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CN-121991578-A - High-weather-resistance fluoride-free sand grain powder coating and preparation method thereof

CN121991578ACN 121991578 ACN121991578 ACN 121991578ACN-121991578-A

Abstract

The invention relates to the technical field of powder coatings, in particular to a high weather-resistant fluoride-free sand grain powder coating and a preparation method thereof. A method for preparing the high weather-proof fluoride-free sand grain powder coating comprises the steps of preparing a flame retardant additive, preparing an alumina composite material, preparing modified cellulose nanocrystalline and preparing the powder coating. According to the invention, quaternization reaction is carried out on alkali lignin and 3-chloro-2-hydroxypropyl trimethyl ammonium chloride to prepare quaternized alkali lignin, then silane coupling agent is used for surface modification of modified nano alumina, finally quaternized alkali lignin and modified nano alumina are fully contacted and compounded to form a core-shell type alumina composite material with modified nano alumina as a core and quaternized alkali lignin as a shell, and after the core-shell type alumina composite material is added into powder coating, the dispersibility of nano alumina in the powder coating can be effectively improved, the ultraviolet ageing resistance of the powder coating can be effectively improved, and the weather resistance of the powder coating can be further improved.

Inventors

  • XU YI
  • CHEN GUOXIANG
  • Ying Pinfeng
  • Chen Miaoxi
  • TIAN GUI
  • FU HUIJUAN

Assignees

  • 金华市大友谊塑粉科技有限公司

Dates

Publication Date
20260508
Application Date
20260211

Claims (10)

  1. 1. The preparation method of the high weather-proof fluoride-free sand grain powder coating is characterized by comprising the following steps of: S1, preparing a flame retardant additive Mixing itaconic acid and diethyl bis (2-hydroxyethyl) amino methyl phosphonate, adding hydroquinone and tetrabutyl titanate for reaction to obtain a flame retardant additive; S2, preparing aluminum oxide composite material Firstly, preparing quaternized alkali lignin by taking alkali lignin and 3-chloro-2-hydroxypropyl trimethyl ammonium chloride as raw materials, then modifying nano alumina by using a silane coupling agent, and finally dispersing the quaternized alkali lignin and the modified alumina in an ethanol solution for reaction to obtain an alumina composite material; S3, preparing modified cellulose nanocrystalline Preparing a eugenol modifier by taking eugenol and trimethoxy silane as raw materials, and then mixing the eugenol modifier with cellulose nanocrystals for reaction to obtain modified cellulose nanocrystals; s4, preparing the powder coating S4.1, heating the carboxyl polyester prepolymer to 230-240 ℃ for pre-polycondensation for 40-50min, adding the dried hydroxyl-terminated polydimethylsiloxane, carrying out heat preservation and stirring reaction for 2-3h, regulating the temperature to 220-230 ℃, adding benzoic acid, continuing heat preservation and stirring for 30-40min, cooling, solidifying, crushing and sieving with a 60-mesh sieve to obtain the organosilicon modified polyester; S4.2, dry-mixing the organosilicon modified polyester, the curing agent, the flame retardant additive, the aluminum oxide composite material, the modified cellulose nanocrystalline, the filler, the pigment, the fluorine-free sand grain agent, the degasifying agent and the antioxidant, then adopting a double-screw extruder to melt and extrude at 100-120 ℃, and then cooling, pressing into tablets, crushing and sieving with a 200-mesh sieve to obtain the powder coating.
  2. 2. The method for preparing the high weather-resistant fluoride-free sand grain powder coating according to claim 1, wherein the step S1 comprises the following steps: S1.1, respectively drying itaconic acid and diethyl bis (2-hydroxyethyl) amino methyl phosphonate in vacuum at 60-80 ℃ for 2-4 hours, and dehydrating to obtain dried itaconic acid and diethyl bis (2-hydroxyethyl) amino methyl phosphonate; S1.2, mixing dry itaconic acid and dry diethyl bis (2-hydroxyethyl) amino methyl phosphonate according to the formula 1 (2.3-2.4), adding hydroquinone and tetrabutyl titanate with equal mass, heating and stirring for reacting for 2-3h at 150-160 ℃ under the protection of nitrogen, heating to 170 ℃, carrying out vacuum heat preservation and polycondensation for 40-50min, continuously heating to 180 ℃, carrying out heat preservation and polycondensation for 1-2h, and naturally cooling to room temperature to obtain the flame retardant additive, wherein the adding amount of hydroquinone is 0.16-0.18% of the mass of the dry itaconic acid.
  3. 3. The method for preparing the high weather-resistant fluoride-free sand grain powder coating according to claim 2, wherein the step of S2 comprises the following steps: s2.1, adding alkali lignin and sodium hydroxide into deionized water according to (16-18) g (80-90) mL, heating and stirring for 1-2 hours at 40-50 ℃ to obtain alkali lignin solution, adding 3-chloro-2-hydroxypropyl trimethyl ammonium chloride aqueous solution with the mass fraction of 70%, heating to 65-75 ℃, carrying out heat preservation and reflux reaction for 4-5 hours, cooling, adding glacial acetic acid to adjust the pH to 6.5-7, and carrying out rotary steaming and vacuum drying to obtain quaternized alkali lignin; s2.2, adding nano alumina into absolute ethyl alcohol according to 1g (10-12) mL, performing ultrasonic dispersion for 30-40min, adding a silane coupling agent KH-570, heating, stirring and refluxing for 2.5-3.5h at 60-70 ℃, cooling, and performing suction filtration, washing and vacuum drying to obtain modified nano alumina, wherein the adding amount of the silane coupling agent KH-570 is 5% of the mass of the nano alumina; s2.3, adding the quaternized alkali lignin and the modified nano alumina into an ethanol water solution with the volume fraction of 50% according to (13-15) mL (2.3-2.5), ultrasonically dispersing for 40-50min, stirring and refluxing for 2-3h at 70-80 ℃, and then carrying out vacuum concentration at 80-90 ℃, vacuum drying, grinding and sieving by a 100-mesh sieve to obtain the alumina composite material.
  4. 4. The method for preparing the high weather-resistant fluoride-free sand streak powder coating according to claim 3, wherein the step S3 comprises the following steps: S3.1, preheating eugenol to 50-55 ℃ under the protection of nitrogen, adding chloroplatinic acid-isopropanol catalyst solution, fully stirring and mixing, adding trimethoxy silane, heating and stirring at 70-80 ℃ for reaction for 3-3.5h, cooling, and carrying out reduced pressure distillation and rotary evaporation to obtain a eugenol-based modifier, wherein the mass ratio of trimethoxy silane to eugenol is 1 (1.3-1.4); s3.2, according to the volume ratio (8.5-9.5), 1, stirring and mixing absolute ethyl alcohol and deionized water, and then adding glacial acetic acid to adjust the pH value to 4-5, thus obtaining a mixed solution; S3.3, adding cellulose nanocrystalline into the mixed solution according to 1g (50-60) mL, performing ultrasonic dispersion for 30-40min to obtain cellulose nanocrystalline dispersion liquid, adding the eugenol-based modifier into the mixed solution according to 1g (8-10) mL, and performing stirring hydrolysis for 30-40min to obtain modifier hydrolysate; S3.4, adding the modifier hydrolysate into the cellulose nanocrystalline dispersion liquid, heating and stirring at 55-60 ℃ for reaction for 3-4 hours, cooling, centrifugally collecting precipitate, washing, vacuum drying, grinding and sieving with a 80-mesh sieve to obtain modified cellulose nanocrystalline, wherein the mass ratio of the eugenol-based modifier to the cellulose nanocrystalline is 1 (8-10).
  5. 5. The method for preparing the high weather-resistant fluoride-free sand streak powder coating according to claim 3, wherein the mass ratio of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride to alkali lignin in the 3-chloro-2-hydroxypropyl trimethyl ammonium chloride aqueous solution is (0.7-0.8): 1.
  6. 6. The method for preparing the highly weather-resistant fluoride-free sand streak powder coating material as claimed in claim 4, wherein the chloroplatinic acid-isopropanol catalyst solution is prepared by mixing chloroplatinic acid hexahydrate and anhydrous isopropanol according to a ratio of 2mg to 1ml, and the amount of the chloroplatinic acid hexahydrate is 0.004% of the mass of eugenol.
  7. 7. The method for preparing the high weather-resistant fluoride-free sand streak powder coating according to claim 1, wherein the mass ratio of terephthalic acid, isophthalic acid, neopentyl glycol and ethylene glycol is (9.5-10.5): (4.1-4.3): (8.1-8.3): 1, and the addition amount of tetrabutyl titanate is 0.1% of the total mass of terephthalic acid, isophthalic acid, neopentyl glycol and ethylene glycol.
  8. 8. The preparation method of the high weather-resistant fluorine-free sand streak powder coating according to claim 1, wherein the addition amount of the hydroxyl-terminated polydimethylsiloxane is 5-6% of the mass of the carboxyl polyester prepolymer, and the addition amount of the benzoic acid is 4-8% of the mass of the hydroxyl-terminated polydimethylsiloxane.
  9. 9. The preparation method of the high weather-resistant fluoride-free sand grain powder coating according to claim 1 is characterized in that the powder coating comprises, by mass, 3-4% of a curing agent, 8-10% of a flame retardant additive, 10-12% of an alumina composite material, 1-3% of modified cellulose nanocrystals, 18-22% of a filler, 2-6% of a pigment, 0.5-1.5% of a fluoride-free sand grain agent, 0.4-1% of a degassing agent and 0.3-0.5% of an antioxidant, and the balance of an organosilicon modified polyester, wherein the curing agent is triglycidyl isocyanurate, the filler is any one of barium sulfate, talcum powder, calcium carbonate or mica powder, the pigment is any one of titanium dioxide or carbon black, the fluoride-free sand grain agent is Ceridust 8170M, the degassing agent is any one of benzoin 1010 or antioxidant 168.
  10. 10. A highly weatherable fluorine-free sand grain powder coating, characterized in that it is prepared by a method for preparing a highly weatherable fluorine-free sand grain powder coating according to any one of claims 1 to 9.

Description

High-weather-resistance fluoride-free sand grain powder coating and preparation method thereof Technical Field The invention relates to the technical field of powder coatings, in particular to a high weather-resistant fluoride-free sand grain powder coating and a preparation method thereof. Background The powder coating is a solvent-free environment-friendly coating which is composed of resin, curing agent, pigment, filler, auxiliary agent and the like, and is widely applied to the outdoor fields of building aluminum profiles, outdoor furniture, new energy charging pile shells, photovoltaic brackets and the like due to the characteristics of no organic volatile matters, environment protection, high efficiency, excellent coating performance and the like. The sand grain powder coating can endow the coating with fine concave-convex texture and has skid resistance and attractive appearance, and the traditional sand grain powder coating mostly adopts fluorine-containing sand grain agents to realize sand grain effect, but the perfluoro compound contained in the sand grain powder coating is difficult to degrade and does not accord with the restrictions of international environmental protection regulations such as European Union REACH, american EPA and the like, so that no fluorination becomes the development core trend of the sand grain powder coating. At present, the conventional fluoride-free sand grain powder coating adopts polyolefin wax, amide and other fluoride-free sand grain agents to replace fluorine-containing components, but generally has the problem of insufficient weather resistance, and the phenomena of low light retention rate, fuzzy sand grain loss, coating chalking and color change and the like are easy to occur after ultraviolet ageing. The nano aluminum oxide has better scattering and ultraviolet absorption effects, can be used for improving the ultraviolet resistance of the powder coating, but has extremely small particle diameter, huge specific surface area and extremely high surface energy, has poor compatibility with a resin matrix, and is easy to agglomerate in the resin matrix in the process of melt extrusion, so that the ultraviolet aging resistance of the powder coating is improved. In addition, the common epoxy, polyester and other resins used in powder coating are organic polymer materials, belong to inflammable or flammable substances, and generally require adding flame retardants to ensure that the powder coating has flame retardant property, however, the conventional flame retardants such as aluminum hydroxide have large chemical polarity difference with a resin matrix, and the high temperature during processing can ensure that the flame retardants have good dispersibility in molten resin, but after cooling and solidification, flame retardant molecules gradually migrate to the surface from the inside of the resin, part of the flame retardants have strong hygroscopicity, moisture in the environment can aggravate migration and surface precipitation, so that the powder coating is difficult to realize long-term flame retardance, and the resin such as polyester contains a large number of chemical bonds such as ester groups, carbon-carbon single bonds and the like in the molecular chain, so that the bond energy is relatively low, the thermal movement and slippage of the molecular chain are easy to occur in a high temperature environment, and even the thermal decomposition, hydrolysis and thermal oxidative degradation of the ester groups can be initiated, so that the resin structure is damaged. Therefore, a high weather-proof fluorine-free sand grain powder coating with ultraviolet aging resistance, flame retardance and high temperature resistance and a preparation method thereof are needed to prolong the service life of the powder coating. Disclosure of Invention Aiming at the defects existing in the prior art, the invention aims to provide the high weather-resistant fluoride-free sand grain powder coating and a preparation method thereof. The invention provides a preparation method of a high weather-proof fluoride sand streak-free powder coating, which comprises the following steps: S1, preparing a flame retardant additive Mixing itaconic acid and diethyl bis (2-hydroxyethyl) amino methyl phosphonate, adding hydroquinone and tetrabutyl titanate for reaction to obtain a flame retardant additive; S2, preparing aluminum oxide composite material Firstly, preparing quaternized alkali lignin by taking alkali lignin and 3-chloro-2-hydroxypropyl trimethyl ammonium chloride as raw materials, then modifying nano alumina by using a silane coupling agent, and finally dispersing the quaternized alkali lignin and the modified alumina in an ethanol solution for reaction to obtain an alumina composite material; S3, preparing modified cellulose nanocrystalline Preparing a eugenol modifier by taking eugenol and trimethoxy silane as raw materials, and then mixing the eugenol modifier with cellulose nanocry