A method for preparing a fluoride-containing aqueous polyurethane coating

Abstract

The present invention provides a method for preparing a fluorine-containing waterborne polyurethane coating, which is characterized in that dihydroxy-containing dimethylaminoethyl methacrylate is first prepared by ultraviolet light initiation technology, and then a dihydroxy fluorine-containing ion monomer is prepared by alkylation reaction and ion exchange method; the monomer is introduced into a polyurethane matrix in the form of a chain extender to obtain a fluorine-containing waterborne polyurethane coating material. The fluorine ions in the polyurethane coating material prepared by the present invention can be released into the oral environment through ion exchange and supplemented from external fluorine-containing substances, and the quaternary ammonium salt cations contained therein also have excellent antibacterial properties; at the same time, the preparation process is simple, repeatable, and universal, and the coating can be quickly cured. This patent introduces the prepared fluorine-containing ion monomer into polyurethane at the molecular level through ingenious design, and the prepared waterborne polyurethane coating can repeatedly charge and discharge fluorine ions to achieve a long-term and effective effect of preventing tooth decay.

Description

Technical Field

[0001] The invention relates to the research field of surface coating materials required for (dental caries, etc.), and in particular to a preparation method of a fluorine-containing waterborne polyurethane coating. Background Art

[0002] Dental caries, commonly known as tooth decay or tooth decay, is an oral disease in which the tooth tissue is corroded, gradually destroyed and disintegrated, forming a cavity. It is a common bacterial infection disease in the oral department. Children are a high-risk group for dental caries. The resulting tooth damage problem is clinically recommended to be repaired and treated as soon as possible; if dental caries are not repaired in time, it will affect the eruption of permanent teeth in children, causing greater oral hygiene problems. Dental caries is the most common disease after colds and is one of the main causes of tooth loss. Dental caries is caused by bacteria, food residues, and saliva in the mouth that form dental plaque (a sticky transparent film) and adhere to the surface of the teeth. The cause of tooth decay is caused by bacteria. There are many types of bacteria that cause caries, the most important of which are certain mutans streptococci and lactobacilli. These bacteria are mixed with mucin and food residues in saliva and firmly adhere to the surface of the teeth and in the pits and fissures. This adhesive is called dental plaque or plaque. A large number of bacteria in the plaque produce acid, causing the tooth enamel surface under the plaque to decalcify and dissolve. In the process of dental caries formation, diet is an important factor for bacteria. Food contains a lot of carbohydrates and sugars, which not only provide energy for the life and activity of bacteria in plaque, but also produce organic acids through bacterial metabolism. The acids are retained on the tooth surface and in the pits and fissures for a long time, causing enamel demineralization and destruction. Then some bacteria dissolve proteins to form caries. There are many caries-causing sugars, the most important of which is sucrose.

[0003] Fluoride is an element that can effectively reduce and prevent the occurrence of dental caries. Its anti-caries mechanism is complex. The currently recognized view is that fluoride can reduce the solubility of the enamel on the surface of the teeth and promote the remineralization of the enamel. First, under the same acidity conditions, if fluoride is present, the solubility of the teeth is reduced and it is not easy to decay. Even if the teeth have a small decay, as long as they are exposed to fluoride, the decay can be reversed to a certain extent. Secondly, fluoride can not only inhibit the growth of cariogenic bacteria in the mouth and inhibit the acid production of bacteria, but also inhibit the entire cariogenic bacteria from decomposing food residues to produce acid, and the acid dissolves the minerals in the teeth to form caries. Finally, fluoride can also affect the morphological structure of teeth. Intake of an appropriate amount of fluoride during tooth development can make the cusps round and blunt and the grooves shallow; this morphological change can make the teeth easy to self-clean and enhance resistance. Since the process of dental caries can occur at any time, and fluoride can only play a role in preventing dental caries when it is often present in the mouth, so fluoride coating is actually to apply a protective film to children's teeth, which can effectively prevent the occurrence of dental caries. The "fluorine" in various fluoride toothpastes used in our daily lives is inorganic fluoride. It can be seen that the fluorine element has been widely used in various oral materials.

[0004] Materials commonly used in the oral cavity are mostly required to meet the following characteristics: 1. Good biocompatibility and low toxicity; 2. Appropriate mechanical strength; 3. Excellent antibacterial properties. At present, the main anti-caries fluoride materials are mostly resin composite materials filled with inorganic fillers, which physically embed a certain amount of inorganic fluoride. The main method of use is to etch the enamel with acid, then apply a binder, and then fill the resin and solidify it. Sometimes a container is required to fix the resin. The fluoride ions are released through the concentration gradient in the oral environment, and generally there is an excessive release phenomenon in the first few hours. Therefore, it has good mechanical strength and appearance performance, and can also release fluoride ions for a certain period of time. With the increasing application of tooth filling materials and removable denture base materials, in order to achieve the purpose of preventing abutment tooth caries, seeking a safer and simpler method of local fluoride, developing a safer and more ideal fluoride-containing material, and ensuring that the fluoride added to the material can not only continuously and effectively play the role of anti-caries, but also do not reduce the physical and chemical properties of the material, will be the current research direction.

[0005] The Chinese patent document with the publication number CN101721316A discloses a nano-fluorine-containing resin dental material and a preparation method thereof. The nano-fluorine-containing resin dental material and the preparation method thereof belong to the technical field of light-cured resin dental materials and powder dispersion methods. The resin dental material is composed of methacrylate monomers, initiators and inorganic fillers. The inorganic fillers contain fluorine-containing glass powder, nano-silicon powder, dyes, strontium glass or / and barium glass; and may also contain nano YbF3 and Bi2O3. The preparation involves silanization treatment of fluorine-containing glass powder and nano-silicon powder, and ultrasonic dispersion technology of nano-silicon powder in an organic medium. The invented resin dental material has biological activity, can resist tooth caries, and has ideal effects in radiation blocking performance, transparency, tensile strength, wear resistance, density, rheology and other properties. In particular, the combination of fluorine-containing glass powder and preferred methacrylate monomers has the best effect on fluorine release and mechanical properties. The Chinese patent document with the publication number CN101703451A discloses a fluoride-containing dental restorative material based on a drug sustained release mechanism. This invention relates to a fluoride-containing dental restorative material based on a drug sustained release mechanism, and belongs to the field of dental preparations. The existing simple fluoride-doped composite resin dental filling materials have the problems of too fast fluoride release, poor interface compatibility, and no rigid support for the dental filling. This invention aims to solve the above problems by selecting fluorine-loaded zirconium dioxide nanotubes with both the functions of sustained fluoride release to resist secondary dental caries and structural reinforcement as nano inorganic powders. The weight percentage of each component of the material is as follows: 20% to 85% of nano inorganic powder surface modified by a silane coupling agent; 8% to 70% of a resin monomer such as bisphenol A glycidyl methacrylate; 5% to 25% of a diluent such as triethylene glycol dimethacrylate; 0.25% to 2% of a photoinitiator such as camphorquinone; and 0.5% to 3% of a co-initiator such as dimethylaminoethyl methacrylate. In addition to directly adding fluorine-containing inorganic salts to polymer resins, there is another way to introduce fluorine, that is, to introduce fluorine-containing substances into materials in the form of monomers, so as to achieve a long-term anti-caries effect. The Chinese patent document with publication number CN106957266A discloses a dental resin monomer containing fluorine ions, and its preparation method and application. This invention provides a dental resin monomer containing fluorine ions. The dental resin prepared with it as a fluorine-containing monomer can achieve long-term sustained release and repeated charging and discharging of fluorine ions, effectively prevent the occurrence of caries, and has good antibacterial properties. The Chinese patent document with publication number CN101146507 discloses a dental fluorine ion releasing composition.The present invention provides a dental fluoride ion-releasing composition comprising an inorganic powder, a fluoride ion-releasing substance, a polymerizable monomer, and a polymerization initiator, wherein the inorganic powder is composed of composite particles having a layer composed of polysiloxane formed on the surface of matrix particles composed of an inorganic substance, and the fluoride ion-releasing substance is at least one fluoride ion-releasing substance selected from the group consisting of ammonium fluoride, ammonium hydrogen fluoride, a metal fluoride, a polymer having a vinyl monomer having an acyl fluoride group as a constituent unit, and a fluorine-containing phosphazene monomer. The dental fluoride ion-releasing composition of the present invention can impart high caries resistance to tooth substance for a long period of time by slowly releasing fluoride ions, and is therefore particularly useful as a dental material such as a dental adhesive, a dental filling material, a dental framework-building resin, a pit and fissure sealing material, a dental coating material (tooth restoration), and a dental cement.

[0006] Waterborne polyurethane is a new type of polyurethane system that uses water instead of organic solvents as a dispersion medium. It is also called water-dispersible polyurethane, water-based polyurethane or water-based polyurethane. Waterborne polyurethane uses water as a solvent and has the advantages of being pollution-free, safe and reliable, having excellent mechanical properties, good compatibility, and being easy to modify. It is also used in oral materials.

[0007] Based on this, the present invention discloses a method for preparing a waterborne polyurethane coating containing fluorine ions, wherein a dihydroxy fluorine ion monomer small molecule chain extender is prepared by ultraviolet light irradiation initiation technology, and then introduced into a polyurethane matrix by addition polymerization reaction, thereby giving the polyurethane coating the function of repeatedly charging and discharging fluorine ions, so as to effectively prevent the occurrence of caries. This method has not been reported in literature or patents. The waterborne polyurethane coating can be used for surface modification of dental resin-based restorations and surface modification of dental implants, giving them anti-caries functions. Summary of the invention

[0008] The present invention provides a method for preparing a fluorine-containing waterborne polyurethane coating, which is characterized in that the preparation method comprises firstly obtaining a polyurethane prepolymer by reacting a polyol with a diisocyanate, then adding a dihydroxy fluorine-containing ion monomer as a molecular chain extender, reacting under the action of a catalyst, then adding a hydrophilic chain extender to carry out a molecular chain extension reaction, and finally obtaining the coating by neutralization reaction and water-based emulsification operation. The specific steps are as follows:

[0009] (1) Add diisocyanate and hydroxyl group of polyol into the reactor in a molar ratio of (4-10):1, add an appropriate amount of solvent (to ensure that the solid content of the reaction system is 30%), the temperature is 60-90 °C, the stirring speed is 500-3000 rpm, and the stirring reaction is carried out for 0.5-2 h to obtain a polyurethane prepolymer;

[0010] (2) Adding dihydroxy fluorine-containing ion monomer as a molecular chain extender into the reactor, the molar ratio of dihydroxy fluorine-containing ion monomer to diisocyanate is (0.05-0.7):1, the temperature is 60-90 °C, the stirring speed is 200-2000 rpm, and the reaction is carried out under catalyst conditions for 1-5 hours;

[0011] (3) Add dimethylolpropionic acid and diisocyanate into the reactor at a molar ratio of (0.02-0.7):1, at a temperature of 60-90°C, a stirring speed of 200-2000 rpm, and react for 1-4 hours under catalyst conditions;

[0012] (4) adding a neutralizing agent, triethylamine or triethanolamine, to the reactor, and carrying out a neutralization reaction at a temperature of 20 to 50°C and a stirring speed of 500 to 3000 rpm for 0.5 to 4 h, and adjusting the pH to 3 to 10;

[0013] (5) Add the reaction product to a certain amount of deionized water, stir at high speed for 10 to 30 min at a stirring speed of 4000 to 8000 rpm, stir at low speed for 1 to 2 h at a stirring speed of 1000 to 2000 rpm, and concentrate the product to a solid content of 15% to 35% to obtain a fluoride-containing waterborne polyurethane coating material.

[0014] The amount of the dihydroxy fluorine-containing ion monomer is 5-30 wt% of the total mass of the polyurethane. The preparation characteristics of the dihydroxy fluorine-containing ion monomer are as follows: dimethylaminoethyl methacrylate (DMAEMA) and mercaptopropylene glycol (TPG) are used as raw materials, and under ultraviolet light conditions, a photoinitiator is used to induce an addition reaction between vinyl and mercapto to generate dimethylaminoethyl methacrylate containing dihydroxy; an alkylation reaction is then performed to obtain an alkylation intermediate product, and finally an anion exchange reaction is performed to obtain the product. The specific steps are as follows:

[0015] (a) Add mercaptopropylene glycol, dimethylaminoethyl methacrylate monomer, photoinitiator benzoin dimethyl ether and solvent tetrahydrofuran into the reactor, and after dissolving into a transparent solution, introduce nitrogen for 15 minutes to remove oxygen in the bottle, and seal it; react under ultraviolet light for 0.1 to 1 hour, and the light intensity is 50 to 100%. After the reaction is completed, take out the product and remove most of the solvent with a rotary evaporator; precipitate the concentrated product in n-hexane 2 to 3 times, and finally vacuum dry it at 40 ° C for 12 to 48 hours to obtain dimethylaminoethyl methacrylate containing dihydroxyl. The molar ratio of dimethylaminoethyl methacrylate to mercaptopropylene glycol is 1:2, the mass ratio of photoinitiator benzoin dimethyl ether to the total reactant is (0.5%~1):1, and the amount of solvent tetrahydrofuran added makes the solid content of the reaction system 10 wt%.

[0016] (b) The dimethylaminoethyl bis(hydroxymethyl)acrylate synthesized in step (a) and a halogenated alkane are mixed in equal moles and reacted completely at room temperature to 60°C, and then washed and dried to obtain an alkylation intermediate.

[0017] (c) The alkylated intermediate obtained above is dissolved in deionized water to obtain reaction solution I, and then an equimolar amount of anion exchange reagent is dissolved in deionized water to obtain reaction solution II. Finally, reaction solution I and reaction solution II are mixed, reacted completely at room temperature, and centrifuged to obtain the supernatant to obtain the dihydroxy fluorine-containing ion monomer.

[0018] The dihydroxy fluoride-containing ion monomer is characterized in that the anion exchange reaction uses silver fluoride, sodium fluoride or potassium fluoride as an ion exchange reagent.

[0019] The dihydroxy fluorine-containing ion monomer is characterized in that the halogenated alkane is selected from 1-chloroalkane or 1-bromoalkane having 2 to 16 carbon atoms.

[0020] The fluorine-ion-containing aqueous polyurethane coating material is characterized in that the diisocyanate is one or a mixture of isophorone diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, lysine diisocyanate, 1,4-phenylene diisocyanate, 1,4-cyclohexane diisocyanate, 2,6-toluene diisocyanate and trimethyl 1,6-hexamethylene diisocyanate.

[0021] The fluorine-ion-containing water-based polyurethane coating material is characterized in that the macromolecular diol is one or a mixture of polypropylene glycol, polysiloxane diol, polytetramethylene glycol, polyε-caprolactone diol, polycarbonate diol and polyethylene glycol.

[0022] The dihydroxy fluorine-containing ion monomer prepared by the present invention is first prepared by ultraviolet light initiation technology to prepare dihydroxyl-containing dimethylaminoethyl methacrylate, and then prepared by alkylation reaction and ion exchange method; the monomer is introduced into the polyurethane matrix in the form of a small molecule chain extender through addition reaction to obtain a fluorine-containing waterborne polyurethane coating. The fluorine ions in the fluorine-containing waterborne polyurethane coating material prepared by the present invention can be released into the oral environment through ion exchange and supplemented from external fluorine-containing substances, and the quaternary ammonium salt cations contained therein also have excellent antibacterial properties; at the same time, the process for preparing waterborne polyurethane is simple, reproducible and universal, and the coating can be quickly cured. This patent introduces a dihydroxy fluorine-containing ion monomer prepared by clever design into polyurethane at the molecular level, and the obtained waterborne polyurethane coating can repeatedly charge and release fluorine ions to achieve the effect of effectively preventing tooth decay for a long time. DETAILED DESCRIPTION

[0023] Three embodiments of the present invention are given below to specifically illustrate a method for preparing a fluoride-containing waterborne polyurethane coating.

[0024] Embodiment 1:

[0025] The preparation of the dihydroxy fluorine-containing ion monomer is as follows: weigh 7.85 g of dimethylaminoethyl methacrylate in a weighing bottle, add 10.8 g of mercaptopropylene glycol and 0.1865 g of photoinitiator benzoin dimethyl ether, add 188 mL of tetrahydrofuran, pass nitrogen into the weighing bottle for 0.5 h, and then seal it. Irradiate with ultraviolet light for 1 h, and the light intensity is 50%. After the reaction is completed, the solvent is removed by rotary concentration, and the reaction product is precipitated in n-hexane 3 times and vacuum dried for 24 h to obtain dihydroxy dimethylaminoethyl methacrylate.

[0026] Add 13.25 g (0.05 mol) of synthesized dimethylaminoethyl bis(hydroxymethacrylate) and 3.225 g (0.05 mol) of 1-chloroethane into a 50 mL single-necked flask and stir at 50 °C for 72 h. The product was precipitated three times with a mixture of ether and ethyl acetate to obtain a white powdery solid, which was dried in a vacuum drying oven at room temperature for 24 h.

[0027] Add 1.6475 g (0.005 mol) of the intermediate product into a 50 mL single-necked flask and dissolve it in 15 mL of deionized water; dissolve 0.64 g (0.005 mol) of silver fluoride in 15 mL of deionized water, add the silver fluoride aqueous solution dropwise into the aqueous solution of the intermediate product, stir the reaction at room temperature for 2 h, centrifuge at low speed (3500 r / min) for 30 min, remove the supernatant and lyophilize it to obtain the desired fluorine-containing ion monomer.

[0028] A preparation method of a fluorine-containing waterborne polyurethane is disclosed, wherein the specific operation steps are as follows: 20.00 g of polytetrahydrofuran ether (Mn=2000) is weighed and added to a three-necked flask, vacuum dried and dehydrated at 110°C for 2 h, cooled to 85°C and protected by nitrogen, 15.54 g of isophorone diisocyanate and 135 mL of tetrahydrofuran solvent are added, and stirred for reaction for 1 h. After cooling to 70°C, 12.875 g of a dihydroxy fluorine-containing monomer small molecule chain extender and a catalyst are added to react for 1 h. After the reaction is completed, 3.086 g of dimethylol propionic acid is added and stirred for reaction for 2 h. After the reaction is completed, the reaction is cooled to 50°C, triethylamine is added to react for 30 min, and the pH is adjusted to 3-10. Finally, deionized water was added, and the mixture was emulsified at high speed for 40 min at a stirring speed of 5000 rpm using an emulsifier, and then emulsified at low speed for 1 h at a stirring speed of 2000 rpm to concentrate the reaction product to a solid content of 20% to obtain a fluorine-containing waterborne polyurethane emulsion.

[0029] Embodiment 2:

[0030] The preparation of the dihydroxy fluorine-containing ion monomer is as follows: weigh 6.28 g of dimethylaminoethyl methacrylate in a weighing bottle, add 8.64 g of mercaptopropylene glycol and 0.1492 g of photoinitiator benzoin dimethyl ether, add 150 mL of tetrahydrofuran, pass nitrogen into the weighing bottle for 0.5 h, and then seal it. Irradiate with ultraviolet light for 1 h, and the light intensity is 50%. After the reaction is completed, the solvent is removed by rotary concentration, and the reaction product is precipitated in n-hexane 3 times and vacuum dried for 24 h to obtain dihydroxy dimethylaminoethyl methacrylate.

[0031] Add 13.25 g (0.05 mol) of synthesized dimethylaminoethyl bis(hydroxymethacrylate) and 4.625 g (0.05 mol) of 1-chlorobutane into a 50 mL single-necked flask and stir at 50 °C for 72 h. The product was precipitated three times with a mixture of ether and ethyl acetate to obtain a white powdery solid, which was dried in a vacuum drying oven at room temperature for 24 h.

[0032] Add 1.1075 g (0.005 mol) of the intermediate product into a 50 mL single-necked flask and dissolve it in 15 mL of deionized water; dissolve 0.21 g (0.005 mol) of sodium fluoride in 15 mL of deionized water, add the sodium fluoride aqueous solution dropwise into the aqueous solution of the intermediate product, stir the reaction at room temperature for 2 h, centrifuge at low speed (3500 r / min) for 30 min, remove the supernatant and lyophilize it to obtain the desired fluorine-containing ion monomer.

[0033] A preparation method of a fluorine-containing waterborne polyurethane, the specific operation steps are as follows: weigh 20.00 g of polyethylene glycol (Mn=2000), add it to a three-necked flask, and vacuum dry and dehydrate at 110°C for 2 h. Cool to 85°C and protect with nitrogen, add 17.51 ​​g of diphenylmethane diisocyanate and 124 mL of tetrahydrofuran, and stir to react for 1 h. Cool to 70°C, add 4.73 g of dihydroxy fluorine-containing monomer small molecule chain extender and catalyst to react for 1 h. After the reaction is completed, add 5.098 g of dimethylol propionic acid and stir to react for 2 h. After the reaction is completed, cool to 50°C, add triethylamine to react for 30 min, and adjust the pH to 3-10. Finally, deionized water was added, and the mixture was emulsified at high speed for 40 min at a stirring speed of 5000 rpm using an emulsifier, and then emulsified at low speed for 1 h at a stirring speed of 2000 rpm to concentrate the reaction product to a solid content of 30% to obtain a fluorine-containing waterborne polyurethane emulsion.

[0034] Embodiment 3:

[0035] The preparation of the dihydroxy fluorine-containing ion monomer is as follows: weigh 9.42 g of dimethylaminoethyl methacrylate in a weighing bottle, add 12.96 g of mercaptopropylene glycol and 0.2238 g of benzoin dimethyl ether as a photoinitiator, add 226 mL of tetrahydrofuran, pass nitrogen into the weighing bottle for 0.5 h, and then seal it. Irradiate with ultraviolet light for 1 h, with a light intensity of 50%. After the reaction is completed, the solvent is removed by rotary concentration, and the reaction product is precipitated in n-hexane 3 times and vacuum dried for 24 h to obtain dihydroxy dimethylaminoethyl methacrylate.

[0036] Add 13.25 g (0.05 mol) of synthesized dimethylaminoethyl bis(hydroxymethacrylate) and 5.45 g (0.05 mol) of 1-bromoethane into a 50 mL single-necked flask and stir at room temperature for 72 h. The product is precipitated three times with a mixture of ether and ethyl acetate to obtain a white powdery solid, which is dried in a vacuum drying oven at room temperature for 24 h.

[0037] Add 1.87 g (0.005 mol) of the intermediate product into a 50 mL single-necked flask and dissolve it in 15 mL of deionized water; dissolve 0.29 g (0.005 mol) of potassium fluoride in 15 mL of deionized water, add the potassium fluoride aqueous solution dropwise into the aqueous solution of the intermediate product, stir the reaction at room temperature for 2 h, centrifuge at low speed (3500 r / min) for 30 min, remove the supernatant and lyophilize it to obtain the desired fluorine-containing ion monomer.

[0038] A preparation method of a fluorine-containing waterborne polyurethane is described, wherein the specific steps are as follows: 20.00 g of poly-ε-caprolactone diol (Mn=2000) is weighed and added to a three-necked flask, and vacuum dried and dehydrated at 110°C for 2 h. After cooling to 85°C and protected by nitrogen, 11.62 g of 1,4-cyclohexane diisocyanate and 120 mL of tetrahydrofuran are added, and the mixture is stirred and reacted for 1 h. After cooling to 70°C, 9.309 g of a dihydroxy fluorine-containing monomer small molecule chain extender and a catalyst are added, and the mixture is reacted for 1 h. After the reaction is completed, 4.96 g of dimethylol propionic acid is added, and the mixture is stirred and reacted for 2 h. After the reaction is completed, the mixture is cooled to 50°C, triethylamine is added, and the reaction is reacted for 30 min, and the pH is adjusted to 3-10. Finally, deionized water was added, and the mixture was emulsified at a high speed of 5000 rpm for 40 min, and then emulsified at a low speed of 2000 rpm for 1 h to concentrate the reaction product to a solid content of 35% to obtain a fluorine-containing waterborne polyurethane emulsion.

Claims

1. A method for preparing a fluoride-containing aqueous polyurethane coating, characterized in that The preparation method is to first obtain a polyurethane prepolymer by reacting a polyol with a diisocyanate, then add a dihydroxy fluorine-containing ion monomer as a molecular chain extender, react under the action of a catalyst, then add a hydrophilic chain extender to carry out a molecular chain extension reaction, and finally obtain the polyurethane prepolymer by neutralization reaction and aqueous emulsification operation. The specific steps are as follows: (1) Add diisocyanate and hydroxyl group of polyol into the reactor in a molar ratio of (4-10):1, add an appropriate amount of solvent, ensure that the solid content of the reaction system is 30%, the temperature is 60-90°C, the stirring speed is 500-3000 rpm, and the stirring reaction is carried out for 0.5-2 h to obtain a polyurethane prepolymer; (2) Adding dihydroxy fluorine-containing ion monomer as a molecular chain extender into the reactor, the molar ratio of dihydroxy fluorine-containing ion monomer to diisocyanate is (0.05-0.7):1, the temperature is 60-90 °C, the stirring speed is 200-2000 rpm, and the reaction is carried out under catalyst conditions for 1-5 hours; (3) Add dimethylolpropionic acid and diisocyanate into the reactor at a molar ratio of (0.02-0.7):1, at a temperature of 60-90°C, a stirring speed of 200-2000 rpm, and react for 1-4 hours under catalyst conditions; (4) adding a neutralizing agent, triethylamine or triethanolamine, to the reactor, and carrying out a neutralization reaction at a temperature of 20 to 50°C and a stirring speed of 500 to 3000 rpm for 0.5 to 4 h, and adjusting the pH to 3 to 10; (5) adding the reaction product to a certain amount of deionized water, stirring at high speed for 10 to 30 min at a stirring speed of 4000 to 8000 rpm, stirring at low speed for 1 to 2 h at a stirring speed of 1000 to 2000 rpm, concentrating the product to a solid content of 15% to 35%, and obtaining a fluoride-containing waterborne polyurethane coating material; The amount of the dihydroxy fluorine-containing ion monomer is 5-30 wt% of the total mass of the polyurethane. The preparation of the dihydroxy fluorine-containing ion monomer is characterized in that dimethylaminoethyl methacrylate and mercaptopropylene glycol are used as raw materials, and under ultraviolet light conditions, a photoinitiator is used to induce an addition reaction between vinyl and mercapto to generate dimethylaminoethyl methacrylate containing dihydroxy; an alkylation reaction is then performed to obtain an alkylation intermediate product, and finally an anion exchange reaction is performed to obtain the dihydroxy fluorine-containing ion monomer. The specific steps are as follows: (a) Add mercaptopropylene glycol, dimethylaminoethyl methacrylate monomer, photoinitiator benzoin dimethyl ether and solvent tetrahydrofuran into a reactor, and after dissolving into a transparent solution, introduce nitrogen for 15 minutes to remove oxygen in the bottle, and seal it; react under ultraviolet light for 0.1 to 1 hour, and the light intensity is 50% to 100%; after the reaction is completed, take out the product and remove most of the solvent by rotary evaporator; precipitate the concentrated product in n-hexane for 2 to 3 times, and finally vacuum dry it at 40 ° C for 12 to 48 hours to obtain dimethylaminoethyl methacrylate containing dihydroxyl; wherein the molar ratio of dimethylaminoethyl methacrylate to mercaptopropylene glycol is 1:2, the mass ratio of photoinitiator benzoin dimethyl ether to the total reactant is (0.5% to 1%):1, and the amount of solvent tetrahydrofuran added is such that the solid content of the reaction system is 10 wt%; (b) mixing bis(hydroxymethyl)methacrylate dimethylaminoethyl ester synthesized in step (a) and halogenated alkane in equal moles, reacting them completely at room temperature to 60°C, and then washing and drying to obtain an alkylation intermediate; (c) dissolving the alkylated intermediate product obtained above in deionized water to obtain reaction solution I, then dissolving an equimolar amount of anion exchange reagent in deionized water to obtain reaction solution II, finally mixing reaction solution I with reaction solution II, reacting completely at room temperature, and centrifuging to obtain the supernatant to obtain the dihydroxy fluorine-containing ion monomer, wherein the anion exchange reaction uses silver fluoride, sodium fluoride or potassium fluoride as the ion exchange reagent.

2. A dihydroxy fluorine-containing ion monomer according to claim 1, characterized in that The halogenated alkane is selected from 1-chloroalkane with 2 to 16 carbon atoms or 1-bromoalkane with 2 to 16 carbon atoms.

3. The fluorine-containing aqueous polyurethane coating material according to claim 1, characterized in that The diisocyanate is one or a mixture of isophorone diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, lysine diisocyanate, 1,4-phenylene diisocyanate, 1,4-cyclohexane diisocyanate, 2,6-toluene diisocyanate and trimethyl 1,6-hexamethylene diisocyanate.

4. The fluorine-containing aqueous polyurethane coating material according to claim 1, characterized in that The polyol is one or a mixture of several of polypropylene glycol, polysiloxane glycol, polytetramethylene glycol, polyε-caprolactone glycol, polycarbonate glycol and polyethylene glycol.