Waterborne polyurethane high polymer material and preparation method thereof

Abstract

The invention discloses a waterborne polyurethane high polymer material and a preparation method thereof.The preparation method comprises the steps that a polyethylene ethanol raw material and isocyanate are mixed to be subjected to prepolymerization reaction treatment, and a hydroxyl-terminated polyether prepolymer is obtained; carrying out hydrophilic modification treatment on the hydroxyl-terminated polyether prepolymer to obtain a carboxyl-containing modified prepolymer; carrying out neutralization and dispersion treatment on the carboxyl-containing modified prepolymer to obtain an ionic prepolymer emulsion; carrying out chain extension reaction treatment on the ionic prepolymer emulsion to obtain a waterborne polyurethane main chain emulsion; the waterborne polyurethane main chain emulsion is subjected to silane grafting modification treatment, and grafting modified polyurethane emulsion is obtained; and carrying out purification treatment on the grafted modified polyurethane emulsion to obtain a finished product of the waterborne polyurethane high polymer material. The stability of a finished product material is remarkably improved, and the application reliability of the waterborne polyurethane high polymer material in the fields of coatings, adhesives, textile coatings and the like is improved.

Description

Technical Field

[0001] The present application relates to the technical field of polyurethane materials, and in particular to a waterborne polyurethane polymer material and a preparation method thereof. Background Art

[0002] Waterborne polyurethane polymer materials have good mechanical properties and are widely used in coatings, adhesives, textile coatings and other fields. In the prior art, waterborne polyurethane is prepared by reacting polyether or polyester polyol with isocyanate to form a prepolymer, which is then subjected to a series of subsequent treatments to form a stable emulsion system. The advantage of this preparation method is that it can effectively replace traditional solvent-based polyurethane and improve adhesive properties or coating fastness.

[0003] However, the existing preparation processes generally have a significant technical problem, that is, the finished material is not stable enough, which is mainly reflected in the fact that the emulsion is prone to stratification, precipitation or particle size increase during storage or application, which directly affects the practicality and long-term performance of the material.

[0004] In the prior art, in order to solve the stability problem of finished waterborne polyurethane products, the prior art has been improved by adjusting the raw material ratio, optimizing the reaction conditions or introducing surfactants. For example, some methods increase the dispersibility of the emulsion by increasing the amount of emulsifier, or enhance the uniformity of the system by extending the stirring time. However, these improvement measures are often only effective in the short term and it is difficult to fundamentally solve the root cause of insufficient stability. Especially under high humidity, high temperature or long-term storage conditions, the microstructure of the emulsion system is prone to change, resulting in performance degradation. This phenomenon of insufficient stability not only limits the application of waterborne polyurethane in special fields, but also increases the difficulty of quality control during production and use, bringing challenges to industrial production. Summary of the invention

[0005] The purpose of the present application is to provide a waterborne polyurethane polymer material and a preparation method thereof, so as to solve the technical problem of insufficient stability of the existing waterborne polyurethane polymer materials during the preparation process.

[0006] To achieve this goal, this application adopts the following technical solutions: A method for preparing a waterborne polyurethane polymer material, comprising: The polyethanol raw material and isocyanate are mixed and subjected to a prepolymerization reaction to obtain a hydroxyl-terminated polyether prepolymer; Performing hydrophilic modification on the hydroxyl-terminated polyether prepolymer to obtain a carboxyl-modified prepolymer, wherein the grafting rate of the carboxyl-modified prepolymer is greater than 90%; The carboxyl-modified prepolymer is subjected to neutralization and dispersion treatment to obtain an ionic prepolymer emulsion, wherein the average particle size of the ionic prepolymer emulsion is 85-100 nm; The ionic prepolymer emulsion is subjected to a chain extension reaction treatment to obtain an aqueous polyurethane main chain emulsion; The aqueous polyurethane main chain emulsion is subjected to silane grafting modification treatment to obtain a grafted modified polyurethane emulsion; The grafted modified polyurethane emulsion is purified to obtain a finished waterborne polyurethane polymer material.

[0007] Furthermore, the polyethanol raw material is any one or a combination of polyethylene glycol, polypropylene glycol, polytetrahydrofuran diol or polyethylene glycol.

[0008] Furthermore, the isocyanate is any one of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate or hexamethylene diisocyanate, or a combination of several thereof.

[0009] Furthermore, the step of mixing the polyethanol raw material and isocyanate for prepolymerization to obtain the hydroxyl-terminated polyether prepolymer comprises: Put polyethylene glycol with a molecular weight of 800-900 in a reaction container, add dibutyltin dilaurate catalyst accounting for 0.2-0.5% of the weight of polyethylene glycol, heat to 75-80°C under nitrogen protection, stir at a speed of 200-250rpm, and continue to treat for 30-40 minutes to obtain activated polyether polyol; The activated polyether polyol and isophorone diisocyanate are mixed in a mass ratio of 4 to 5:1, and premixed under low-speed stirring at 50 to 60° C. to obtain a primary mixture; The primary mixture is placed in a reaction kettle, and isophorone diisocyanate is slowly added dropwise at a dropping speed of 0.8-1.2 g / min and the reaction temperature is maintained at 80-85° C. to obtain a semi-reacted prepolymer; Applying a slight positive pressure of 0.02-0.05 MPa to the semi-reacted prepolymer in the reactor, heating it to 85-90° C., and introducing low-flow nitrogen to adjust the gas phase equilibrium to obtain a refined prepolymer; The refined prepolymer is mixed with a difunctional polyether amine, and stirred for reaction at 75-80° C. to obtain a hydroxyl-terminated polyether prepolymer, wherein the mass ratio of the refined prepolymer to the difunctional polyether amine is 99:1-99.5:0.5.

[0010] Furthermore, the step of subjecting the hydroxyl-terminated polyether prepolymer to hydrophilic modification to obtain a carboxyl-modified prepolymer, wherein the grafting rate of the carboxyl-modified prepolymer is greater than 90%, comprises: Placing the hydroxyl-terminated polyether prepolymer in a cooling device, cooling it to 45-50° C., and maintaining the constant temperature for 30 minutes to obtain a low-temperature prepolymer matrix; Add 30-35 g of dimethylol propionic acid and 40-50 mL of acetone into the low-temperature prepolymer matrix and mix to obtain a monomer mixed prepolymer; The monomer-mixed prepolymer is heated to 65-70° C. in a nitrogen environment, and 0.5-1 g of triethylamine is added as a catalyst, stirred at 500 rpm for 15 minutes, and reacted at 70° C. for 1 hour to obtain a catalytically modified prepolymer; The catalytic modified prepolymer is heated to 75-80° C., 5-10 mL of N,N-dimethylformamide is added as a cosolvent, and the change of the characteristic peak of the carboxyl group in the monomer mixed prepolymer at 1710 cm⁻¹ is monitored by Fourier transform infrared spectroscopy. When the intensity of the characteristic peak of the carboxyl group reaches a preset value, heating is stopped to obtain a carboxyl-containing modified prepolymer, wherein the preset value is that the intensity of the characteristic peak of the carboxyl group reaches more than 95% of the initial characteristic peak intensity of the carboxyl group in the monomer mixed prepolymer.

[0011] Further, the step of neutralizing and dispersing the carboxyl-modified prepolymer to obtain an ionic prepolymer emulsion, wherein the average particle size of the ionic prepolymer emulsion is 85 to 100 nm, comprises: Cooling the carboxyl-modified prepolymer to 35-40° C. at a cooling rate of 5° C. / min to obtain a low-temperature carboxyl-modified prepolymer; Adding 10-15 g of triethylamine as a neutralizing agent to the low-temperature carboxyl-containing prepolymer and stirring, and determining the degree of neutralization by acid-base titration to reach 93-97%, thereby obtaining a neutralized prepolymer; Slowly adding 50-70 mL of deionized water to the neutralized prepolymer for low-speed dispersion treatment, controlling the water addition speed to 1-2 mL / min, to obtain a primary dispersion; 5-10 g of acetone was added to the primary dispersion to dilute it so that the solid content was controlled at 35-40%. The adjusted dispersion was placed in a constant temperature still box and kept at a constant temperature of 25-30° C. for 2-3 hours to obtain an ionic prepolymer emulsion with an average particle size of 85-100 nm.

[0012] Furthermore, the step of subjecting the ionic prepolymer emulsion to a chain extension reaction to obtain an aqueous polyurethane main chain emulsion comprises: The ionic prepolymer emulsion is heated to 55-65° C. and maintained for 30 minutes to allow the ion clusters in the emulsion to fully dissociate, and 8-12 g of ethylenediamine is added dropwise at a rate of 0.4-0.6 g / min as a first chain extender to initially extend the molecular chain to obtain a primary chain extension emulsion; Add 5-10 g of hydroxyl-containing polyether polyol to the primary chain extension emulsion, maintain the temperature at 60-70° C. for reaction for 1 hour, stabilize the viscosity of the system at 400-500 mPa·s, and obtain a steady-state chain extension emulsion; 3-5 g of diaminobutylene as a second chain extender is added dropwise to the stable chain extension emulsion at a rate of 0.3-0.5 g / min to further graft and extend the molecular chain to obtain the waterborne polyurethane main chain emulsion.

[0013] Furthermore, the step of subjecting the aqueous polyurethane main chain emulsion to silane grafting modification to obtain a grafted modified polyurethane emulsion comprises: At 70° C., 15 to 20 g of γ-aminopropyltriethoxysilane is added dropwise to the aqueous polyurethane main chain emulsion at a rate of 0.5 to 0.8 g / min, and stirred to initially graft the silane monomer to the main chain to obtain a primary grafted emulsion; Adding 0.5-1 g of an organic tin catalyst to the primary grafting emulsion, so that the silane grafting rate reaches 60-70% as measured by infrared spectroscopy, to obtain a catalytic grafting emulsion; 5-8 g of vinyltrimethoxysilane was added dropwise to the catalytic grafting emulsion at a rate of 0.3 g / min, and the silicon content was determined to be 1.5-2.5 wt % by elemental analysis to obtain a grafted modified polyurethane emulsion.

[0014] Furthermore, the step of purifying the grafted modified polyurethane emulsion to obtain a finished waterborne polyurethane polymer material comprises: Adding 3-5 g of a polyether-modified siloxane defoamer and 2-4 g of a hydroxyethyl cellulose thickener to the graft-modified polyurethane emulsion to obtain a pre-adjusted emulsion; The pre-adjusted emulsion is mixed with a sodium hydroxide solution, and the pH value is adjusted to 7.0-7.5 to obtain a neutralized emulsion; Under the conditions of vacuum degree of 0.07-0.09 MPa and temperature of 45-55° C., the neutralized emulsion is subjected to reduced pressure distillation treatment until the acetone content in the neutralized emulsion is less than 0.1%, thereby obtaining a finished waterborne polyurethane polymer material.

[0015] The present application also discloses a waterborne polyurethane polymer material, which is prepared by the preparation method of the waterborne polyurethane polymer material as described in any one of the above items, and the waterborne polyurethane polymer material comprises: The polyurethane main chain is composed of a terminal hydroxyl polyether prepolymer, a carboxyl-modified prepolymer, a chain extender and a silane-grafted modified substance; a hydrophilic modified monomer is used to improve the hydrophilicity and dispersibility of the polyurethane; and a silane-grafted substance is used to improve the water resistance and wear resistance of the polyurethane; wherein, calculated by mass ratio, in the waterborne polyurethane polymer material, the hydrophilic modified monomer accounts for 7% to 10%, the silane-grafted substance accounts for 2% to 5%, and the rest is the polyurethane main chain.

[0016] Compared with the prior art, this application has the following beneficial effects: The preparation method of the waterborne polyurethane polymer material of the present application forms a terminal hydroxyl polyether prepolymer through a prepolymerization reaction of a polyethanol raw material and an isocyanate, and then introduces a carboxyl-modified prepolymer with a high grafting rate (greater than 90%) through a hydrophilic modification treatment, thereby enhancing the uniformity and hydrophilicity of the molecular structure. The ionic prepolymer emulsion obtained by the neutralization and dispersion treatment has an average particle size of 85 to 100 nm, which improves the dispersibility of the emulsion and significantly reduces the tendency of the microstructure to change under harsh conditions; further, through a chain extension reaction and a silane grafting modification treatment, the grafted modified polyurethane emulsion formed introduces stable chemical bonding at the molecular level, so that the emulsion system can still maintain excellent anti-stratification and anti-precipitation capabilities under high humidity, high temperature or long-term storage conditions; the finished material obtained by the purification treatment retains the good mechanical properties and environmental protection characteristics of the waterborne polyurethane, and solves the core problem of insufficient stability mentioned in the background technology.

[0017] The present invention significantly improves the stability of the finished material, overcomes the defects of the emulsion system in the prior art that it is easy to have stratification, precipitation or increase in particle size during storage or application, thereby ensuring the long-term performance and practicality of the material, and improving the application reliability of waterborne polyurethane polymer materials in the fields of coatings, adhesives and textile coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0019] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which this application can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by this application, should still fall within the scope of the technical contents disclosed in this application.

[0020] Figure 1 It is a schematic diagram of the overall steps of the preparation method of waterborne polyurethane polymer material; Figure 2 A schematic diagram of the steps of an embodiment of a method for preparing a waterborne polyurethane polymer material; Figure 3 The present invention is a schematic diagram of the steps of another embodiment of a method for preparing a waterborne polyurethane polymer material. DETAILED DESCRIPTION

[0021] In order to make the purpose, features, and advantages of the invention of this application more obvious and easy to understand, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the embodiments described below are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0022] In the description of the present application, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0023] The technical solution of the present application is further explained below with reference to the accompanying drawings and through specific implementation methods.

[0024] refer to Figures 1 to 3 The present application provides a method for preparing a waterborne polyurethane polymer material, comprising: S1: mixing a polyethanol raw material and an isocyanate to perform a prepolymerization reaction to obtain a hydroxyl-terminated polyether prepolymer; In step S1, the polyethanol raw material is mixed with isocyanate to obtain a hydroxyl-terminated polyether prepolymer. Polyethanol is a polymer compound containing hydroxyl groups. As one of the raw materials in the synthesis of polyurethane, it contains multiple hydroxyl (-OH) groups in its chemical structure. These hydroxyl groups can react with isocyanate to form the main chain structure of polyurethane. In this step, the mixture of polyethanol and isocyanate is prepolymerized under specific temperature, pressure and reaction conditions. In the prepolymerization reaction, isocyanate (using a chemical substance with an isocyanate group) reacts with the hydroxyl group of polyethanol to form a hydroxyl-terminated polyether prepolymer. The specific reaction process involves the chemical reaction between the -N=C=O group of the isocyanate and the -OH group in the polyethanol molecule to form an ester bond (-NH-COO-), thereby obtaining a polyurethane segment containing an isocyanate group and a hydroxyl group. In this process, since the hydroxyl group of polyethanol is relatively active and the reaction rate is relatively fast, polyethanol diisocyanate can be effectively converted into a prepolymer under the control of reaction temperature and time. According to different raw material characteristics and desired polyurethane properties, the molar ratio of polyethanol diisocyanate is adjusted according to practical experience, and can be set to a molar ratio of polyethanol to isocyanate of 1:1.2-1.5, which can ensure a higher terminal hydroxyl content after the reaction, while avoiding excessive unreacted isocyanate groups remaining, which affects the stability and performance of the subsequent polyurethane structure.

[0025] S2: performing hydrophilic modification on the hydroxyl-terminated polyether prepolymer to obtain a carboxyl-modified prepolymer, wherein the grafting rate of the carboxyl-modified prepolymer is greater than 90%; In step S2, the hydroxyl-terminated polyether prepolymer is reacted with one or more chemical reagents with hydrophilic groups, which may be compounds containing carboxyl groups (-COOH) or similar functional groups. Specifically, organic acids, anhydrides or other chemical reagents with carboxyl groups can be selected to react with the hydroxyl-terminated polyether prepolymer under certain temperature and conditions to generate a polyurethane structure with carboxyl groups. Through esterification reaction, addition reaction and other methods, carboxyl groups with strong hydrophilicity are introduced into the prepolymer chain segments, so that they can be well dispersed in water-based media, making their molecular segments more hydrophilic, and promoting the subsequent emulsion formation and stability. Especially in industrial applications, hydrophilic modification can effectively reduce the precipitation problem of polyurethane in applications such as water-based coatings and adhesives, and improve the stability and long-term storage of the emulsion. It is worth noting that the modification reaction in step S2 needs to achieve a high grafting rate, that is, the grafting rate of the carboxyl-modified prepolymer is greater than 90%, that is, in the hydrophilic modification process, almost all the terminal hydroxyl groups are involved in the modification reaction, and hydrophilic groups such as carboxyl groups are generated. By optimizing the reaction conditions, the efficiency of the modification reaction can be improved, thereby achieving a higher grafting rate.

[0026] S3: neutralizing and dispersing the carboxyl-modified prepolymer to obtain an ionic prepolymer emulsion, wherein the average particle size of the ionic prepolymer emulsion is 85-100 nm; In step S3, during the neutralization process, an alkaline substance is used to neutralize the carboxyl group in the prepolymer, and the neutralizer may include sodium hydroxide (NaOH), potassium hydroxide (KOH) or an organic amine compound. By adding an appropriate amount of neutralizer, the carboxyl group (-COOH) reacts with the cation in the neutralizer to generate a negatively charged carboxylate group (-COO⁻), so that the polyurethane molecules are negatively charged, thereby giving the emulsion a certain charge, so that the particles repel each other, and avoid the aggregation or precipitation of polyurethane molecules in water. After the neutralization reaction is completed, the neutralized polyurethane system is dispersed into fine particles, which can be accomplished by mechanical stirring, ultrasonic dispersion or high shear mixing. In this process, the neutralized polyurethane solution is dispersed into uniform microparticles, that is, between 85 and 100 nm, through the action of high shear force, and the particle size can be finely controlled by adjusting parameters such as stirring speed, ultrasonic treatment time or temperature.

[0027] S4: performing a chain extension reaction on the ionic prepolymer emulsion to obtain an aqueous polyurethane main chain emulsion; In step S4, the chain extension reaction is to further extend the molecular chain of the polyurethane by introducing a chain extender or a cross-linking agent, increase the molecular weight of the polyurethane, and optimize its mechanical properties, thermal stability and durability. Specifically, the chain extension reaction is to add a chain extender to the ionic prepolymer emulsion, extend the prepolymer chain through a chemical reaction, and finally form a polyurethane main chain emulsion with a longer chain segment. In this process, a suitable chain extender is selected. The chain extender used is a chemical substance containing active hydrogen atoms, such as diamines, diols or other compounds containing multiple amino or hydroxyl groups, which reacts with the isocyanate groups in the prepolymer through its active hydrogen atoms to form a longer polymer chain. Specifically, the realization of the chain extension reaction depends on the addition reaction of active hydrogen-containing substances such as amino or hydroxyl groups with unreacted isocyanate groups (-NCO) in the prepolymer. These amino or hydroxyl substances will react with isocyanate groups to form longer molecular chains. Through this reaction, the molecular structure of the prepolymer is expanded to form a polyurethane main chain with a higher molecular weight and longer chain segments, which can increase the molecular weight of the polyurethane and improve its mechanical properties and other related properties, such as elasticity and tensile strength.

[0028] S5: subjecting the aqueous polyurethane main chain emulsion to silane grafting modification treatment to obtain a grafted modified polyurethane emulsion; In step S5, silane grafting modification is to graft silane groups on the polyurethane molecular chain to make the polyurethane have excellent surface properties and stronger functionality. When performing silane grafting modification, a compound with an active silane group, such as aminosilane, epoxysilane or allylsilane, is selected. These silane groups react with amino, hydroxyl or other active groups on the polyurethane molecular chain to form a covalently bonded structure, so that the silane group can be firmly grafted onto the polyurethane molecular chain, thereby giving the polyurethane molecule special functions. In specific operations, silane compounds can be added to the aqueous polyurethane main chain emulsion, which can be carried out at a temperature of 80°C to 120°C to ensure that the silane group can react with the hydroxyl or amino group on the polyurethane molecular chain, thereby achieving silane grafting. During the reaction process, the silane group reacts chemically with the active group on the polyurethane chain to form a strong covalent bond connection, which significantly improves the surface properties of the polyurethane, especially in terms of improving hydrophobicity, enhancing adhesion and improving weather resistance. The modification treatment of silane grafting involves changes in the physical properties and stability of the polyurethane emulsion. For example, after silane grafting, the particles in the polyurethane emulsion may aggregate to a certain extent, so it is necessary to accurately control the reaction conditions during the grafting process to avoid the destruction of the emulsion dispersion system. During the operation, the reaction time and temperature can be optimized and adjusted according to the specific type of silane compound, the composition of the polyurethane emulsion, and the desired final product characteristics.

[0029] S6: Purify the grafted modified polyurethane emulsion to obtain a finished waterborne polyurethane polymer material.

[0030] In step S6, purification treatment is to remove impurities in the aqueous polyurethane emulsion, which may include unreacted monomers, catalyst residues, low molecular weight by-products and side reactions produced in the reaction. In actual operation, for example, polyethanol, isocyanate or larger polymer aggregates that are not fully reacted are filtered. In the purification process, the pH value and temperature of the emulsion are controlled to avoid excessively high or low acidity and alkalinity causing damage to the polyurethane molecular chain structure, affecting the final performance. After such purification treatment, the aqueous polyurethane polymer material obtained will have better stability and higher purity, and is suitable for various application fields such as coatings, adhesives, elastomers, etc.

[0031] In one embodiment, the polyethanol raw material is any one or a combination of polyethylene glycol, polypropylene glycol, polytetrahydrofuran diol or polyethylene glycol. The isocyanate is any one or a combination of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate or hexamethylene diisocyanate.

[0032] In the present embodiment, the polyethanol raw material can selectively use polyethylene glycol, polypropylene glycol, polytetrahydrofuran diol or polyethylene glycol, etc. These polyethanol raw materials have different segment lengths and chemical structures, and can be selected and combined according to the performance requirements of the final product. For example, polyethylene glycol has a relatively flexible segment, which can improve the elasticity and flexibility of polyurethane; polytetrahydrofuran diol has higher rigidity and heat resistance, and is suitable for application scenarios requiring higher strength and thermal stability. By selecting a suitable polyethanol raw material, the performance of the polyurethane material can be adjusted to meet different application requirements. The isocyanate can selectively use diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate or hexamethylene diisocyanate, etc. These isocyanates have different reactivity and chemical structures, which can affect the crosslinking density and molecular structure of the polyurethane segment. For example, diphenylmethane diisocyanate has high reactivity and can generate polyurethane with high crosslink density, which is suitable for products that require high strength and hardness; isophorone diisocyanate has good weather resistance and chemical resistance, which is suitable for outdoor applications or occasions that require high durability. By selecting the right isocyanate, the performance of polyurethane materials can be further adjusted to meet specific application requirements.

[0033] In one embodiment, reference Figure 2 The step of mixing the polyethanol raw material and the isocyanate for prepolymerization to obtain a hydroxyl-terminated polyether prepolymer comprises: S11: placing polyethylene glycol with a molecular weight of 800-900 in a reaction container, adding dibutyltin dilaurate catalyst accounting for 0.2-0.5% of the weight of the polyethylene glycol, heating to 75-80° C. under nitrogen protection, stirring at a speed of 200-250 rpm, and continuously treating for 30-40 minutes to obtain an activated polyether polyol; S12: mixing the activated polyether polyol and isophorone diisocyanate in a mass ratio of 4 to 5:1, and premixing them under low-speed stirring at 50 to 60° C. to obtain a primary mixture; S13: placing the primary mixture in a reaction kettle, slowly dropping isophorone diisocyanate at a dropping speed of 0.8-1.2 g / min, and maintaining the reaction temperature at 80-85° C. to obtain a semi-reacted prepolymer; S14: applying a slight positive pressure of 0.02-0.05 MPa to the semi-reacted prepolymer in the reactor, heating it to 85-90° C., and introducing low-flow nitrogen to adjust the gas phase equilibrium to obtain a refined prepolymer; S15: mixing the refined prepolymer with a difunctional polyetheramine, and performing a stirring reaction at 75-80° C. to obtain a hydroxyl-terminated polyether prepolymer, wherein the mass ratio of the refined prepolymer to the difunctional polyetheramine is 99:1-99.5:0.5.

[0034] In this embodiment, polyethylene glycol (PEG) is used as a starting material, and polyethylene glycol with a molecular weight of 800-900 is placed in a reaction vessel, and dibutyltin dilaurate catalyst is added to the polyethylene glycol, and the amount of the catalyst is 0.2-0.5% of the mass of the polyethylene glycol. Under nitrogen protection, the reaction system is heated to 75-80°C, and the stirring speed is set between 200-250 rpm to promote the reaction of polyethylene glycol and isocyanate to generate a polyether polyol with active hydroxyl groups. The mass ratio of the activated polyether polyol to isophorone diisocyanate is 4:1 to 5:1, and low-speed stirring and mixing are performed at 50-60°C to obtain a primary mixture. Isophorone diisocyanate, as a cross-linking agent for the reaction, can react with the hydroxyl groups in the polyethylene glycol molecule to generate a prepolymer. By controlling the stirring speed and temperature, the reaction can be ensured to be uniform and the raw materials can be fully reacted. The primary mixture is placed in a reactor, and isophorone diisocyanate is slowly added dropwise. The rate of addition is controlled between 0.8-1.2 g / min, and the reaction temperature is maintained at 80-85°C. The semi-reacted prepolymer obtained has a certain degree of polymerization, but has not yet reacted completely, and some unreacted isocyanate groups are still retained. After the reaction is completed, a slight positive pressure (0.02-0.05 MPa) is applied to the semi-reacted prepolymer in the reactor and continued to be heated to 85-90°C. At this time, a low flow of nitrogen is introduced to adjust the gas phase equilibrium to promote the reaction of isocyanate, and the volatile substances that may be formed during the reaction process, such as solvents or low molecular weight compounds, are removed by adjusting the gas phase equilibrium. At the same time, the accumulation of by-products generated in the reaction can also be avoided, and a refined prepolymer is obtained, and the refined prepolymer is mixed with a difunctional polyetheramine for reaction. The difunctional polyetheramine has two amino groups, which can react with isocyanate groups to further generate a terminal hydroxyl polyether prepolymer. The reaction is stirred at 75-80°C, and the mass ratio of the bifunctional polyetheramine to the refined prepolymer is controlled between 99:1 and 99.5:0.5. Through this reaction, the terminal of the polyurethane can be functionalized into a hydroxyl group, thereby making the final polyurethane have better hydrophilicity and higher reactivity.

[0035] In one embodiment, reference Figure 3 The step of subjecting the hydroxyl-terminated polyether prepolymer to hydrophilic modification to obtain a carboxyl-modified prepolymer, wherein the grafting rate of the carboxyl-modified prepolymer is greater than 90%, comprises: S21: placing the hydroxyl-terminated polyether prepolymer in a cooling device, cooling it to 45-50° C., and maintaining the constant temperature for 30 minutes to obtain a low-temperature prepolymer matrix; S22: adding 30-35 g of dimethylol propionic acid and 40-50 mL of acetone to the low-temperature prepolymer matrix and mixing to obtain a monomer mixed prepolymer; S23: heating the monomer-prepolymer mixture to 65-70° C. in a nitrogen environment, adding 0.5-1 g of triethylamine as a catalyst, stirring at 500 rpm for 15 minutes, and continuing the reaction at 70° C. for 1 hour to obtain a catalytically modified prepolymer; S24: heating the catalytic modified prepolymer to 75-80° C., adding 5-10 mL of N,N-dimethylformamide as a cosolvent, and monitoring the change of the characteristic peak of the carboxyl group in the monomer mixed prepolymer at 1710 cm⁻¹ by Fourier transform infrared spectroscopy. When the intensity of the characteristic peak of the carboxyl group reaches a preset value, heating is stopped to obtain a carboxyl-containing modified prepolymer, wherein the preset value is that the intensity of the characteristic peak of the carboxyl group reaches more than 95% of the initial characteristic peak intensity of the carboxyl group in the monomer mixed prepolymer.

[0036] In this embodiment, the hydroxyl-terminated polyether prepolymer is cooled, the hydroxyl-terminated polyether prepolymer is placed in a cooling device, and the temperature is reduced to 45-50°C, and the temperature is maintained for 30 minutes, and the temperature of the reaction system is adjusted to a lower temperature range, so that when a hydrophilic monomer (such as dimethylol propionic acid) is added later, the reaction rate can be effectively controlled, and the generation of by-products or incomplete reactions caused by too fast reactions can be prevented. Dimethylol propionic acid (DMPA) is a hydrophilic monomer, and 30-35g of dimethylol propionic acid and 40-50mL of acetone are added to the low-temperature prepolymer matrix. Acetone as a solvent can help dissolve the reactants and provide a suitable dissolution environment. By fully stirring, dimethylol propionic acid and hydroxyl-terminated polyether prepolymer can be uniformly mixed to form a monomer mixed prepolymer. After the mixing is completed, the monomer mixed prepolymer is heated to 65-70°C, and 0.5-1g of triethylamine is added as a catalyst, and it is carried out under a nitrogen environment. The role of nitrogen is to prevent oxygen in the air from affecting the progress of the reaction. Subsequently, the reaction system was stirred at 500 rpm for 15 minutes to ensure uniform mixing of the reactants, and the reaction was continued at 70 °C for 1 hour to promote the conversion of hydroxyl groups to carboxyl groups. The catalytically modified prepolymer was heated to 75-80 °C, and 5-10 mL of N,N-dimethylformamide (DMF) was added as a cosolvent. N,N-dimethylformamide is a polar solvent used to dissolve the intermediates in the reaction and increase the solubility of the reactants, thereby accelerating the reaction. At this time, the carboxyl characteristic peak (1710 cm⁻¹) in the monomer mixed prepolymer was monitored by Fourier transform infrared spectroscopy (FTIR) to track the generation process of the carboxyl group in real time. Fourier transform infrared spectroscopy is an analytical technique that can detect changes in chemical structure. During this process, FTIR can monitor the changes in the carboxyl characteristic peak and calculate the progress of the reaction by comparing the initial carboxyl characteristic peak intensity in the monomer mixed prepolymer with the peak intensity after the reaction. When the intensity of the characteristic peak of the carboxyl group reaches a preset value, that is, it reaches more than 95% of the initial characteristic peak intensity of the carboxyl group in the monomer mixed prepolymer, the reaction can be stopped. At this time, the reaction is completed and a carboxyl-containing modified prepolymer is obtained. Through the above steps, it can be ensured that the final carboxyl-containing modified prepolymer has a high grafting rate of more than 90%. The acid value (i.e., carboxyl content) of the modified prepolymer is determined by acid-base titration to be 25~30mg KOH / g, which further confirms its degree of modification.

[0037] In another embodiment, the step of monitoring the change of the characteristic peak of the carboxyl group in the monomer mixed prepolymer at 1710 cm⁻¹ by Fourier transform infrared spectroscopy, and stopping heating when the intensity of the characteristic peak of the carboxyl group reaches a preset value, to obtain a carboxyl-containing modified prepolymer, wherein the preset value is that the intensity of the characteristic peak of the carboxyl group reaches more than 95% of the initial characteristic peak intensity of the carboxyl group in the monomer mixed prepolymer, further comprises: Perform real-time acquisition and processing of Fourier transform infrared spectroscopy on the monomer mixed prepolymer to obtain an initial spectral data matrix. Specifically: Continuously collect the signal of the carboxyl characteristic peak in real time and construct a data matrix. Use a Fourier transform infrared spectrometer to continuously collect the infrared absorption spectrum near 1710 cm⁻¹ at 1-second intervals to generate spectral intensity data containing a time series. Arrange the collected spectral data according to the time stamp t (unit: second) to form a two-dimensional matrix M, where M[i, j] represents the intensity value of the jth wavenumber point in the ith acquisition. The initial carboxyl characteristic peak intensity I 0 is defined as the maximum value at 1710 cm⁻¹ when t = 0. Initialize the matrix M 0 After that, calculate the average spectral intensity at each moment through a sliding window (window size: 5 acquisitions) to generate a smoothed initial spectral data matrix M 1 . If a noise signal (intensity fluctuation exceeds 10%) is detected during the acquisition process, then eliminate the abnormal points and complete them with linear interpolation of the front and back data to ensure the continuity of M 1 .

[0038] Perform dynamic difference processing on the time series characteristics according to the initial spectral data matrix to obtain a carboxyl intensity change curve. Specifically: Extract the change trend of the carboxyl characteristic peak over time, perform a first-order difference calculation on the intensity values of the 1710 cm⁻¹ wavenumber point in M 1 to reflect the rate change of the carboxyl grafting reaction. Let I(t) be the carboxyl intensity at time t, then the difference value ΔI(t) = I(t) - I(t - 1), and construct a time series vector V 1 , where V 1 [t] = ΔI(t). Apply the exponential smoothing method to V 1 , with the smoothing parameter α = 0.3, and calculate the smoothed intensity change S(t) = α·ΔI(t) + (1 - α)·S(t - 1) to generate a carboxyl intensity change curve C 1 . If S(t) shows a downward trend St < St - 1 < S(t - 2) at three consecutive time points, then mark it as a reaction rate slowdown point for subsequent analysis.

[0039] Perform piecewise linear fitting on the carboxyl intensity change curve to obtain reaction stage division data. Specifically: Divide the reaction process into multiple stages to analyze the carboxyl grafting dynamics. Use the least squares method to perform piecewise linear fitting on C 1 to divide it into an initial acceleration stage, a stable growth stage, and a saturation approaching stage. Apply an iterative breakpoint detection algorithm to C 1 , set the breakpoint threshold as ΔS = 0.05, calculate the slope ki and intercept bi of each fitting segment, and generate a piecewise function F(t) = ki·t + bi (t ∈ [t i , t i+1]). Iterate from t = 0 and detect the rate of change of S (t). When |k i -k i+1 When |>ΔS, the breakpoint tᵢ is determined and the reaction stage division data D is obtained 1 ,If more than 3 stages are detected, adjacent segments with slope differences less than 0.01 are merged to ensure the ,reasonableness of the division.

[0040] According to the reaction stage division data, the carboxyl characteristic peak intensity is normalized and corrected to obtain a correction intensity sequence; specifically, the influence of the spectral baseline drift in different reaction stages is eliminated. 1 At each stage in , the baseline offset is calculated and the intensity is normalized. Let the initial intensity of a stage be I(t 0 ), the final intensity is I(t n ), baseline shift ΔB = Iᵢt n -Iᵢ(t 0 ) / (t n -t 0 ), correction intensity Iᵢ'(t)=Iᵢ(t)-ΔB·(tt 0 ), generate the correction intensity sequence S 2 For S 2 Apply z-score standardization, calculate the mean μ and standard deviation σ, and get S 2 '(t)=S 2 (t-μ) / σ, to ensure that the intensity of each stage is comparable. If σ>0.1 in a certain stage, the baseline shift of this segment is recalculated and iterated until σ converges.

[0041] The correction intensity sequence is subjected to dynamic threshold comparison processing to obtain the grafting completion time point; specifically: based on S 2 'Compare dynamically with the preset value (95% initial strength) and determine the completion time based on the reaction rate. 0 95% is the threshold value T=0.95·I 0 , traverse S 2 '(t), when S 2 '(t)≥T and S at the next 5 time points 2 '(t+1) to S 2 When (t+5) is ≥ T, record t as the grafting completion time point t x Introduce rate constraints. If S(t) < 0.01 at time t (the reaction tends to saturation), verify t in advance. x , to avoid misjudgment. x If the deviation from the above reaction rate slowdown point exceeds 10 minutes, the threshold T is readjusted to 0.96·I 0 And repeat the calculation.

[0042] According to the grafting completion time point, the catalytic modified prepolymer is subjected to cooling termination treatment to obtain a carboxyl-containing modified prepolymer; specifically: at t x Immediately cool down and remove the nitrogen environment to solidify the modified product. x Calculate the cooling rate R = (75℃-25℃) / (t x +300 seconds -t x ), the prepolymer is cooled linearly with R to generate a temperature curve T(t)=75-R·(tt x ). Monitor the temperature in real time, stop cooling when T(t)≤25℃, and record the total reaction time t_total=t x +300 seconds to obtain the carboxyl-modified prepolymer P 1 If t_total exceeds expectations (>2 hours), adjust R according to T(t) and shorten the cooling time to t_total = 1.5 hours.

[0043] In one embodiment, the step of neutralizing and dispersing the carboxyl-modified prepolymer to obtain an ionic prepolymer emulsion, wherein the average particle size of the ionic prepolymer emulsion is 85 to 100 nm, comprises: Cooling the carboxyl-modified prepolymer to 35-40° C. at a cooling rate of 5° C. / min to obtain a low-temperature carboxyl-modified prepolymer; Adding 10-15 g of triethylamine as a neutralizing agent to the low-temperature carboxyl-containing prepolymer and stirring, and determining the degree of neutralization by acid-base titration to reach 93-97%, thereby obtaining a neutralized prepolymer; Slowly adding 50-70 mL of deionized water to the neutralized prepolymer for low-speed dispersion treatment, controlling the water addition speed to 1-2 mL / min, to obtain a primary dispersion; 5-10 g of acetone was added to the primary dispersion to dilute it so that the solid content was controlled at 35-40%. The adjusted dispersion was placed in a constant temperature still box and kept at a constant temperature of 25-30° C. for 2-3 hours to obtain an ionic prepolymer emulsion with an average particle size of 85-100 nm.

[0044] In this embodiment, the carboxyl-modified prepolymer is cooled to 35-40°C at a cooling rate of 5°C / min. At low temperatures, the reaction rate is slow, and triethylamine (TEA) is added as a neutralizer. Triethylamine can react with the carboxyl group in the prepolymer to form an ionized polymer, thereby improving its water solubility. In this embodiment, 10-15g of triethylamine is added to the carboxyl-containing prepolymer cooled to 35-40°C, and the prepolymer is uniformly mixed by stirring. In this process, the neutralization degree is determined by acid-base titration in the embodiment to reach 93-97%. The acid-base titration method can accurately measure the degree of neutralization reaction, ensure that the neutralization reaction is fully carried out, and ensure that the generated emulsion has good ionization characteristics. Deionized water is slowly added to the neutralized prepolymer, and a low-speed dispersion treatment is performed, and the speed of adding water is controlled at 1-2mL / min. Through dispersion, the polymer particles are gradually wrapped by water to form a primary dispersion. 5-10 g of acetone is added to the primary dispersion. Acetone as a solvent can help reduce the viscosity of the emulsion and adjust its solid content to meet the requirement of 35-40%. It is worth noting that this is the second time to add acetone. Compared with the acetone used as a solvent in the previous embodiment, the addition of acetone this time is mainly used to dilute the emulsion and adjust the solid content of the emulsion, so as to obtain an emulsion with uniform dispersion and good stability. Subsequently, the adjusted dispersed emulsion is placed in a constant temperature static box and kept at a constant temperature of 25-30 ° C for 2-3 hours. During the static process, the distribution of particle size will tend to be uniform, and the particles will gradually reach the required average particle size range. Through this constant temperature static treatment, the average particle size of the obtained ionic prepolymer emulsion is 85-100 nm, and the particle size distribution of the emulsion tends to be uniform and stable.

[0045] In one embodiment, the step of subjecting the ionic prepolymer emulsion to a chain extension reaction to obtain an aqueous polyurethane main chain emulsion comprises: The ionic prepolymer emulsion is heated to 55-65° C. and maintained for 30 minutes to allow the ion clusters in the emulsion to fully dissociate, and 8-12 g of ethylenediamine is added dropwise at a rate of 0.4-0.6 g / min as a first chain extender to initially extend the molecular chain to obtain a primary chain extension emulsion; Add 5-10 g of hydroxyl-containing polyether polyol to the primary chain extension emulsion, maintain the temperature at 60-70° C. for reaction for 1 hour, stabilize the viscosity of the system at 400-500 mPa·s, and obtain a steady-state chain extension emulsion; 3-5 g of diaminobutylene as a second chain extender is added dropwise to the stable chain extension emulsion at a rate of 0.3-0.5 g / min to further graft and extend the molecular chain to obtain the waterborne polyurethane main chain emulsion.

[0046] In this embodiment, the ionic prepolymer emulsion is heated to 55-65°C and maintained for 30 minutes to fully dissociate the ion clusters in the emulsion. The dissociation of the ion clusters can promote the subsequent chain extension reaction. By dripping 8-12g of ethylenediamine (EDA) as the first chain extender at a rate of 0.4-0.6g / min, the molecular chain is initially extended. Ethylenediamine is an amine chain extender that can react with the isocyanate groups in the polyurethane molecules to form new chemical bonds, thereby extending the molecular chain. By controlling the dripping rate, the stability of the reaction between ethylenediamine and the prepolymer can be ensured, and the reaction is too violent to cause uneven polymers. The reaction time is about 30 minutes. After the initial chain extension, the length of the molecular chain is extended, thereby obtaining a primary chain extension emulsion. The temperature of the primary chain extension emulsion is maintained at 60-70°C and reacted for 1 hour, and 5-10g of hydroxyl-containing polyether polyol is added. The hydroxyl groups react with the isocyanate groups in the prepolymer to further extend the molecular chain, and the flexibility and heat resistance of the system can also be increased. At this time, the viscosity of the system will also gradually increase. In this way, the molecular weight of the polyurethane system is further improved, and the viscosity of the system is stabilized between 400-500mPa·s, indicating that the molecular chain has been fully extended and stabilized. Add diaminodiamine (3-5g at a rate of 0.3-0.5g / min) as the second chain extender to the stable chain extension emulsion to further extend the molecular chain. The main function of diaminodiamine is to further graft and extend the molecular chain by reacting with the isocyanate group. This reaction can further increase the molecular weight of the polyurethane molecule, make the molecular chain of the emulsion longer, improve the mechanical properties and chemical resistance of the polymer, and effectively improve the molecular weight of the obtained waterborne polyurethane main chain emulsion, the system viscosity is stable, and it has good dispersibility and high molecular weight. Through similar treatment, the chain extension reaction in this embodiment increases the molecular weight of the waterborne polyurethane (detected by gel permeation chromatography) and controls the viscosity of the emulsion within the desired range. For example, the final emulsion has an average molecular weight between 50,000 and 60,000, and the viscosity reaches the range of 500-600 mPa·s. The amino content of the waterborne polyurethane main chain emulsion is 0.5-1.0 mmol / g as detected by chemical titration, which also illustrates the degree and effectiveness of the chain extension reaction.

[0047] In one embodiment, the step of subjecting the aqueous polyurethane main chain emulsion to silane grafting modification to obtain a grafted modified polyurethane emulsion comprises: At 70° C., 15 to 20 g of γ-aminopropyltriethoxysilane is added dropwise to the aqueous polyurethane main chain emulsion at a rate of 0.5 to 0.8 g / min, and stirred to initially graft the silane monomer to the main chain to obtain a primary grafted emulsion; Adding 0.5-1 g of an organic tin catalyst to the primary grafting emulsion, so that the silane grafting rate reaches 60-70% as measured by infrared spectroscopy, to obtain a catalytic grafting emulsion; 5-8 g of vinyltrimethoxysilane was added dropwise to the catalytic grafting emulsion at a rate of 0.3 g / min, and the silicon content was determined to be 1.5-2.5 wt % by elemental analysis to obtain a grafted modified polyurethane emulsion.

[0048] In this embodiment, the aqueous polyurethane main chain emulsion is heated to 70°C, and 15-20g of γ-aminopropyltriethoxysilane (APTES) is added dropwise at a rate of 0.5-0.8g / min at this temperature. At this stage, the silane monomer reacts with the isocyanate group in the aqueous polyurethane molecule through its aminopropyl group and begins to be grafted onto the polyurethane main chain. The selection of γ-aminopropyltriethoxysilane is because it can react with the isocyanate group through its amino group (-NH2) to form a covalent bond, and graft the silane monomer onto the polyurethane molecular chain, thereby improving the crosslinking degree and chemical resistance of the polyurethane. Stirring is to ensure that the silane monomer is evenly distributed and reacts with the polymer chain in the polyurethane emulsion. The reaction time is about 3 hours to ensure the sufficiency of the grafting reaction. After this stage, a primary grafting emulsion is obtained, and 0.5-1g of an organotin catalyst is added to the primary grafting emulsion. By using an organotin catalyst, the further grafting reaction of the silane monomer with the polyurethane main chain can be effectively promoted. At this time, the reaction system was stirred at a rate of 500 rpm to ensure the uniformity of the reaction. At this stage, the silane grafting rate was monitored by infrared spectroscopy, with the goal of achieving a grafting rate of 60-70%. Infrared spectroscopy determines the degree of grafting by detecting the characteristic peak of siloxane (appearing at a wave number of about 1100 cm^-1). When the silane grafting rate reached the desired level, 5-8 g of vinyl trimethoxy silane was added and dripped into the catalytic grafting emulsion at a rate of 0.3 g / min. The addition of vinyl trimethoxy silane is mainly to introduce vinyl functional groups, which can further enhance the crosslinking and heat resistance of polyurethane, and also improve its compatibility with other materials. The rate of dripping vinyl trimethoxy silane was controlled at 0.3 g / min. After the reaction was completed, elemental analysis was used to determine the silicon content, and the target silicon content should be 1.5-2.5 wt%. Through this detection method, the silane content in the grafted modified polyurethane emulsion can be accurately evaluated, thereby ensuring that the grafting modification effect has achieved the expected goal. Through the entire silane grafting modification treatment, the obtained grafted modified polyurethane emulsion has significantly improved performance. For example, by using nuclear magnetic resonance spectroscopy (NMR) technology to analyze the grafted product, it can be confirmed that the characteristic peaks of siloxane are generated, proving that silane has been successfully grafted onto the polyurethane molecular chain. Further centrifugation tests showed that the emulsion had good stability and no stratification, indicating that the grafting reaction had no negative impact on the dispersibility of the emulsion. In addition, through infrared spectroscopy and elemental analysis, the silicon content of the obtained grafted modified polyurethane emulsion was 1.5-2.5wt%, and the grafting rate reached more than 85%, showing the high efficiency of the silane grafting reaction.

[0049] In one embodiment, the step of purifying the grafted modified polyurethane emulsion to obtain a finished waterborne polyurethane polymer material comprises: Adding 3-5 g of a polyether-modified siloxane defoamer and 2-4 g of a hydroxyethyl cellulose thickener to the graft-modified polyurethane emulsion to obtain a pre-adjusted emulsion; The pre-adjusted emulsion is mixed with a sodium hydroxide solution, and the pH value is adjusted to 7.0-7.5 to obtain a neutralized emulsion; Under the conditions of vacuum degree of 0.07-0.09 MPa and temperature of 45-55° C., the neutralized emulsion is subjected to reduced pressure distillation treatment until the acetone content in the neutralized emulsion is less than 0.1%, thereby obtaining a finished waterborne polyurethane polymer material.

[0050] In this embodiment, 3-5 g of polyether-modified siloxane defoamer and 2-4 g of hydroxyethyl cellulose thickener are added, and then stirred at a stirring speed of 300 rpm for 30 minutes to ensure that the defoamer and thickener can be evenly dispersed in the emulsion to achieve the desired effect. The pre-adjusted emulsion is mixed with a sodium hydroxide solution, and the pH value is adjusted to a range of 7.0-7.5 to eliminate acidic substances that may exist in the emulsion and ensure the chemical stability of the aqueous polyurethane emulsion. The vacuum distillation treatment is carried out under the conditions of a vacuum degree of 0.07-0.09 MPa and a temperature of 45-55 ° C. The principle of vacuum distillation is to use the fact that the boiling point of the solvent will decrease under a low pressure environment, so that the solvent can evaporate and be removed at a lower temperature. At this time, acetone is volatilized from the emulsion and collected by a condensation system to ensure that the content of acetone in the emulsion is reduced to less than 0.1%. This process can effectively remove most of the acetone, reduce the impact of residual solvents on product quality, and improve the environmental protection and safety of the finished aqueous polyurethane. After the vacuum distillation treatment is completed, the acetone content in the emulsion is tested by gas chromatography to ensure that the residual acetone content meets the standard and is less than 0.1%. Gas chromatography is an accurate analytical method that can effectively detect the content of components in complex mixtures. In this case, it is used to confirm whether the residual acetone meets the requirements. Finally, the acetone content in the waterborne polyurethane emulsion after this purification step is less than 0.1%, proving the effectiveness of this step. The solid content of the obtained waterborne polyurethane polymer material is determined by the drying method, and the measured solid content is between 40 and 45%. By accurately controlling the solid content, it can be ensured that the waterborne polyurethane material has good application performance and can meet the needs of different industrial fields.

[0051] The present invention also discloses a waterborne polyurethane polymer material, which is prepared by the preparation method of the waterborne polyurethane polymer material as described in any one of the above items, wherein the polyurethane main chain is composed of a terminal hydroxyl polyether prepolymer, a carboxyl-containing modified prepolymer, a chain extender and a silane grafted modified substance; a hydrophilic modified monomer is used to improve the hydrophilicity and dispersibility of the polyurethane; and the silane grafted substance is used to improve the water resistance and wear resistance of the polyurethane; wherein, calculated by mass ratio, in the waterborne polyurethane polymer material, the hydrophilic modified monomer accounts for 7% to 10%, the silane grafted substance accounts for 2% to 5%, and the rest is the polyurethane main chain.

[0052] In the present embodiment, the polyurethane backbone is prepared on the basis of a hydroxyl-terminated polyether prepolymer, which is generated by a polyetherification reaction and an isocyanate reaction, and has a terminal hydroxyl group, which provides a reaction site for subsequent chemical reactions, making the synthesis of polyurethane more controllable. These hydroxyl-terminated polyether prepolymers will react with a carboxyl-modified prepolymer in the next step to form a polyurethane material with high hydrophilicity. The carboxyl-modified prepolymer improves the water solubility and dispersibility of polyurethane by reacting with a hydrophilic monomer, so that water-based polyurethane can maintain good stability in water and is easier to process in practical applications.

[0053] In another embodiment, the waterborne polyurethane polymer material includes: a polyurethane main chain: accounting for 40% to 60%, composed of a terminal hydroxyl polyether prepolymer, a carboxyl-modified prepolymer, a chain extender and a silane-grafted modified substance; water: accounting for 25% to 35%, serving as a dispersion medium in the emulsion; hydrophilic modified monomers (such as dimethylolpropionic acid, etc.): accounting for 3% to 7%, used to improve the hydrophilicity and dispersibility of the polyurethane; silane-grafted substances (such as γ-aminopropyltriethoxysilane, vinyltrimethoxysilane, etc.): accounting for 2% to 5%, used to improve the water resistance, wear resistance and other properties of the polyurethane; stabilizers and additives (such as defoamers, thickeners, etc.): accounting for 0.5% to 2%, used to adjust the stability of the emulsion and improve the performance.

[0054] It is worth noting that the polyethanol raw material and isocyanate in this embodiment are present as a solution only as an example. In actual applications, other suitable raw materials and solvents can be selected for reaction as needed, as long as it can ensure that the final waterborne polyurethane polymer material has the required properties. For example, polyester polyol can be used instead of polyethanol raw material, or organic solvents such as dimethylformamide can be used as reaction medium.

[0055] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a waterborne polyurethane polymer material, characterized in that: include: The polyethanol raw material and isocyanate are mixed and subjected to a prepolymerization reaction to obtain a hydroxyl-terminated polyether prepolymer; Performing hydrophilic modification on the hydroxyl-terminated polyether prepolymer to obtain a carboxyl-modified prepolymer, wherein the grafting rate of the carboxyl-modified prepolymer is greater than 90%; The carboxyl-modified prepolymer is subjected to neutralization and dispersion treatment to obtain an ionic prepolymer emulsion, wherein the average particle size of the ionic prepolymer emulsion is 85-100 nm; The ionic prepolymer emulsion is subjected to a chain extension reaction treatment to obtain an aqueous polyurethane main chain emulsion; The aqueous polyurethane main chain emulsion is subjected to silane grafting modification treatment to obtain a grafted modified polyurethane emulsion; The grafted modified polyurethane emulsion is purified to obtain a finished waterborne polyurethane polymer material.

2. The method for preparing an aqueous polyurethane polymer material according to claim 1, characterized in that: The polyethanol raw material is any one or a combination of polyethylene glycol, polypropylene glycol, polytetrahydrofuran diol or polyethylene glycol.

3. The method for preparing the waterborne polyurethane polymer material according to claim 1, characterized in that: The isocyanate is any one of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate or hexamethylene diisocyanate or a combination of several of them.

4. The method for preparing the waterborne polyurethane polymer material according to claim 1, characterized in that: The step of mixing the polyethanol raw material and the isocyanate for prepolymerization to obtain a hydroxyl-terminated polyether prepolymer comprises: Put polyethylene glycol with a molecular weight of 800-900 in a reaction container, add dibutyltin dilaurate catalyst accounting for 0.2-0.5% of the weight of polyethylene glycol, heat to 75-80°C under nitrogen protection, stir at a speed of 200-250rpm, and continue to treat for 30-40 minutes to obtain activated polyether polyol; The activated polyether polyol and isophorone diisocyanate are mixed in a mass ratio of 4 to 5:1, and premixed under low-speed stirring at 50 to 60° C. to obtain a primary mixture; The primary mixture is placed in a reaction kettle, and isophorone diisocyanate is slowly added dropwise at a dropping speed of 0.8-1.2 g / min and the reaction temperature is maintained at 80-85° C. to obtain a semi-reacted prepolymer; Applying a slight positive pressure of 0.02-0.05 MPa to the semi-reacted prepolymer in the reactor, heating it to 85-90° C., and introducing low-flow nitrogen to adjust the gas phase equilibrium to obtain a refined prepolymer; The refined prepolymer is mixed with a difunctional polyether amine, and stirred for reaction at 75-80° C. to obtain a hydroxyl-terminated polyether prepolymer, wherein the mass ratio of the refined prepolymer to the difunctional polyether amine is 99:1-99.5:0.

5.

5. The method for preparing the waterborne polyurethane polymer material according to claim 1, characterized in that: The step of subjecting the hydroxyl-terminated polyether prepolymer to hydrophilic modification to obtain a carboxyl-modified prepolymer, wherein the grafting rate of the carboxyl-modified prepolymer is greater than 90%, comprises: Placing the hydroxyl-terminated polyether prepolymer in a cooling device, cooling it to 45-50° C., and maintaining the constant temperature for 30 minutes to obtain a low-temperature prepolymer matrix; Add 30-35 g of dimethylol propionic acid and 40-50 mL of acetone into the low-temperature prepolymer matrix and mix to obtain a monomer mixed prepolymer; The monomer-mixed prepolymer is heated to 65-70° C. in a nitrogen environment, and 0.5-1 g of triethylamine is added as a catalyst, stirred at 500 rpm for 15 minutes, and reacted at 70° C. for 1 hour to obtain a catalytically modified prepolymer; The catalytic modified prepolymer is heated to 75-80° C., 5-10 mL of N,N-dimethylformamide is added as a cosolvent, and the change of the characteristic peak of the carboxyl group in the monomer mixed prepolymer at 1710 cm⁻¹ is monitored by Fourier transform infrared spectroscopy. When the intensity of the characteristic peak of the carboxyl group reaches a preset value, heating is stopped to obtain a carboxyl-containing modified prepolymer, wherein the preset value is that the intensity of the characteristic peak of the carboxyl group reaches more than 95% of the initial characteristic peak intensity of the carboxyl group in the monomer mixed prepolymer.

6. The method for preparing the waterborne polyurethane polymer material according to claim 1, characterized in that: The step of neutralizing and dispersing the carboxyl-modified prepolymer to obtain an ionic prepolymer emulsion, wherein the average particle size of the ionic prepolymer emulsion is 85 to 100 nm, comprises: Cooling the carboxyl-modified prepolymer to 35-40° C. at a cooling rate of 5° C. / min to obtain a low-temperature carboxyl-modified prepolymer; Adding 10-15 g of triethylamine as a neutralizing agent to the low-temperature carboxyl-containing prepolymer and stirring, and determining the degree of neutralization by acid-base titration to reach 93-97%, thereby obtaining a neutralized prepolymer; Slowly adding 50-70 mL of deionized water to the neutralized prepolymer for low-speed dispersion treatment, controlling the water addition speed to 1-2 mL / min, to obtain a primary dispersion; 5-10 g of acetone was added to the primary dispersion to dilute it so that the solid content was controlled at 35-40%. The adjusted dispersion was placed in a constant temperature still box and kept at a constant temperature of 25-30° C. for 2-3 hours to obtain an ionic prepolymer emulsion with an average particle size of 85-100 nm.

7. The method for preparing the waterborne polyurethane polymer material according to claim 1, characterized in that: The step of subjecting the ionic prepolymer emulsion to a chain extension reaction to obtain an aqueous polyurethane main chain emulsion comprises: The ionic prepolymer emulsion is heated to 55-65° C. and maintained for 30 minutes to allow the ion clusters in the emulsion to fully dissociate, and 8-12 g of ethylenediamine is added dropwise at a rate of 0.4-0.6 g / min as a first chain extender to initially extend the molecular chain to obtain a primary chain extension emulsion; Add 5-10 g of hydroxyl-containing polyether polyol to the primary chain extension emulsion, maintain the temperature at 60-70° C. for reaction for 1 hour, stabilize the viscosity of the system at 400-500 mPa·s, and obtain a steady-state chain extension emulsion; 3-5 g of diaminobutylene as a second chain extender is added dropwise to the stable chain extension emulsion at a rate of 0.3-0.5 g / min to further graft and extend the molecular chain to obtain the waterborne polyurethane main chain emulsion.

8. The method for preparing the waterborne polyurethane polymer material according to claim 1, characterized in that: The step of subjecting the aqueous polyurethane main chain emulsion to silane grafting modification to obtain a grafted modified polyurethane emulsion comprises: At 70° C., 15 to 20 g of γ-aminopropyltriethoxysilane is added dropwise to the aqueous polyurethane main chain emulsion at a rate of 0.5 to 0.8 g / min, and stirred to initially graft the silane monomer to the main chain to obtain a primary grafted emulsion; Adding 0.5-1 g of an organic tin catalyst to the primary grafting emulsion, so that the silane grafting rate reaches 60-70% as measured by infrared spectroscopy, to obtain a catalytic grafting emulsion; 5-8 g of vinyltrimethoxysilane was added dropwise to the catalytic grafting emulsion at a rate of 0.3 g / min, and the silicon content was determined to be 1.5-2.5 wt % by elemental analysis to obtain a grafted modified polyurethane emulsion.

9. The method for preparing the waterborne polyurethane polymer material according to claim 1, characterized in that: The step of purifying the grafted modified polyurethane emulsion to obtain a finished waterborne polyurethane polymer material comprises: Adding 3-5 g of a polyether-modified siloxane defoamer and 2-4 g of a hydroxyethyl cellulose thickener to the graft-modified polyurethane emulsion to obtain a pre-adjusted emulsion; The pre-adjusted emulsion is mixed with a sodium hydroxide solution, and the pH value is adjusted to 7.0-7.5 to obtain a neutralized emulsion; Under the conditions of vacuum degree of 0.07-0.09 MPa and temperature of 45-55° C., the neutralized emulsion is subjected to reduced pressure distillation treatment until the acetone content in the neutralized emulsion is less than 0.1%, thereby obtaining a finished waterborne polyurethane polymer material.

10. A waterborne polyurethane polymer material, characterized in that: The waterborne polyurethane polymer material is prepared by the preparation method of any one of claims 1 to 9, wherein the waterborne polyurethane polymer material comprises: The polyurethane main chain is composed of a terminal hydroxyl polyether prepolymer, a carboxyl-modified prepolymer, a chain extender and a silane-grafted modified substance; a hydrophilic modified monomer is used to improve the hydrophilicity and dispersibility of the polyurethane; and a silane-grafted substance is used to improve the water resistance and wear resistance of the polyurethane; wherein, calculated by mass ratio, in the waterborne polyurethane polymer material, the hydrophilic modified monomer accounts for 7% to 10%, the silane-grafted substance accounts for 2% to 5%, and the rest is the polyurethane main chain.

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