High-hardness water-based paint and preparation method thereof

Abstract

The invention discloses a high-hardness water-based paint and a preparation method thereof, and belongs to the technical field of paints.The high-hardness water-based paint is prepared from, by weight, 50-80 parts of modified water-based alkyd resin, 10-15 parts of nano-silica modified water-based epoxy resin, 2-8 parts of coalescing agent, 10-15 parts of pigment, 5-8 parts of filler, 0.5-0.8 part of dispersing agent, 0.1-0.3 part of defoaming agent, 0.1-0.5 part of flatting agent and 20-35 parts of water; the high-hardness water-based paint prepared by the invention has the characteristics of high hardness, good toughness, good water resistance, high adhesive force and high stability, and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and in particular relates to a high-hardness water-based coating and a preparation method thereof. Background Art

[0002] Water-based paint is a paint that uses water as a solvent. Its main ingredients include polymer emulsions, pigments, fillers and additives. After painting, the water evaporates and the film-forming substances cross-link and solidify to form a paint film. Because of its environmental friendliness, low flammability and low volatile organic compound emissions, it is widely used in construction, furniture, automobiles and other fields.

[0003] At present, the conventionally selected resins of water-based coatings include water-based acrylic resins, water-based polyurethane resins, water-based epoxy resins and water-based alkyd resins, among which water-based alkyd resins have low cost, a wide range of raw material sources, and good gloss, fullness and flexibility, and are therefore widely used. However, water-based alkyd resins contain more polar groups such as ester bonds and hydroxyls in their molecular chains, the forces between these groups are relatively weak, and the rigidity of the molecular chains is relatively poor, and their cross-linking density is relatively low, making it difficult to form a highly cross-linked compact structure like some high-performance resins, thereby affecting the hardness of the paint film; on the other hand, the ester bonds on the alkyd resins are prone to hydrolysis in water, especially under high temperature and high humidity environments, where hydrolysis can cause the resin molecular chains to break, the molecular weight to decrease, and the mechanical properties of the paint film to decrease, the hardness to decrease, and the paint film to appear powdering, peeling, and the like. Therefore, how to prepare a high-hardness water-based alkyd resin coating by modifying it is of great significance for extending the use effect and service life of the coating. Summary of the invention

[0004] To solve the above problems, the object of the present invention is to provide a high-hardness water-based coating and a preparation method thereof.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0006] A high-hardness water-based paint, composed of the following raw materials, by weight: 50-80 parts of modified water-based alkyd resin, 10-15 parts of nano-silicon dioxide modified water-based epoxy resin, 2-8 parts of film-forming aid, 10-15 parts of pigment, 5-8 parts of filler, 0.5-0.8 parts of dispersant, 0.1-0.3 parts of defoamer, 0.1-0.5 parts of leveling agent and 20-35 parts of water;

[0007] The modified waterborne alkyd resin is prepared by modifying an alkyd resin with a modified styrene-maleic anhydride copolymer, wherein a polyetheramine is grafted onto the modified styrene-maleic anhydride copolymer;

[0008] The modified styrene-maleic anhydride copolymer is prepared according to the following method:

[0009] Add styrene-maleic anhydride copolymer to cyclohexanone, stir to dissolve, then add polyetheramine, stir to react at 90-100° C. for 2-5 hours, and then remove the solvent by distillation under reduced pressure to obtain a modified styrene-maleic anhydride copolymer.

[0010] The mass ratio of the styrene-maleic anhydride copolymer, cyclohexanone and polyetheramine is 1:5-10:1.5-2.5.

[0011] The polyetheramine is polyetheramine ED-600 or polyetheramine ED-900.

[0012] The film-forming aid is propylene glycol monoether, dipropylene glycol butyl ether or diethylene glycol monobutyl ether.

[0013] The pigment is titanium white, iron oxide yellow, iron red, iron blue or carbon black.

[0014] The filler is calcium carbonate, talc or zinc phosphate.

[0015] The dispersant is sodium polyacrylate or fatty alcohol polyoxyethylene ether.

[0016] The defoamer is an organosilicon defoamer or polyoxypropylene oxyethylene glycerol ether.

[0017] The leveling agent is polyacrylic acid or silicone leveling agent.

[0018] The preparation method of the modified waterborne alkyd resin comprises the following steps:

[0019] In parts by weight, 12 to 20 parts of linoleic acid, 10 to 15 parts of trimethylolpropane, 8 to 12 parts of phthalic anhydride, 3 to 5 parts of modified styrene-maleic anhydride copolymer and 1 to 2 parts of xylene are added to a reactor, stirred and heated to 180°C, kept warm for reaction for 1 to 3 hours, heated to 190 to 230°C for reaction for 3 to 8 hours, reacted until the acid value reached 10 to 15 mgKOH / g, vacuumed to remove the xylene, cooled to 180°C, added 3 to 5 parts of trimellitic anhydride, continued to keep warm for reaction until the acid value reached 35 to 50 mgKOH / g, cooled to 60 to 80°C, added 4 to 5 parts of triethylamine for neutralization reaction for 0.5 to 1 hour, finally added water for high-speed emulsification dispersion for 30 minutes, filtered, and obtained a modified waterborne alkyd resin.

[0020] The nano-silicon dioxide modified waterborne epoxy resin is prepared according to the following method:

[0021] 1) Add nano-silicon dioxide to an organic solvent with a water content of less than 10 ppm, then add 3-chloropropyltriethoxysilane, heat to 40-50° C., and stir to react for 10-24 hours to obtain silanized silicon dioxide;

[0022] 2) adding the silanized silicon dioxide, bisphenol A epoxy resin and sodium hydride prepared in step 1) into tetrahydrofuran, stirring and mixing evenly, heating to 50-80° C., reacting for 3-5 hours, adding water to quench the reaction after the reaction is completed, then adding dichloromethane for extraction, and distilling the obtained organic layer under reduced pressure to remove the solvent to obtain nano-silicon dioxide modified epoxy resin;

[0023] 3) Add the nano-silica modified epoxy resin and water-based epoxy emulsifier obtained in step 2) into a reactor, disperse them uniformly at high speed at 50-55° C., then drop water thereinto, stir and disperse for 0.5-1 h, and obtain the nano-silica modified water-based epoxy resin.

[0024] The organic solvent in step 1) is tetrahydrofuran or toluene.

[0025] The mass ratio of the nano-silicon dioxide, the organic solvent and 3-chloropropyltriethoxysilane in step 1) is 1:5-10:2-4.

[0026] The mass ratio of the silanized silicon dioxide, bisphenol A epoxy resin, sodium hydride, tetrahydrofuran, water and dichloromethane in step 2) is 0.2-0.4:1:0.1-0.2:5-10:3-5:3-5.

[0027] The mass ratio of the nano-silica modified epoxy resin, the water-based epoxy emulsifier and water in step 3) is 1:0.1-0.2:0.7-0.9.

[0028] The method for preparing the high-hardness water-based coating comprises the following steps:

[0029] In parts by weight, 50-80 parts of modified water-based alkyd resin, 10-15 parts of pigment, 5-8 parts of filler, 0.5-0.8 parts of dispersant and 20-35 parts of water are added into a high-speed disperser, and the mixture is stirred and dispersed evenly at 1500-2000 r / min. Then 10-15 parts of nano-silicon dioxide modified water-based epoxy resin are added thereto, and the mixture is stirred and reacted for 10-30 minutes. Finally, 2-8 parts of film-forming aid, 0.1-0.3 parts of defoaming agent and 0.1-0.5 parts of leveling agent are added, and the mixture is stirred and dispersed at 500-800 r / min for 0.5-1 hour to obtain a high-hardness water-based coating.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] The high-hardness water-based paint of the present invention comprises a water-based epoxy resin modified by nano-silicon dioxide and a modified water-based alkyd resin. The water-based alkyd resin is modified by using a modified styrene-maleic anhydride copolymer. The epoxy group can react with the active amine group in the modified styrene-maleic anhydride copolymer to form a stable three-dimensional network structure. The rigid structure of styrene can improve the hardness and glass transition temperature of the paint, thereby increasing the mechanical strength of the water-based paint. Meanwhile, the cross-linked network structure blocks the ester group in the alkyd resin, thereby reducing hydrolysis and increasing the stability of the paint. The epoxy resin is modified by using nano-silicon dioxide, thereby increasing the compatibility between the nano-silicon dioxide and the resin, allowing the nano-silicon dioxide to be more stably dispersed in the paint, thereby further increasing the hardness of the paint.

[0032] The high-hardness water-based paint of the present invention utilizes the reaction of polyetheramine and maleic anhydride groups to form amide bonds, and at the same time introduces flexible ether chains, thereby improving the toughness of the water-based paint and the adhesion to the substrate; at the same time, the water solubility of the styrene-maleic anhydride copolymer can be improved; due to the hydrophobicity of styrene and silane chains, the water absorption rate of the water-based paint can be reduced after film formation, the water resistance can be improved, and the occurrence of hydrolysis reaction can be reduced.

[0033] The high-hardness water-based paint prepared by the invention has the characteristics of high hardness, good toughness, good water resistance, high adhesion and high stability, and has broad application prospects. DETAILED DESCRIPTION

[0034] In order to better understand the technical solution of the present invention, the above content of the present invention is further described in detail below through specific implementation methods in the form of embodiments, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples. All technologies realized based on the above content of the present invention belong to the scope of the present invention.

[0035] Example 1 Preparation of modified styrene maleic anhydride copolymer

[0036] 0.1 kg of styrene-maleic anhydride copolymer was added to 0.5 kg of cyclohexanone, and after stirring to dissolve, 0.15 kg of polyetheramine ED-600 was added. After stirring and reacting at 90° C. for 5 hours, the solvent was removed by reduced pressure distillation to obtain a modified styrene-maleic anhydride copolymer.

[0037] Preparation of modified waterborne alkyd resin

[0038] 1.2kg of linolenic acid, 1kg of trimethylolpropane, 0.8kg of phthalic anhydride, 0.3kg of modified styrene-maleic anhydride copolymer and 0.1kg of xylene were added into the reactor, heated to 180°C with stirring, and kept warm for reaction for 1h, then heated to 190°C for reaction for 8h, and reacted until the acid value reached 15mgKOH / g, vacuumed to remove the xylene, cooled to 180°C, added with 0.3kg of trimellitic anhydride, and kept warm for reaction until the acid value reached 35mgKOH / g, cooled to 60°C, added with 0.4kg of triethylamine for neutralization reaction for 0.5h, and finally added with water for high-speed emulsification dispersion for 30min, filtered, and obtained a modified waterborne alkyd resin.

[0039] Preparation of waterborne epoxy resin modified by nano-silicon dioxide

[0040] 1) Add 1 kg of nano-silicon dioxide to 5 kg of tetrahydrofuran with a water content of less than 10 ppm, then add 2 kg of 3-chloropropyltriethoxysilane, heat to 40° C., stir and react for 24 hours to obtain silanized silicon dioxide;

[0041] 2) adding the silanized silicon dioxide, bisphenol A epoxy resin and sodium hydride prepared in step 2) into tetrahydrofuran, stirring and mixing evenly, heating to 50-80° C., reacting for 3-5 hours, adding water to quench the reaction after the reaction is completed, then adding dichloromethane for extraction, and distilling the obtained organic layer under reduced pressure to remove the solvent to obtain nano-silicon dioxide modified epoxy resin;

[0042] 3) Add the nano-silica modified epoxy resin and water-based epoxy emulsifier obtained in step 2) into a reactor, disperse them uniformly at high speed at 50-55° C., then drop water thereinto, stir and disperse for 0.5-1 h, and obtain the nano-silica modified water-based epoxy resin.

[0043] 2) adding 0.2 kg of silanized silica obtained in step 1), 1 kg of bisphenol A epoxy resin and 0.1 kg of sodium hydride into 5 kg of tetrahydrofuran, stirring and mixing evenly, heating to 50° C., reacting for 5 h, and after the reaction, adding 3 kg of water to quench the reaction, then adding 3 kg of dichloromethane for extraction, and distilling the obtained organic layer under reduced pressure to remove the solvent to obtain nano-silica modified epoxy resin;

[0044] 3) 1 kg of the nano-silica modified epoxy resin obtained in step 2) and 0.1 kg of water-based epoxy emulsifier were added into the reactor, dispersed evenly at high speed at 50° C., and then 0.7 kg of water was added dropwise thereto, stirred and dispersed for 0.5 h, to obtain the nano-silica modified water-based epoxy resin.

[0045] Preparation of high hardness water-based coating

[0046] Add 5kg of modified water-based alkyd resin, 1kg of pigment titanium dioxide, 0.5kg of filler calcium carbonate, 0.05kg of dispersant sodium polyacrylate and 2kg of water into a high-speed disperser, stir and disperse them evenly at 1500r / min, then add 1kg of nano-silicon dioxide modified water-based epoxy resin, stir and react for 10min, finally add 0.2kg of film-forming aid propylene glycol monoether, 0.01kg of silicone defoamer and 0.01kg of silicone leveling agent, stir and disperse them at 500r / min for 0.5h to obtain a high hardness water-based coating.

[0047] Example 2 Preparation of modified styrene maleic anhydride copolymer

[0048] 0.1 kg of styrene-maleic anhydride copolymer was added to 0.6 kg of cyclohexanone, and after stirring to dissolve, 0.18 kg of polyetheramine ED-900 was added. After stirring and reacting at 97° C. for 3 hours, the solvent was removed by reduced pressure distillation to obtain a modified styrene-maleic anhydride copolymer.

[0049] Preparation of modified waterborne alkyd resin

[0050] 1.4 kg of linoleic acid, 1.1 kg of trimethylolpropane, 0.9 kg of phthalic anhydride, 0.35 kg of modified styrene-maleic anhydride copolymer and 0.15 kg of xylene were added into the reactor, heated to 180°C with stirring, kept warm for 1.5 h, then heated to 200°C for 7 h, and reacted until the acid value reached 13 mgKOH / g. The xylene was removed by vacuum, the temperature was lowered to 180°C, 0.35 kg of trimellitic anhydride was added, and the reaction was continued until the acid value reached 40 mgKOH / g, the temperature was lowered to 70°C, 0.4 kg of triethylamine was added for neutralization reaction for 0.6 h, and finally water was added for high-speed emulsification and dispersion for 30 min, and filtered to obtain a modified waterborne alkyd resin.

[0051] Preparation of waterborne epoxy resin modified by nano-silicon dioxide

[0052] 1) Add 1 kg of nano-silicon dioxide to 6 kg of toluene with a water content of less than 10 ppm, then add 2.5 kg of 3-chloropropyltriethoxysilane, heat to 45° C., stir and react for 20 hours to obtain silanized silicon dioxide;

[0053] 2) adding 0.25 kg of silanized silica obtained in step 1), 1 kg of bisphenol A epoxy resin and 0.12 kg of sodium hydride into 6 kg of tetrahydrofuran, stirring and mixing evenly, heating to 60° C., reacting for 4.5 hours, and after the reaction, adding 3.5 kg of water to quench the reaction, then adding 4 kg of dichloromethane for extraction, and distilling the obtained organic layer under reduced pressure to remove the solvent to obtain nano-silica modified epoxy resin;

[0054] 3) 1 kg of the nano-silica modified epoxy resin obtained in step 2) and 0.12 kg of water-based epoxy emulsifier were added into the reactor, dispersed evenly at high speed at 52° C., and then 0.75 kg of water was added dropwise thereto, stirred and dispersed for 0.6 h, to obtain the nano-silica modified water-based epoxy resin.

[0055] Preparation of high hardness water-based coating

[0056] Add 6kg of modified water-based alkyd resin, 1.1kg of pigment iron red, 0.6kg of filler zinc phosphate, 0.06kg of dispersant fatty alcohol polyoxyethylene ether and 2.2kg of water into a high-speed disperser, stir and disperse them evenly at 1600r / min, then add 1.2kg of nano-silicon dioxide modified water-based epoxy resin, stir and react for 20min, finally add 0.3kg of film-forming aid dipropylene glycol butyl ether, 0.02kg of silicone defoamer and 0.02kg of leveling agent polyacrylic acid, stir and disperse at 600r / min for 0.6h to obtain a high hardness water-based coating.

[0057] Example 3 Preparation of modified styrene maleic anhydride copolymer

[0058] 0.1 kg of styrene-maleic anhydride copolymer was added to 0.7 kg of cyclohexanone, and after stirring to dissolve, 0.2 kg of polyetheramine ED-600 was added. After stirring and reacting at 95° C. for 3.5 hours, the solvent was removed by reduced pressure distillation to obtain a modified styrene-maleic anhydride copolymer.

[0059] Preparation of modified waterborne alkyd resin

[0060] 1.5kg of linoleic acid, 1.2kg of trimethylolpropane, 1kg of phthalic anhydride, 0.4kg of modified styrene-maleic anhydride copolymer and 0.15kg of xylene were added into the reactor, heated to 180°C with stirring, and kept warm for 2h. The temperature was raised to 210°C for 5h. The reaction was continued until the acid value reached 12mgKOH / g. The xylene was removed by vacuum, the temperature was lowered to 180°C, 0.4kg of trimellitic anhydride was added, and the reaction was continued until the acid value reached 40mgKOH / g. The temperature was lowered to 65°C, 0.45kg of triethylamine was added for neutralization for 0.7h, and finally water was added for high-speed emulsification and dispersion for 30min. The mixture was filtered to obtain a modified waterborne alkyd resin.

[0061] Preparation of waterborne epoxy resin modified by nano-silicon dioxide

[0062] 1) Add 1 kg of nano-silicon dioxide to 8 kg of toluene with a water content of less than 10 ppm, then add 3 kg of 3-chloropropyltriethoxysilane, heat to 48° C., stir and react for 18 hours to obtain silanized silicon dioxide;

[0063] 2) adding 0.3 kg of silanized silica obtained in step 1), 1 kg of bisphenol A epoxy resin and 0.15 kg of sodium hydride into 7 kg of tetrahydrofuran, stirring and mixing evenly, heating to 65° C., reacting for 4 h, after the reaction is completed, adding 4 kg of water to quench the reaction, then adding 4 kg of dichloromethane for extraction, and distilling the obtained organic layer under reduced pressure to remove the solvent to obtain nano-silica modified epoxy resin;

[0064] 3) 1 kg of the nano-silica modified epoxy resin obtained in step 2) and 0.15 kg of water-based epoxy emulsifier were added into the reactor, dispersed evenly at high speed at 53° C., and then 0.8 kg of water was added dropwise thereto, stirred and dispersed for 0.7 h, to obtain the nano-silica modified water-based epoxy resin.

[0065] Preparation of high hardness water-based coating

[0066] Add 6.5kg of modified water-based alkyd resin, 1.2kg of pigment yellow iron oxide, 0.7kg of filler calcium carbonate, 0.07kg of dispersant fatty alcohol polyoxyethylene ether and 2.5kg of water into a high-speed disperser, stir and disperse them evenly at 1800r / min, then add 1.3kg of nano-silicon dioxide modified water-based epoxy resin, stir and react for 25min, finally add 0.4kg of film-forming aid dipropylene glycol butyl ether, 0.02kg of defoaming agent polyoxypropylene oxyethylene glycerol ether and 0.03kg of leveling agent polyacrylic acid, stir and disperse at 700r / min for 0.8h to obtain a high hardness water-based coating.

[0067] Example 4 Preparation of modified styrene maleic anhydride copolymer

[0068] 0.1 kg of styrene-maleic anhydride copolymer was added to 0.9 kg of cyclohexanone, and after stirring to dissolve, 0.23 kg of polyetheramine ED-900 was added. After stirring and reacting at 92° C. for 4.5 hours, the solvent was removed by reduced pressure distillation to obtain a modified styrene-maleic anhydride copolymer.

[0069] Preparation of modified waterborne alkyd resin

[0070] 1.8 kg of linoleic acid, 1.3 kg of trimethylolpropane, 1.1 kg of phthalic anhydride, 0.4 kg of modified styrene-maleic anhydride copolymer and 0.18 kg of xylene were added into the reactor, heated to 180°C with stirring, and kept warm for 2.5 hours. The temperature was raised to 220°C for 4 hours. The reaction was continued until the acid value reached 11 mgKOH / g. The xylene was removed by vacuum, the temperature was lowered to 180°C, 0.45 kg of trimellitic anhydride was added, and the reaction was continued until the acid value reached 45 mgKOH / g. The temperature was lowered to 75°C, 0.48 kg of triethylamine was added for neutralization for 0.9 hours, and finally water was added for high-speed emulsification and dispersion for 30 minutes. The mixture was filtered to obtain a modified waterborne alkyd resin.

[0071] Preparation of waterborne epoxy resin modified by nano-silicon dioxide

[0072] 1) Add 1 kg of nano-silicon dioxide to 9 kg of tetrahydrofuran with a water content of less than 10 ppm, then add 3.5 kg of 3-chloropropyltriethoxysilane, heat to 48° C., stir and react for 15 hours to obtain silanized silicon dioxide;

[0073] 2) adding 0.35 kg of silylated silicon dioxide obtained in step 1), 1 kg of bisphenol A epoxy resin and 0.18 kg of sodium hydride into 8 kg of tetrahydrofuran, stirring and mixing evenly, heating to 70° C., reacting for 3.5 hours, and after the reaction, adding 4.5 kg of water to quench the reaction, and then adding 4.5 kg of dichloromethane for extraction, and distilling the obtained organic layer under reduced pressure to remove the solvent to obtain nano-silicon dioxide modified epoxy resin;

[0074] 3) 1 kg of the nano-silica modified epoxy resin obtained in step 2) and 0.18 kg of water-based epoxy emulsifier were added into the reactor, dispersed evenly at high speed at 54° C., and then 0.85 kg of water was added dropwise thereto, stirred and dispersed for 0.8 h, to obtain the nano-silica modified water-based epoxy resin.

[0075] Preparation of high hardness water-based coating

[0076] Add 7.5kg of modified water-based alkyd resin, 1.3kg of pigment iron blue, 0.75kg of filler talcum powder, 0.07kg of dispersant sodium polyacrylate and 3kg of water into a high-speed disperser, stir and disperse them evenly at 1900r / min, then add 1.4kg of nano-silicon dioxide modified water-based epoxy resin, stir and react for 28min, finally add 0.6kg of film-forming aid diethylene glycol monobutyl ether, 0.02kg of silicone defoamer and 0.04kg of leveling agent polyacrylic acid, stir and disperse at 750r / min for 0.9h to obtain a high hardness water-based coating.

[0077] Example 5 Preparation of modified styrene maleic anhydride copolymer

[0078] 0.1 kg of styrene-maleic anhydride copolymer was added to 1 kg of cyclohexanone, and after stirring to dissolve, 0.25 kg of polyetheramine ED-600 was added. After stirring and reacting at 100° C. for 2 hours, the solvent was removed by reduced pressure distillation to obtain a modified styrene-maleic anhydride copolymer.

[0079] Preparation of modified waterborne alkyd resin

[0080] 2kg of linoleic acid, 1.5kg of trimethylolpropane, 1.2kg of phthalic anhydride, 0.5kg of modified styrene-maleic anhydride copolymer and 0.2kg of xylene were added into the reactor, heated to 180°C with stirring, and kept warm for reaction for 3h, then heated to 230°C for reaction for 3h, and reacted until the acid value reached 10mgKOH / g, vacuumed to remove the xylene, cooled to 180°C, added with 0.5kg of trimellitic anhydride, and kept warm for reaction until the acid value reached 50mgKOH / g, cooled to 80°C, added with 0.5kg of triethylamine for neutralization reaction for 1h, and finally added with water for high-speed emulsification dispersion for 30min, filtered to obtain a modified waterborne alkyd resin.

[0081] Preparation of waterborne epoxy resin modified by nano-silicon dioxide

[0082] 1) Add 1 kg of nano-silicon dioxide to 10 kg of tetrahydrofuran with a water content of less than 10 ppm, then add 4 kg of 3-chloropropyltriethoxysilane, heat to 50° C., stir and react for 10 hours to obtain silanized silicon dioxide;

[0083] 2) adding 0.4 kg of silanized silica obtained in step 1), 1 kg of bisphenol A epoxy resin and 0.2 kg of sodium hydride into 10 kg of tetrahydrofuran, stirring and mixing evenly, heating to 80° C., reacting for 3 h, and after the reaction, adding 5 kg of water to quench the reaction, then adding 5 kg of dichloromethane for extraction, and distilling the obtained organic layer under reduced pressure to remove the solvent to obtain nano-silica modified epoxy resin;

[0084] 3) 1 kg of the nano-silica modified epoxy resin obtained in step 2) and 0.2 kg of water-based epoxy emulsifier were added into the reactor, dispersed evenly at high speed at 55° C., and then 0.9 kg of water was added dropwise thereto, stirred and dispersed for 1 hour to obtain the nano-silica modified water-based epoxy resin.

[0085] Preparation of high hardness water-based coating

[0086] Add 8kg of modified water-based alkyd resin, 1.5kg of pigment titanium dioxide, 0.8kg of filler calcium carbonate, 0.08kg of dispersant sodium polyacrylate and 3.5kg of water into a high-speed disperser, stir and disperse them evenly at 2000r / min, then add 1.5kg of nano-silicon dioxide modified water-based epoxy resin, stir and react for 30min, finally add 0.8kg of film-forming aid diethylene glycol monobutyl ether, 0.03kg of silicone defoamer and 0.05kg of silicone leveling agent, stir and disperse them at 800r / min for 1h to obtain a high hardness water-based coating.

[0087] Example 6 Preparation of modified styrene maleic anhydride copolymer

[0088] 0.1 kg of styrene-maleic anhydride copolymer was added to 0.8 kg of cyclohexanone, and after stirring to dissolve, 0.2 kg of polyetheramine ED-600 was added. After stirring and reacting at 100° C. for 5 hours, the solvent was removed by reduced pressure distillation to obtain a modified styrene-maleic anhydride copolymer.

[0089] Preparation of modified waterborne alkyd resin

[0090] 1.2kg of linoleic acid, 1.5kg of trimethylolpropane, 0.8kg of phthalic anhydride, 0.5kg of modified styrene-maleic anhydride copolymer and 0.2kg of xylene were added into the reactor, heated to 180°C with stirring, and kept warm for reaction for 3h, then heated to 230°C for reaction for 8h, and reacted until the acid value reached 15mgKOH / g, vacuumed to remove the xylene, cooled to 180°C, added with 0.5kg of trimellitic anhydride, and kept warm for reaction until the acid value reached 45mgKOH / g, cooled to 60°C, added with 0.5kg of triethylamine for neutralization reaction for 1h, and finally added with water for high-speed emulsification dispersion for 30min, filtered to obtain a modified waterborne alkyd resin.

[0091] Preparation of waterborne epoxy resin modified by nano-silicon dioxide

[0092] 1) Add 1 kg of nano-silicon dioxide to 8 kg of toluene with a water content of less than 10 ppm, then add 3 kg of 3-chloropropyltriethoxysilane, heat to 50° C., stir and react for 24 hours to obtain silanized silicon dioxide;

[0093] 2) adding 0.3 kg of silanized silica obtained in step 1), 1 kg of bisphenol A epoxy resin and 0.15 kg of sodium hydride into 7 kg of tetrahydrofuran, stirring and mixing evenly, heating to 55° C., reacting for 5 h, and after the reaction, adding 3 kg of water to quench the reaction, then adding 5 kg of dichloromethane for extraction, and distilling the obtained organic layer under reduced pressure to remove the solvent to obtain nano-silica modified epoxy resin;

[0094] 3) 1 kg of the nano-silica modified epoxy resin obtained in step 2) and 0.15 kg of water-based epoxy emulsifier were added into the reactor, dispersed evenly at high speed at 55° C., and then 0.8 kg of water was added dropwise thereto, stirred and dispersed for 1 hour to obtain the nano-silica modified water-based epoxy resin.

[0095] Preparation of high hardness water-based coating

[0096] Add 5kg of modified water-based alkyd resin, 1.2kg of pigment yellow iron oxide, 0.8kg of filler calcium carbonate, 0.08kg of dispersant fatty alcohol polyoxyethylene ether and 3.5kg of water into a high-speed disperser, stir and disperse them evenly at 2000r / min, then add 1.5kg of nano-silicon dioxide modified water-based epoxy resin, stir and react for 20min, finally add 0.5kg of film-forming aid dipropylene glycol butyl ether, 0.02kg of defoaming agent polyoxypropylene ethylene glycerol ether and 0.05kg of silicone leveling agent, stir and disperse them at 800r / min for 0.5h to obtain a high hardness water-based coating.

[0097] The high hardness water-based coatings prepared in Examples 1 to 6 were sprayed onto the test plates respectively, and tested according to the method in HG / T4847-2015. The test results are shown in Table 1.

[0098] Table 1 Performance parameter results of coatings

[0099]

[0100] It can be seen from the results in Table 1 that the high-hardness water-based coating prepared by the present invention has the characteristics of high hardness, good toughness, good water resistance, high adhesion and high stability, and has broad application prospects.

[0101] Although the above describes the specific implementation methods of the present invention, it does not limit the scope of protection of the present invention. Based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.

Claims

1. A high hardness water-based paint, characterized in that: The invention is composed of the following raw materials in parts by weight: 50-80 parts of modified waterborne alkyd resin, 10-15 parts of nano-silicon dioxide modified waterborne epoxy resin, 2-8 parts of film-forming aid, 10-15 parts of pigment, 5-8 parts of filler, 0.5-0.8 parts of dispersant, 0.1-0.3 parts of defoamer, 0.1-0.5 parts of leveling agent and 20-35 parts of water; The modified waterborne alkyd resin is prepared by modifying an alkyd resin with a modified styrene-maleic anhydride copolymer, wherein a polyetheramine is grafted onto the modified styrene-maleic anhydride copolymer; The modified styrene-maleic anhydride copolymer is prepared according to the following method: Add styrene-maleic anhydride copolymer to cyclohexanone, stir to dissolve, then add polyetheramine, stir to react at 90-100° C. for 2-5 hours, and then remove the solvent by distillation under reduced pressure to obtain a modified styrene-maleic anhydride copolymer.

2. The high hardness water-based paint according to claim 1, characterized in that: The mass ratio of the styrene-maleic anhydride copolymer, cyclohexanone and polyetheramine is 1:5-10:1.5-2.

5.

3. The high hardness water-based paint according to claim 1, characterized in that: The polyetheramine is polyetheramine ED-600 or polyetheramine ED-900.

4. The high hardness water-based paint according to claim 1, characterized in that: The film-forming aid is propylene glycol monoether, dipropylene glycol butyl ether or diethylene glycol monobutyl ether; the pigment is titanium white, iron oxide yellow, iron red, iron blue or carbon black; the filler is calcium carbonate, talcum powder or zinc phosphate; the dispersant is sodium polyacrylate or fatty alcohol polyoxyethylene ether; the defoamer is an organosilicon defoamer or polyoxypropylene ethylene glycerol ether; and the leveling agent is polyacrylic acid or an organosilicon leveling agent.

5. The high hardness water-based paint according to claim 1, characterized in that: The preparation method of the modified waterborne alkyd resin comprises the following steps: In parts by weight, 12 to 20 parts of linoleic acid, 10 to 15 parts of trimethylolpropane, 8 to 12 parts of phthalic anhydride, 3 to 5 parts of modified styrene-maleic anhydride copolymer and 1 to 2 parts of xylene are added to a reactor, stirred and heated to 180°C, kept warm for reaction for 1 to 3 hours, heated to 190 to 230°C for reaction for 3 to 8 hours, reacted until the acid value reached 10 to 15 mgKOH / g, vacuumed to remove the xylene, cooled to 180°C, added 3 to 5 parts of trimellitic anhydride, continued to keep warm for reaction until the acid value reached 35 to 50 mgKOH / g, cooled to 60 to 80°C, added 4 to 5 parts of triethylamine for neutralization reaction for 0.5 to 1 hour, finally added water for high-speed emulsification dispersion for 30 minutes, filtered, and obtained a modified waterborne alkyd resin.

6. The high hardness water-based paint according to claim 1, characterized in that: The nano-silicon dioxide modified waterborne epoxy resin is prepared according to the following method: 1) Add nano-silicon dioxide to an organic solvent with a water content of less than 10 ppm, then add 3-chloropropyltriethoxysilane, heat to 40-50° C., and stir to react for 10-24 hours to obtain silanized silicon dioxide; 2) adding the silanized silicon dioxide, bisphenol A epoxy resin and sodium hydride prepared in step 1) into tetrahydrofuran, stirring and mixing evenly, heating to 50-80° C., reacting for 3-5 hours, adding water to quench the reaction after the reaction is completed, then adding dichloromethane for extraction, and distilling the obtained organic layer under reduced pressure to remove the solvent to obtain nano-silicon dioxide modified epoxy resin; 3) Add the nano-silica modified epoxy resin and water-based epoxy emulsifier obtained in step 2) into a reactor, disperse them uniformly at high speed at 50-55° C., then drop water thereinto, stir and disperse for 0.5-1 h, and obtain the nano-silica modified water-based epoxy resin.

7. The high hardness water-based paint according to claim 6, characterized in that: The organic solvent in step 1) is tetrahydrofuran or toluene; the mass ratio of the nano-silica, the organic solvent and 3-chloropropyltriethoxysilane in step 1) is 1:5-10:2-4.

8. The high hardness water-based paint according to claim 6, characterized in that: The mass ratio of the silanized silicon dioxide, bisphenol A epoxy resin, sodium hydride, tetrahydrofuran, water and dichloromethane in step 2) is 0.2-0.4:1:0.1-0.2:5-10:3-5:3-5.

9. The high hardness water-based paint according to claim 6, characterized in that: The mass ratio of the nano-silica modified epoxy resin, the water-based epoxy emulsifier and water in step 3) is 1:0.1-0.2:0.7-0.

9.

10. The method for preparing the high hardness water-based coating according to claim 1, characterized in that: The following steps are involved: In parts by weight, 50-80 parts of modified water-based alkyd resin, 10-15 parts of pigment, 5-8 parts of filler, 0.5-0.8 parts of dispersant and 20-35 parts of water are added into a high-speed disperser, and the mixture is stirred and dispersed evenly at 1500-2000 r / min. Then 10-15 parts of nano-silicon dioxide modified water-based epoxy resin are added thereto, and the mixture is stirred and reacted for 10-30 minutes. Finally, 2-8 parts of film-forming aid, 0.1-0.3 parts of defoaming agent and 0.1-0.5 parts of leveling agent are added, and the mixture is stirred and dispersed at 500-800 r / min for 0.5-1 hour to obtain a high-hardness water-based coating.

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