cyclic cycloaliphatic containing only one cycloaliphatic ring containing at least one isocyanate or isothiocyanate group linked to the cycloaliphatic ring by means of an aliphatic group
    • C08G18/753—Polyisocyanates or polyisothiocyanates cyclic cycloaliphatic containing only one cycloaliphatic ring containing at least one isocyanate or isothiocyanate group linked to the cycloaliphatic ring by means of an aliphatic group containing one isocyanate or isothiocyanate group linked to the cycloaliphatic ring by means of an aliphatic group having a primary carbon atom next to the isocyanate or isothiocyanate group
    • C08G18/755—Polyisocyanates or polyisothiocyanates cyclic cycloaliphatic containing only one cycloaliphatic ring containing at least one isocyanate or isothiocyanate group linked to the cycloaliphatic ring by means of an aliphatic group containing one isocyanate or isothiocyanate group linked to the cycloaliphatic ring by means of an aliphatic group having a primary carbon atom next to the isocyanate or isothiocyanate group and at least one isocyanate or isothiocyanate group linked to a secondary carbon atom of the cycloaliphatic ring, e.g. isophorone diisocyanate
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/08—Anti-corrosive paints
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/22—Luminous paints
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/20—Diluents or solvents
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/30—Sulfur-, selenium- or tellurium-containing compounds
    • C08K2003/3009—Sulfides
    • C08K2003/3027—Sulfides of cadmium
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/30—Sulfur-, selenium- or tellurium-containing compounds
    • C08K2003/3009—Sulfides
    • C08K2003/3036—Sulfides of zinc
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00—Specific properties of additives
    • C08K2201/002—Physical properties
    • C08K2201/003—Additives being defined by their diameter

Abstract

The invention provides a modified polyurethane water-based paint and a preparation method thereof, belonging to the technical field of water-based paints. The modified polyurethane water-based paint provided by the invention comprises: 50-55 parts of polyol, 20-25 parts of diisocyanate, 5-8 parts of hydrophilic chain extender, 8-10 parts of hydroxyl-terminated polysiloxane, 4-5 parts of end-capping agent, 3-5 parts of cross-linking agent, 5-7 parts of neutralizing agent, 0.3-0.5 part of free radical catalyst, 0.05-0.08 part of organic tin catalyst, 0.005-0.008 part of sodium borohydride, 0.03-0.05 part of mercaptopropionic acid, 7-14 parts of cadmium chloride, 6-12 parts of sodium sulfide, 5-10 parts of zinc chloride and 130-160 parts of water. The modified polyurethane water-based paint provided by the invention has the advantages of good raw material compatibility, high bonding strength with a substrate, high fluorescence intensity, good water resistance and corrosion resistance, high film-forming density and high hardness; meanwhile, water is used as a solvent, so that the environment is protected.

Description

Modified polyurethane water-based paint and preparation method thereof
Technical Field
The invention relates to the technical field of water-based paint, in particular to modified polyurethane water-based paint and a preparation method thereof.
Background
The polyurethane water-based paint is a green environment-friendly paint taking polyurethane as a base material and water as a dispersion medium. Compared with the traditional solvent type polyurethane, the polyurethane water-based paint not only retains the advantages of the traditional solvent type, but also has excellent performances of no toxicity, no combustion, environmental protection and the like, and is widely applied to the fields of paint, adhesive, leather finishing agent, surface treating agent and the like. However, the existing polyurethane water-based paint has poor viscosity and no fluorescent property, so that the application of the polyurethane water-based paint is limited.
Disclosure of Invention
The invention aims to provide a modified polyurethane water-based paint and a preparation method thereof.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a modified polyurethane water-based paint which is prepared from the following raw materials in parts by mass: 50-55 parts of polyol, 20-25 parts of diisocyanate, 5-8 parts of hydrophilic chain extender, 8-10 parts of hydroxyl-terminated polysiloxane, 4-5 parts of end-capping agent, 3-5 parts of cross-linking agent, 5-7 parts of neutralizing agent, 0.3-0.5 part of free radical catalyst, 0.05-0.08 part of organic tin catalyst, 0.005-0.008 part of sodium borohydride, 0.03-0.05 part of mercaptopropionic acid, 7-14 parts of cadmium chloride, 6-12 parts of sodium sulfide, 5-10 parts of zinc chloride and 130-160 parts of water.
Preferably, the free radical catalyst comprises a persulfate;
the crosslinking agent comprises trimethylolpropane glycidyl ether and/or polyazepine;
the hydrophilic chain extender comprises one or more of 1, 2-dihydroxy-3-propanesulfonic acid sodium salt, dimethylolpropionic acid and dimethylolbutyric acid;
the capping agent comprises hydroxyethyl acrylate and/or hydroxyethyl methacrylate.
Preferably, the polyol further comprises 0.005-0.008 parts of sodium borohydride and 0.03-0.05 parts of mercaptopropionic acid in parts by mass.
The invention also provides a preparation method of the modified polyurethane water-based paint in the technical scheme, which comprises the following steps:
mixing polyalcohol, diisocyanate, hydroxyl-terminated polysiloxane and an organic tin catalyst, and carrying out a first polymerization reaction to obtain a first prepolymer;
mixing the first prepolymer with a hydrophilic chain extender, and carrying out a second polymerization reaction to obtain a second prepolymer;
mixing the second prepolymer, a cross-linking agent and an end-capping reagent, and carrying out cross-linking reaction to obtain a third prepolymer;
mixing the third prepolymer, a neutralizing agent, a free radical catalyst, sodium borohydride, mercaptopropionic acid and part of water, and carrying out catalytic reaction to obtain polyurethane; the part of water accounts for 30-45% of the total amount of water
Mixing cadmium chloride, the first residual water and part of sodium sulfide, and carrying out a first double decomposition reaction to obtain a CdS quantum dot solution;
mixing the CdS quantum dot solution, zinc chloride, residual sodium sulfide and second residual water, and performing a second double decomposition reaction to obtain a CdS/ZnS quantum dot solution;
and mixing the polyurethane, the CdS/ZnS quantum dots and water, and carrying out blending reaction to obtain the modified polyurethane water-based paint.
Preferably, the temperature of the first polymerization reaction is 70-80 ℃ and the time is 4-6 h.
Preferably, the temperature of the second polymerization reaction is 80-90 ℃ and the time is 2-4 h.
Preferably, the temperature of the crosslinking reaction is 60-65 ℃, and the time is 4-6 h.
Preferably, the temperature of the catalytic reaction is 5-40 ℃, and the time is 1-2 h.
Preferably, the temperature of the first double decomposition reaction and the second double decomposition reaction is 70-80 ℃ independently, and the time is 1-2 h independently.
Preferably, the particle size of the CdS/ZnS quantum dot is 10-20 nm.
The invention provides a modified polyurethane water-based paint which is prepared from the following raw materials in parts by mass: 50-55 parts of polyol, 20-25 parts of diisocyanate, 5-8 parts of hydrophilic chain extender, 8-10 parts of hydroxyl-terminated polysiloxane, 4-5 parts of end-capping agent, 3-5 parts of cross-linking agent, 5-7 parts of neutralizing agent, 0.3-0.5 part of free radical catalyst, 0.05-0.08 part of organic tin catalyst, 0.005-0.008 part of sodium borohydride, 0.03-0.05 part of mercaptopropionic acid, 7-14 parts of cadmium chloride, 6-12 parts of sodium sulfide, 5-10 parts of zinc chloride and 130-160 parts of water. The modified polyurethane water-based paint provided by the invention takes the polyalcohol and the diisocyanate as main bodies and is obtained under the combined action of a hydrophilic chain extender, hydroxyl-terminated polysiloxane, a blocking agent, a cross-linking agent, a neutralizing agent, a free radical catalyst, sodium borohydride, mercaptopropionic acid, an organic tin catalyst, cadmium chloride, sodium sulfide and zinc chloride, and has the advantages of strong cohesiveness, high fluorescence intensity, good water resistance and corrosion resistance, high film-forming density and high hardness; meanwhile, water is used as a solvent, so that the environment is protected.
The preparation method of the modified polyurethane water-based paint provided by the invention is simple to operate and suitable for large-scale production.
Detailed Description
The invention provides a modified polyurethane water-based paint which is prepared from the following raw materials in parts by mass: 50-55 parts of polyol, 20-25 parts of diisocyanate, 5-8 parts of hydrophilic chain extender, 8-10 parts of hydroxyl-terminated polysiloxane, 4-5 parts of end-capping agent, 3-5 parts of cross-linking agent, 5-7 parts of neutralizing agent, 0.3-0.5 part of free radical catalyst, 0.05-0.08 part of organic tin catalyst, 0.005-0.008 part of sodium borohydride, 0.03-0.05 part of mercaptopropionic acid, 7-14 parts of cadmium chloride, 6-12 parts of sodium sulfide, 5-10 parts of zinc chloride and 130-160 parts of water.
In the present invention, all the raw material components are commercially available products well known to those skilled in the art unless otherwise specified.
In the invention, the raw materials for preparing the modified polyurethane water-based paint comprise 50-55 parts by mass of polyhydric alcohol, preferably 51-54 parts by mass, and more preferably 52-53 parts by mass. In the present invention, the polymeric polyol preferably includes one or more of polypropylene glycol, polyethylene glycol, polytetrahydrofuran glycol, 1, 6-hexanediol adipate and polycarbonate. In the present invention, the molecular weight of the polymeric polyol is preferably 1000 to 3000, more preferably 1500 to 2500. The polyol used in the invention has good low-temperature flexibility, weather resistance, water resistance, mechanical properties, thermal stability and the like, and further improves the water resistance, corrosion resistance, mechanical properties and compatibility of polyurethane.
In the invention, the raw materials for preparing the modified polyurethane water-based paint comprise 20-25 parts of diisocyanate, preferably 21-24 parts, and more preferably 2-23 parts by weight of the polyhydric alcohol. In the present invention, the diisocyanate preferably includes one or more of isophorone diisocyanate, toluene diisocyanate, 4-methylene-diphenyl diisocyanate, hexamethylene diisocyanate, 4-methylene-dicyclohexyl diisocyanate, and 4, 4-methylene-diisocyanate, and more preferably includes isophorone diisocyanate, toluene diisocyanate, 4-methylene-diphenyl diisocyanate, hexamethylene diisocyanate, 4-methylene-dicyclohexyl diisocyanate, or 4, 4-methylene-diisocyanate. The polyurethane synthesized by the diisocyanate adopted by the invention has excellent mechanical property, stability, chemical resistance and the like.
In the invention, the raw materials for preparing the modified polyurethane water-based paint comprise 5-8 parts of hydrophilic chain extender, preferably 5.5-7.5 parts, and more preferably 6-7 parts by mass of the polymeric polyol. In the present invention, the hydrophilic chain extender preferably includes one or more of sodium 1, 2-dihydroxy-3-propanesulfonate, dimethylolpropionic acid and dimethylolbutyric acid, and more preferably includes sodium 1, 2-dihydroxy-3-propanesulfonate, dimethylolpropionic acid or dimethylolbutyric acid. The invention adopts the hydrophilic chain extender, can increase the viscosity of the waterborne polyurethane, and further improves the water resistance, corrosion resistance, mechanical property and compatibility of the polyurethane.
In the invention, the raw materials for preparing the modified polyurethane water-based paint comprise 8-10 parts of hydroxyl-terminated polysiloxane, preferably 8.5-9.5 parts, and more preferably 9-9.5 parts by weight of the polyhydric alcohol. In the present invention, the hydroxyl-terminated polysiloxane preferably includes dimethylpolysiloxane, hydroxyl-terminated polysiloxane. The hydroxyl-terminated polysiloxane has the advantages of low surface energy, good hydrophobicity, good weather resistance and the like, and can be used as a functional monomer to introduce a hydrophilic chain segment and a water-resistant chain segment into a polyurethane molecule, so that the water resistance, the mechanical property and the compatibility of the polyurethane are improved.
In the invention, the raw materials for preparing the modified polyurethane water-based paint comprise 4-5 parts of end-capping reagent, preferably 4.2-4.8 parts, and more preferably 4.5-4.6 parts by weight of the polyhydric alcohol. In the present invention, the end-capping agent preferably comprises hydroxyethyl acrylate and/or hydroxyethyl methacrylate. In the present invention, when the end-capping reagent is hydroxyethyl acrylate and hydroxyethyl methacrylate, the amount ratio of hydroxyethyl acrylate to hydroxyethyl methacrylate is not particularly limited, and any ratio may be used.
In the invention, the raw materials for preparing the modified polyurethane water-based paint comprise 3-5 parts of cross-linking agent, preferably 3.5-4.5 parts, and more preferably 4-4.5 parts by weight based on the mass part of the polyhydric alcohol. In the present invention, the crosslinking agent preferably includes trimethylolpropane glycidyl ether and/or polyazepane. According to the invention, the added cross-linking agent can enable the polyol and the diisocyanate to be fully cross-linked, so that the water resistance, corrosion resistance, mechanical property and compatibility of the polyurethane are improved.
In the invention, the raw materials for preparing the modified polyurethane water-based paint comprise 5-7 parts of neutralizing agent, preferably 5.5-6.5 parts, and more preferably 6-6.5 parts by weight of the polyhydric alcohol. In the present invention, the neutralizing agent preferably includes one or more of triethylamine, triethanolamine, sodium hydroxide, N-methyldiethanolamine, methacrylic acid, and ammonia water, and more preferably triethylamine, triethanolamine, sodium hydroxide, N-methyldiethanolamine, methacrylic acid, or ammonia water. The concentration of the ammonia water in the present invention is not particularly limited, and any concentration may be used. When the neutralizer is ammonia water, the concentration of the ammonia water is preferably 10-15%.
In the invention, the raw materials for preparing the modified polyurethane water-based paint comprise 0.3-0.5 part of free radical catalyst, preferably 0.35-0.45 part of free radical catalyst, and more preferably 0.4-0.45 part of free radical catalyst by mass. In the present invention, the radical catalyst preferably comprises a persulfate salt, more preferably comprises ammonium persulfate and/or sodium persulfate.
In the invention, the raw materials for preparing the modified polyurethane water-based paint comprise 0.05-0.08 part of organic tin catalyst, preferably 0.06-0.07 part of polymeric polyol by mass. In the present invention, the organotin-based catalyst preferably includes dibutyltin dilaurate and/or stannous octoate. In the invention, the organic tin catalyst is environment-friendly and safe, has mild catalytic activity, is a very effective post-crosslinking accelerator, and improves the water resistance, mechanical property and compatibility of polyurethane.
In the invention, the raw materials for preparing the modified polyurethane water-based paint comprise 0.005-0.008 parts of sodium borohydride, preferably 0.005-0.007 parts of sodium borohydride, and more preferably 0.005-0.006 parts of polyatomic alcohol by mass.
In the invention, the raw materials for preparing the modified polyurethane water-based paint comprise 0.03-0.05 part of mercaptopropionic acid, preferably 0.03-0.045 part of mercaptopropionic acid, and more preferably 0.03-0.04 part of mercaptopropionic acid by mass.
In the invention, the raw materials for preparing the modified polyurethane water-based paint comprise 7-14 parts of cadmium chloride, more preferably 8-13 parts of cadmium chloride, and most preferably 10-12 parts of the polyatomic alcohol by mass. 12-19 parts of cadmium chloride, 5-8 parts of sodium sulfide, 5-8 parts of zinc chloride and 150-160 parts of water
In the invention, the raw materials for preparing the modified polyurethane water-based paint comprise 6-12 parts of sodium sulfide, more preferably 7-11 parts of sodium sulfide, and most preferably 8-10 parts of polyatomic alcohol by mass.
In the invention, the raw materials for preparing the modified polyurethane water-based paint preferably comprise 5-10 parts of zinc chloride, more preferably 6-9 parts of zinc chloride, and most preferably 7-8 parts of the polyatomic alcohol by mass.
In the invention, the raw materials for preparing the modified polyurethane water-based paint comprise 130-160 parts of water, preferably 135-155 parts of water, and more preferably 140-150 parts of water based on the mass parts of the polyhydric alcohol. In the present invention, the water is preferably deionized water. The invention takes water as solvent, does not add organic solvent, does not produce secondary pollution, and is green and environment-friendly.
The polyurethane prepared by using the polymeric polyol, the diisocyanate, the hydrophilic chain extender, the hydroxyl-terminated polysiloxane, the end-capping agent, the crosslinking agent, the neutralizing agent, the free radical catalyst, the sodium borohydride, the mercaptopropionic acid, the organic tin catalyst and the water as raw materials has good water resistance, high transparency and hardness and good compatibility with CdS/ZnS quantum dots; meanwhile, water is used as a solvent, so that the environment is protected.
The invention provides a preparation method of the modified polyurethane water-based paint in the technical scheme, which comprises the following steps:
mixing polyalcohol, diisocyanate, hydroxyl-terminated polysiloxane and an organic tin catalyst, and carrying out a first polymerization reaction to obtain a first prepolymer;
mixing the first prepolymer with a hydrophilic chain extender, and carrying out a second polymerization reaction to obtain a second prepolymer;
mixing the second prepolymer, a cross-linking agent and an end-capping reagent, and carrying out cross-linking reaction to obtain a third prepolymer;
mixing the third prepolymer, a neutralizing agent, a free radical catalyst, sodium borohydride, mercaptopropionic acid and part of water, and carrying out catalytic reaction to obtain polyurethane; the part of water accounts for 30-45% of the total amount of water;
mixing cadmium chloride, the first residual water and part of sodium sulfide, and carrying out a first double decomposition reaction to obtain a CdS quantum dot solution;
mixing the CdS quantum dot solution, zinc chloride, residual sodium sulfide and second residual water, and performing a second double decomposition reaction to obtain a CdS/ZnS quantum dot solution;
and mixing the polyurethane, the CdS/ZnS quantum dots and water, and carrying out blending reaction to obtain the modified polyurethane water-based paint.
The method comprises the steps of mixing the polyol, the diisocyanate, the hydroxyl-terminated polysiloxane and the organic tin catalyst, and carrying out a first polymerization reaction to obtain a first prepolymer.
In the present invention, the mixing is preferably stirring mixing, and the speed and time of the stirring mixing are not particularly limited in the present invention, and the raw materials may be uniformly mixed.
In the invention, the temperature of the first polymerization reaction is preferably 70-80 ℃, and more preferably 72-78 ℃; the time of the first polymerization reaction is preferably 4 to 6 hours, and more preferably 4.5 to 5.5 hours.
After the first prepolymer is obtained, the first prepolymer and a hydrophilic chain extender are mixed for a second polymerization reaction to obtain a second prepolymer.
In the present invention, the mixing is preferably stirring mixing, and the speed and time of the stirring mixing are not particularly limited in the present invention, and the raw materials may be uniformly mixed.
In the invention, the temperature of the second polymerization reaction is preferably 80-90 ℃, and more preferably 82-88 ℃; the time of the second polymerization reaction is preferably 2 to 4 hours, and more preferably 2.5 to 3.5 hours.
After the second prepolymer is obtained, the second prepolymer, the cross-linking agent and the end-capping reagent are mixed for cross-linking reaction to obtain a third prepolymer.
In the present invention, the mixing is preferably stirring mixing, and the speed and time of the stirring mixing are not particularly limited in the present invention, and the raw materials may be uniformly mixed.
In the invention, the temperature of the crosslinking reaction is preferably 60-65 ℃, and more preferably 62-64 ℃; the time of the crosslinking reaction is preferably 4-6 h, and more preferably 4.5-5.5 h.
After the third prepolymer is obtained, mixing the third prepolymer, a neutralizer, a free radical catalyst, sodium borohydride, mercaptopropionic acid and part of water, and carrying out catalytic reaction to obtain polyurethane; the part of water accounts for 30-45% of the total amount of water.
In the present invention, the portion of water further preferably accounts for 35 to 40% of the total amount of water.
In the invention, the third prepolymer, the neutralizing agent, the free radical catalyst, the sodium borohydride, the mercaptopropionic acid and part of water are preferably mixed in a mode that the third prepolymer and the neutralizing agent are mixed for 30-40 min, then the sodium borohydride, the mercaptopropionic acid and part of water are added and mixed for 15-20 min, and then the free radical catalyst is added and mixed. In the present invention, the mixing is preferably stirring mixing, and the speed of stirring mixing is not particularly limited in the present invention, and the raw materials may be uniformly mixed. In the invention, the water is preferably cold water, and the temperature of the cold water is preferably 10-15 ℃.
In the invention, the temperature of the catalytic reaction is preferably 5-40 ℃, and more preferably 20-25 ℃; the time of the catalytic reaction is preferably 1-2 hours, and more preferably 1-1.5 hours.
After the catalytic reaction is finished, the invention preferably performs solid-liquid separation on the obtained system of the catalytic reaction, extracts the obtained liquid, recovers the organic phase, and then concentrates the organic phase to obtain the polyurethane. The solid-liquid separation method of the present invention is not particularly limited, and a solid-liquid separation method known in the art may be used, specifically, filtration or centrifugation. In the present invention, the extractant used for the extraction preferably comprises dichloromethane and chloroform. The concentration method of the present invention is not particularly limited, and a concentration method known in the art may be used.
According to the invention, the polyurethane prepared by using the polyhydric alcohol and the diisocyanate as main bodies under the combined action of the hydrophilic chain extender, the hydroxyl-terminated polysiloxane, the end-capping reagent, the cross-linking agent, the neutralizing agent, the free radical catalyst, the sodium borohydride, the mercaptopropionic acid and the organic tin catalyst has high transparency, good mechanical property and good compatibility with CdS/ZnS quantum dots; hydroxyl contained in hydroxyl-terminated polysiloxane in polyurethane can improve the bonding strength of the coating and a substrate; and water is used as a solvent, so that the environment is protected. The preparation method of the polyurethane provided by the invention is simple to operate and suitable for industrial production.
Cadmium chloride, first residual water and part of sodium sulfide are mixed to carry out a first double decomposition reaction, and a CdS quantum dot solution is obtained.
The proportion of the part of sodium sulfide to the total amount of the sodium sulfide is not particularly limited, and the molar ratio of cadmium chloride to the part of sodium sulfide can be ensured to be 1-2: 1-2.
In the present invention, the mixing of the cadmium chloride, the first remaining water and a part of the sodium sulfide preferably comprises mixing CdCl2Mixing with the first residual water I to obtain CdCl2A solution; part of Na is removed2S and the first residual water II are mixed to obtain first Na2S solution; the CdCl is added2Adjusting the pH value of the solution to 8-9, and adding Na2And (4) mixing the S solution.
In the present invention, the CdCl2The concentration of the solution is preferably 2-3 mol/L, more preferably 2-2.5 mol/L. in the invention, the Na2The concentration of the S solution is preferably 2-3 mol/L, more preferably 2-2.5 mol/L2The aqueous solution of S is preferably added dropwise. The present invention is directed to said Na2The dropping rate of the two times of addition of the aqueous solution of S is not particularly limited, and a dropping rate well known in the art may be employed.
In the invention, the alkaline reagent used for adjusting the pH value to 8-9 is not particularly limited, and hydroxide well known in the art can be used; in the examples of the present invention, sodium hydroxide is preferably used to adjust the pH. In the invention, the temperature of the first double decomposition reaction is preferably 70-80 ℃, more preferably 72-78 ℃, and the time is preferably 1-2 h, more preferably 1.5-2 h.
After the CdS quantum dot solution is obtained, the CdS quantum dot solution, zinc chloride, residual sodium sulfide and second residual water are mixed to perform a second double decomposition reaction, so that the CdS/ZnS quantum dot solution is obtained.
In the invention, the mass ratio of the first residual water to the second residual water is preferably 1-2: 1-2.
In the present invention, mixing the CdS quantum dot solution, zinc chloride, remaining sodium sulfide and second remaining water preferably comprises mixing ZnCl2Mixing with the second residual water I to obtain ZnCl2A solution; na will remain2S and the second residual water II are mixed to obtain second Na2S solution; adjusting the pH value of the CdS quantum dot solution to 8-9, and adding Na2And (4) mixing the S solution.
In the present invention, the ZnCl is2The concentration of the solution is preferably 2-3 mol/L, more preferably 2-2.5 mol/L. in the invention, the second Na2The concentration of the S solution is preferably 2-3 mol/L, more preferably 2-2.5 mol/L2The aqueous solution of S is preferably added dropwise. The present invention is directed to said Na2The dropping rate of the two times of addition of the aqueous solution of S is not particularly limited, and a dropping rate well known in the art may be employed. The alkaline reagent used for adjusting the pH value to 8-9 is not particularly limited, and hydroxide well known in the art can be used; in the examples of the present invention, sodium hydroxide is preferably used to adjust the pH.
In the invention, the temperature of the second double decomposition reaction is preferably 70-80 ℃, more preferably 72-78 ℃, and the time is preferably 1-2 h, more preferably 1.5-2 h.
After the solution of polyurethane and CdS/ZnS quantum dots is obtained, the polyurethane, the CdS/ZnS quantum dots and water are mixed and subjected to blending reaction to obtain the modified polyurethane water-based paint.
In the present invention, the mixing is preferably stirring mixing, and the speed of stirring mixing is not particularly limited in the present invention, and the raw materials may be uniformly mixed.
In the invention, the temperature of the blending reaction is preferably 95-105 ℃, and more preferably 100-105 ℃; the time of the blending reaction is preferably 7-10 hours, and more preferably 8-9 hours.
The invention takes the prepared polyurethane as a main body and CdS/ZnS quantum dots as active fluorescent functional groups, and the interaction between the molecules of the polyurethane and the CdS/ZnS quantum dots is stronger, and the bond energy is large, so that the modified polyurethane water-based paint has high hardness, good waterproof performance and high fluorescent intensity after being formed into a film; and the hydroxyl contained in the hydroxyl-terminated polysiloxane in the polyurethane can improve the bonding strength of the coating and the substrate. The modified polyurethane water-based paint has the advantages that the polyurethane is used as a main body, the CdS/ZnS quantum dots are used as active fluorescent dots, and water is used as a solvent, so that the obtained modified polyurethane water-based paint has strong cohesiveness, high fluorescence intensity, good water resistance and corrosion resistance, high density of formed films and high hardness; and water is used as a solvent, so that the environment is protected. The preparation method of the modified polyurethane water-based paint provided by the invention is simple to operate and suitable for industrial production.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
(1) The polyurethane comprises the following raw materials in parts by weight: 23 parts of isophorone diisocyanate, 47 parts of dihydric alcohol, 10 parts of hydroxyl-terminated polysiloxane, 0.05 part of an organotin catalyst, 4 parts of dimethylolpropionic acid hydrophilic chain extender, 4.3 parts of hydroxyethyl methacrylate end-capping agent, 3.7 parts of triethylamine, 0.4 part of ammonium persulfate, 5 parts of polyaziridine cross-linking agent, 0.005 part of sodium borohydride, 0.03 part of mercaptopropionic acid, 7 parts of cadmium chloride, 6 parts of sodium sulfide, 5 parts of zinc chloride and 130 parts of deionized water.
Adding isophorone diisocyanate, dihydric alcohol, hydroxyl-terminated polysiloxane and an organic tin catalyst into a reactor, stirring and mixing uniformly, heating to 80 ℃, and reacting for 4 hours to obtain a first prepolymer; mixing the first prepolymer and dimethylolpropionic acid, heating to 85 ℃, reacting for 2 hours to obtain a second prepolymer, cooling the second prepolymer to 60 ℃, adding hydroxyethyl methacrylate, and reacting for 4 hours at 60 ℃ to obtain a third prepolymer; and cooling the third prepolymer to room temperature, adding triethylamine, stirring and mixing for 30min, adding deionized water at 10 ℃, stirring and mixing for 15min, adding ammonium persulfate, and extracting the obtained reaction system to obtain the polyurethane.
(2) Adding CdCl2Mixing with water to obtain CdCl2Aqueous solution (concentration 2 mol/L) and adding Na2S is mixed with water to obtain Na2Aqueous S solution (concentration 2 mol/L) and ZnCl2Mixing with water to obtain ZnCl2Aqueous solution (concentration 2 mol/L) and sodium hydroxide is used to react the CdCl2The pH value of the solution is adjusted to 8.5, and Na is added dropwise2Stirring and mixing the S aqueous solution, and carrying out a first double decomposition reaction at 75 ℃ to obtain a CdS quantum dot aqueous solution; mixing the CdS quantum dot aqueous solution and ZnCl2Stirring and mixing the aqueous solution, adjusting the pH value of the obtained mixed solution to 8.5 by using sodium hydroxide, and then adding Na dropwise2Mixing S aqueous solution, and carrying out second double decomposition reaction at 75 ℃ to obtain CdS/ZnS quantum dot solution, wherein CdCl2、Na2S and ZnCl2In a molar ratio of 1:2: 0.5.
(3) And mixing the polyurethane and the CdS/ZnS quantum dot solution, and reacting for 7h at 100 ℃ to obtain the modified polyurethane water-based paint, wherein the mass ratio of the CdS/ZnS quantum dots to the polyurethane is 1: 2.
The modified polyurethane water-based paint is coated on the clean iron metal surface and dried for 20min at the temperature of 150 ℃, and the thickness of the obtained coating film is 15 mu m.
The hardness is measured by a GB/T6739-2006 pencil method, the hardness of the modified polyurethane water-based paint coating is 3H, and the adhesion of the coating is 3B.
The salt spray resistance is determined by GB/T1771-2007 color paint and varnish neutral salt spray resistance, and the salt spray resistance of the modified polyurethane water-based paint coating film is not foamed and rusted after more than 250 hours.
The wet heat resistance time of the modified polyurethane water-based paint coating is 7 days.
Example 2
(1) The polyurethane comprises the following raw materials in parts by weight: 20 parts of isophorone diisocyanate, 50 parts of dihydric alcohol, 8 parts of hydroxyl-terminated polysiloxane, 0.04 part of an organotin catalyst, 3.5 parts of dimethylolpropionic acid hydrophilic chain extender, 4.5 parts of hydroxyethyl methacrylate end-capping agent, 4 parts of triethylamine, 0.6 part of ammonium persulfate, 3 parts of polyaziridine cross-linking agent, 0.005 part of sodium borohydride, 0.03 part of mercaptopropionic acid, 10 parts of cadmium chloride, 10 parts of sodium sulfide, 8 parts of zinc chloride and 140 parts of deionized water.
Adding isophorone diisocyanate, dihydric alcohol, hydroxyl-terminated polysiloxane and an organic tin catalyst into a reactor, stirring and mixing uniformly, heating to 80 ℃, and reacting for 4 hours to obtain a first prepolymer; mixing the first prepolymer and dimethylolpropionic acid, heating to 85 ℃, reacting for 2 hours to obtain a second prepolymer, cooling the second prepolymer to 60 ℃, adding hydroxyethyl methacrylate, and reacting for 4 hours at 60 ℃ to obtain a third prepolymer; and cooling the third prepolymer to room temperature, adding triethylamine, stirring and mixing for 30min, adding deionized water at 10 ℃, stirring and mixing for 15min, adding ammonium persulfate, and extracting the obtained reaction system to obtain the polyurethane.
(2) Adding CdCl2Mixing with water to obtain CdCl2Aqueous solution (concentration 2 mol/L) and adding Na2S is mixed with water to obtain Na2Aqueous S solution (concentration 2 mol/L) and ZnCl2Mixing with water to obtain ZnCl2Aqueous solution (concentration 2 mol/L) and sodium hydroxide is used to react the CdCl2Adjusting the pH value of the solution to 8-9, and then dropwise adding Na2Stirring and mixing the S aqueous solution, and carrying out a first double decomposition reaction at 75 ℃ to obtain a CdS quantum dot aqueous solution; will be described inCdS quantum dot aqueous solution and ZnCl2Stirring and mixing the aqueous solution, adjusting the pH value of the obtained mixed solution to 8-9 by using sodium hydroxide, and then dropwise adding Na2Mixing S aqueous solution, and carrying out second double decomposition reaction at 75 ℃ to obtain CdS/ZnS quantum dot solution, wherein CdCl2、Na2S and ZnCl2In a molar ratio of 1:2: 0.5.
(3) Mixing the polyurethane and a CdS/ZnS quantum dot solution (the concentration is 2 mol/L), and reacting for 7h at 100 ℃ to obtain the modified polyurethane water-based paint, wherein the mass ratio of the CdS/ZnS quantum dots to the polyurethane is 1:2
The modified polyurethane water-based paint is coated on the clean iron metal surface and dried for 30min at the temperature of 150 ℃, and the thickness of the obtained coating film is 15 mu m.
The hardness is measured by a GB/T6739-2006 pencil method, the hardness of the modified polyurethane water-based paint coating is 3H, and the adhesion of the coating is 3B.
The salt spray resistance is determined by GB/T1771-2007 color paint and varnish neutral salt spray resistance, and the salt spray resistance of the modified polyurethane water-based paint coating film is not foamed and rusted after more than 240 hours.
The wet heat resistance time of the modified polyurethane water-based paint coating is 7 days.
Example 3
(1) The polyurethane comprises the following raw materials in parts by weight: 23 parts of isophorone diisocyanate, 47 parts of dihydric alcohol, 10 parts of hydroxyl-terminated polysiloxane, 0.05 part of an organotin catalyst, 4 parts of dimethylolpropionic acid hydrophilic chain extender, 4.3 parts of hydroxyethyl methacrylate end-capping agent, 3.7 parts of triethylamine, 0.4 part of ammonium persulfate, 5 parts of polyaziridine cross-linking agent, 0.006 part of sodium borohydride, 0.04 part of mercaptopropionic acid, 14 parts of cadmium chloride, 12 parts of sodium sulfide, 10 parts of zinc chloride and 160 parts of deionized water.
Adding isophorone diisocyanate, dihydric alcohol, hydroxyl-terminated polysiloxane and an organic tin catalyst into a reactor, stirring and mixing uniformly, heating to 80 ℃, and reacting for 4 hours to obtain a first prepolymer; mixing the first prepolymer and dimethylolpropionic acid, heating to 85 ℃, reacting for 2 hours to obtain a second prepolymer, cooling the second prepolymer to 60 ℃, adding hydroxyethyl methacrylate, and reacting for 4 hours at 60 ℃ to obtain a third prepolymer; and (3) cooling the third prepolymer to room temperature, adding triethylamine, stirring and mixing for 30min, adding deionized water at 10 ℃, stirring and mixing for 15min, adding ammonium persulfate, and then carrying out the obtained reaction system to obtain the polyurethane.
(2) Adding CdCl2Mixing with water to obtain CdCl2Aqueous solution (concentration 2 mol/L) and adding Na2S is mixed with water to obtain Na2Aqueous S solution (concentration 2 mol/L) and ZnCl2Mixing with water to obtain ZnCl2Aqueous solution (concentration 2 mol/L) and sodium hydroxide is used to react the CdCl2Adjusting the pH value of the solution to 8-9, and then dropwise adding Na2Stirring and mixing the S aqueous solution, and carrying out a first double decomposition reaction at 75 ℃ to obtain a CdS quantum dot aqueous solution; mixing the CdS quantum dot aqueous solution and ZnCl2Stirring and mixing the aqueous solution, adjusting the pH value of the obtained mixed solution to 8-9 by using sodium hydroxide, and then dropwise adding Na2Mixing S aqueous solution, and carrying out second double decomposition reaction at 75 ℃ to obtain CdS/ZnS quantum dot solution, wherein CdCl2、Na2S and ZnCl2In a molar ratio of 1:2: 0.5.
(3) And mixing the polyurethane with a CdS/ZnS quantum dot solution (the concentration is 2 mol/L), and reacting for 7h at 100 ℃ to obtain the modified polyurethane water-based paint, wherein the mass ratio of the CdS/ZnS quantum dots to the polyurethane is 1: 2.
The modified polyurethane water-based paint is coated on the clean iron metal surface and dried for 30min at the temperature of 150 ℃, and the thickness of the obtained coating film is 15 mu m.
The hardness is measured by a GB/T6739-2006 pencil method, the hardness of the coating film of the modified polyurethane water-based paint is 3H, and the adhesion force of the coating film is 3B
The salt spray resistance is determined by GB/T1771-2007 color paint and varnish neutral salt spray resistance, and the salt spray resistance of the modified polyurethane water-based paint coating film is not foamed and rusted after more than 240 hours.
The wet heat resistance time of the modified polyurethane water-based paint coating is 7 days.
Comparative example 1
An aqueous coating was prepared according to the method of example 1, except that no CdS/ZnS quantum dots were added to obtain a polyurethane aqueous coating.
The polyurethane water-based paint is coated on a clean iron metal surface and dried for 30min at the temperature of 150 ℃, and the thickness of the obtained coating film is 15 mu m.
The hardness is measured by a GB/T6739-2006 pencil method, the hardness of the modified polyurethane water-based paint coating is 2H, and the adhesion force of the coating is 3B
The salt spray resistance is determined by GB/T1771-2007 color paint and varnish neutral salt spray resistance, and the salt spray resistant heavy rain 245h of the modified polyurethane water-based paint coating film does not bubble and does not rust.
The wet heat resistance time of the modified polyurethane water-based paint coating is 6 days.
Comparative example 2
The modified polyurethane aqueous coating material was prepared according to the method of example 1, which is different from example 1 in that the mass ratio of polyurethane to CdS/ZnS quantum dots was 1: 0.5.
The modified polyurethane water-based paint is coated on the clean iron metal surface and dried for 30min at the temperature of 150 ℃, and the thickness of the obtained coating film is 15 mu m.
The hardness is measured by a GB/T6739-2006 pencil method, the hardness of the modified polyurethane water-based paint coating is 2H, and the adhesion force of the coating is 2B.
The salt spray resistance is determined by GB/T1771-2007 color paint and varnish neutral salt spray resistance, and the salt spray resistance of the modified polyurethane water-based paint coating film is not foamed and rusted after more than 230 hours.
The wet heat resistance time of the modified polyurethane water-based paint coating is 6 days.
Comparative example 3
The modified polyurethane aqueous coating material was prepared according to the method of example 1, which is different from example 1 in that the mass ratio of polyurethane to CdS/ZnS quantum dots was 6: 1.
The modified polyurethane water-based paint is coated on the clean iron metal surface and dried for 30min at the temperature of 150 ℃, and the thickness of the obtained coating film is 15 mu m.
The hardness is measured by a GB/T6739-2006 pencil method, the hardness of the coating film of the modified polyurethane water-based paint is 2H, and the adhesion force of the coating film is 2B
The salt spray resistance is determined by GB/T1771-2007 color paint and varnish neutral salt spray resistance, and the salt spray resistance of the modified polyurethane water-based paint coating film is not foamed and rusted after more than 245 h.
The wet heat resistance time of the modified polyurethane water-based paint coating is 6 days.
In conclusion, the modified polyurethane water-based paint prepared by using polyurethane and CdS/ZnS quantum dots as raw materials and water as a solvent has the advantages of excellent hydrophobic property, high hardness, strong adhesion to a substrate and strong fluorescence.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. The modified polyurethane water-based paint is characterized by being prepared from the following raw materials in parts by mass: 50-55 parts of polyol, 20-25 parts of diisocyanate, 5-8 parts of hydrophilic chain extender, 8-10 parts of hydroxyl-terminated polysiloxane, 4-5 parts of end-capping agent, 3-5 parts of cross-linking agent, 5-7 parts of neutralizing agent, 0.3-0.5 part of free radical catalyst, 0.05-0.08 part of organic tin catalyst, 0.005-0.008 part of sodium borohydride, 0.03-0.05 part of mercaptopropionic acid, 7-14 parts of cadmium chloride, 6-12 parts of sodium sulfide, 5-10 parts of zinc chloride and 130-160 parts of water.
2. The modified polyurethane waterborne coating of claim 1, wherein the free radical catalyst comprises a persulfate;
the crosslinking agent comprises trimethylolpropane glycidyl ether and/or polyazepine.
3. The modified polyurethane waterborne coating of claim 1 or 2, wherein the hydrophilic chain extender comprises one or more of 1, 2-dihydroxy-3-propanesulfonic acid sodium salt, dimethylolpropionic acid and dimethylolbutyric acid;
the capping agent comprises hydroxyethyl acrylate and/or hydroxyethyl methacrylate.
4. The preparation method of the modified polyurethane water-based paint as described in any one of claims 1 to 3, characterized by comprising the following steps:
mixing polyalcohol, diisocyanate, hydroxyl-terminated polysiloxane and an organic tin catalyst, and carrying out a first polymerization reaction to obtain a first prepolymer;
mixing the first prepolymer with a hydrophilic chain extender, and carrying out a second polymerization reaction to obtain a second prepolymer;
mixing the second prepolymer, a cross-linking agent and an end-capping reagent, and carrying out cross-linking reaction to obtain a third prepolymer;
mixing the third prepolymer, a neutralizing agent, a free radical catalyst, sodium borohydride, mercaptopropionic acid and part of water, and carrying out catalytic reaction to obtain polyurethane; the part of water accounts for 30-45% of the total amount of water;
mixing cadmium chloride, the first residual water and part of sodium sulfide, and carrying out a first double decomposition reaction to obtain a CdS quantum dot solution;
mixing the CdS quantum dot solution, zinc chloride, residual sodium sulfide and second residual water, and performing a second double decomposition reaction to obtain a CdS/ZnS quantum dot solution;
and mixing the polyurethane, the CdS/ZnS quantum dots and water, and carrying out blending reaction to obtain the modified polyurethane water-based paint.
5. The method according to claim 4, wherein the first polymerization reaction is carried out at a temperature of 70 to 80 ℃ for 4 to 6 hours.
6. The method according to claim 4, wherein the second polymerization reaction is carried out at a temperature of 80 to 90 ℃ for 2 to 4 hours.
7. The preparation method according to claim 4, wherein the temperature of the crosslinking reaction is 60-65 ℃ and the time is 4-6 h.
8. The preparation method according to claim 4, wherein the temperature of the catalytic reaction is 5-40 ℃ and the time is 1-2 h.
9. The method of claim 4, wherein the first and second metathesis reactions are independently carried out at a temperature of 70 to 80 ℃ for 1 to 2 hours.
10. The preparation method according to claim 4, wherein the CdS/ZnS quantum dots have a particle size of 10-20 nm.
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