A silicon-modified waterborne polyurethane and its preparation method

Abstract

This application provides a silicone-modified waterborne polyurethane and its preparation method. The preparation method includes the following steps: Hydroxyl-terminated polyether-modified silicone oil and isoflurane diisocyanate are placed in a container, and the temperature is raised to 80-90℃ and maintained for 1.5-2.5 hours; then polytetrahydrofuran and diphenylsilanediol are added sequentially, and the temperature is raised to 85-95℃ and reacted for 2.5-3.5 hours until the -NCO content is close to or reaches the theoretical value, at which point the reaction is stopped to obtain a prepolymer; then the temperature of the prepolymer is lowered to below 40℃, acetone and triethylamine are added, and the reaction is carried out for 3-5 minutes; then the product is transferred to a reaction vessel containing an appropriate amount of deionized water and defoamer and stirred evenly to form an emulsion; finally, a mixture of deionized water, diethylenetriamine, and ethylenediamine is added for emulsification to obtain the silicone-modified waterborne polyurethane.

Description

Technical Field

[0001] This application relates to the field of new materials technology, and in particular to a silicon-modified waterborne polyurethane and its preparation method. Background Technology

[0002] Waterborne polyurethane (WPU) is synthesized using water as the solvent instead of organic solvents as the dispersion medium for polyurethane resins. Compared with ordinary polyurethane, waterborne polyurethane has advantages such as lower toxicity, lower energy consumption, environmental friendliness, and better overall performance. Due to these advantages, it is widely used in industrial production such as coatings and adhesives. Bayer was the first to use waterborne polyurethane resin as a coating agent in leather materials, and it gradually became an important commodity. Through extensive research on its performance, waterborne polyurethane has made remarkable progress in industrial applications despite its relatively short development history. With the country's vigorous efforts to control industrial pollution and the increasing need for environmental health and safety, significant resources have been invested in modified resins. Today, waterborne polyurethane production occupies a pivotal position in the polyurethane industry.

[0003] Hydrophobic modifiers for waterborne polyurethanes are typically organofluorine modified, organosilicon modified, and vegetable oil modified (Du Y, Yang Z, Zhou C. Study on waterborne polyurethanes based on poly(dimethylsiloxane) and perfluorinated polyether[J]. Macromolecular Research, 2015, 23(9):867-875). Li Peizhi et al. (Li Peizhi, Shen Yiding, Yang Xiaowu. Study on surface properties of cationic perfluoroalkyl waterborne polyurethane coatings[J]. Functional Materials, 2011, 42(04):632-634+638) modified waterborne polyurethanes with organofluorine. The mechanical properties of the resin were improved after modification. However, fluorine compounds are highly polluting to the environment, difficult to degrade, and highly toxic, which is extremely unfriendly to the ecosystem and detrimental to sustainable development. Therefore, fluorine-modified waterborne polyurethanes have great limitations. Developing non-toxic and hydrophobic polyurethanes is an important goal. Organosilicon-modified waterborne polyurethane has significant effects and is safe and environmentally friendly. The silicon-oxygen bonds present in the molecular chain of hydroxyl silicone oil have bond energy, high polarity, good softness, and a shielding effect on the attached hydroxyl groups (Deng Shengji, Wang Xiangmei. Research progress on crosslinking-modified waterborne polyurethane [J]. Polyurethane Industry, 2010, 25(4):9-12). Because of these advantages, adding organosilicon to modify waterborne polyurethane can make the resin better preserved. Because the use of organosilicon materials for modification is cost-effective and has the characteristics of being pollution-free, organosilicon-modified resin has become a hot topic. In laboratory and factory production, when modifying waterborne polyurethane, the crosslinking method is usually used to introduce hydrophobic groups into the molecular chain segments of waterborne polyurethane. Moreover, organosilicon materials are relatively inexpensive. Therefore, in the process of synthesizing waterborne polyurethane, the introduction of organosilicon to replace some soft segments of waterborne polyurethane can effectively modify waterborne polyurethane and achieve the purpose of improving its hydrophobic properties and other important properties. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned problems by providing a silicon-modified waterborne polyurethane and its preparation method.

[0005] The technical solution of this application is implemented as follows: This invention provides a method for preparing silicone-modified waterborne polyurethane, comprising the following steps: Bis-hydroxyl-terminated polyether modified silicone oil and isoflavone diisocyanate are placed in a container and the temperature is raised to 80-90℃ and maintained for 1.5-2.5 hours. Then, polytetrahydrofuran and diphenylsilanediol are added in sequence, and the temperature is raised to 85-95℃ and reacted for 2.5-3.5 hours until the -NCO value is close to or reaches the theoretical value, at which point the reaction is stopped to obtain a prepolymer. Then, the temperature of the prepolymer is lowered to below 40℃, acetone and triethylamine are added, and the reaction is carried out for 3-5 minutes. The product is then transferred to a reaction vessel containing an appropriate amount of deionized water and defoamer and stirred evenly to form an emulsion. Finally, a mixture of deionized water, diethylenetriamine and ethylenediamine is added for emulsification to obtain silicone-modified waterborne polyurethane.

[0006] When diethylenetriamine (DETA, trifunctional) is used alone as a chain extender, although it can form a three-dimensional urea bond crosslinking network (improving hardness and water resistance), excessively high crosslinking density will lead to brittle film, reduced elongation, and a sharp increase in emulsion viscosity, which is not conducive to processing.

[0007] While using ethylenediamine (EDA, difunctional) alone can linearly extend the chain to increase the molecular weight, insufficient cross-linking leads to poor water resistance, tensile strength and storage stability.

[0008] This invention creatively utilizes the synergistic effect of DETA and EDA: by combining trifunctional DETA (providing crosslinking sites) and difunctional EDA (providing linear chain growth), moderate crosslinking is achieved, ensuring the formation of a crosslinked network (improving water resistance and strength) while avoiding the brittleness and high viscosity caused by excessive crosslinking, thus obtaining moderate flexibility and processing flowability. Furthermore, polyfunctional amines (such as DETA) are highly reactive and tend to react rapidly with the -NCO terminal of the prepolymer during post-chain extension, leading to gelation and emulsification failure. In this invention, the combined use of DETA and EDA results in a milder reaction than using high-functionality amines alone, reducing the likelihood of gelation; simultaneously, the pre-neutralization of TEA into a salt reduces the reactivity of the prepolymer, ensuring controllable chain extension below 40°C and a stable emulsion formation process. Furthermore, the use of diphenylsilanediol is to regulate the prepolymerization reaction. It needs to be added later to extend the reaction time or as a catalyst. Diphenylsilanediol mainly enters the soft segment region (competing with polyether / polyester polyol for -NCO), making the long chain less prone to hydrolysis and self-polymerization (fewer end groups, stable main chain), and the system is more stable.

[0009] As a further improvement, for every 50 parts by weight of isoflavone diisocyanate, 5 to 40 parts by weight of hydroxyl-terminated polyether modified silicone oil, 8 to 9 parts by weight of diphenylsilanediol, 100 to 160 parts by weight of polytetrahydrofuran, 6 to 7 parts by weight of triethylamine, 2 to 3 parts by weight of diethylenetriamine, 2 to 3 parts by weight of ethylenediamine, and 630 to 650 parts by weight of water.

[0010] As a further improvement, for every 50 parts by weight of isoflavone diisocyanate, 10-30 parts by weight of hydroxyl-terminated polyether modified silicone oil, 8.6-8.8 parts by weight of diphenylsilanediol, 120-140 parts by weight of polytetrahydrofuran, 6.5-6.6 parts by weight of triethylamine, 2.5-2.7 parts by weight of diethylenetriamine, 2.2-2.4 parts by weight of ethylenediamine, and 635-645 parts by weight of water are used.

[0011] As a further improvement, the specific steps for detecting NCO include: Weigh a small amount of the sample to be tested and record its mass as m (unit: g). Then add it to the conical flask used for titration. Dissolve the sample in the conical flask with di-n-butylamine, dilute with acetone solvent, and add bromothymol blue indicator after uniform dilution. Titrate with hydrochloric acid solution of known concentration c (unit: mol / L) until the solution color changes from blue to yellow. If the color does not fade within 30 seconds, the titration endpoint has been reached. Record the volume of hydrochloric acid consumed as V1 (unit: ml). Set up a blank group for detection and correction. Record the hydrochloric acid consumed for correction as V2 (unit: ml). The NCO content is calculated as shown in the following formula.

[0012] .

[0013] As a further improvement, the method involves placing the hydroxyl-terminated polyether-modified silicone oil and isoflurane diisocyanate into a container, raising the temperature to 80-90°C and maintaining the reaction for 1.5-2.5 hours; then sequentially adding polytetrahydrofuran and diphenylsilanediol, raising the temperature to 85-95°C and reacting for 2.5-3.5 hours, until the -NCO content approaches or reaches the theoretical value, at which point the reaction is stopped to obtain the prepolymer. Specifically, this includes: The hydroxyl-terminated polyether modified silicone oil and isoflurane diisocyanate were placed in a container and the temperature was raised to 83~96℃ and the reaction was maintained for 1.8~2.2h; then polytetrahydrofuran and diphenylsilanediol were added in sequence, and the temperature was raised to 88~92℃ and the reaction was maintained for 2.8~3.2h.

[0014] The present invention further provides a silicon-modified waterborne polyurethane, wherein the silicon-modified waterborne polyurethane is obtained by the above method.

[0015] The advantages or beneficial effects of the above technical solutions include at least the following: The silicon-modified waterborne polyurethane provided by this invention has an infrared spectrum at 1240 cm⁻¹. -1 1060cm -1 and 805cm -1 Characteristic peaks containing silicon functional groups appeared at all locations, such as 805 cm⁻¹. -1 The characteristic peaks of the Si-CH3 functional group confirm the successful preparation of silicon-modified waterborne polyurethane in this experiment. During the experiment, different amounts of organosilicon were added to introduce hydrophobic groups, thereby altering its properties. Furthermore, experimental results show that by adding organosilicon, the hydrophobicity of the waterborne polyurethane decreased from 15.47% without Si to 5.41%, significantly improving its hydrophobicity. Simultaneously, the introduction of hydroxyl silicone oil increased the flexibility and tensile strength of the polyurethane film, resulting in a significant improvement in mechanical properties. Further testing and analysis demonstrate that the method used in this experiment, which modifies waterborne polyurethane with organosilicon, produces an emulsion with good stability, allowing for stable storage and effectively achieving the experimental objectives. Attached Figure Description

[0016] The accompanying drawings illustrate exemplary embodiments of the present application and, together with the description thereof, serve to explain the principles of the present application. These drawings are included to provide a further understanding of the present application and are incorporated in and constitute a part of this specification.

[0017] Figure 1 A flowchart of the preparation method of silicon-modified waterborne polyurethane provided in an embodiment of the present invention is shown.

[0018] Figure 2A flowchart of the preparation method of the silicon-modified waterborne polyurethane provided in the comparative example of the present invention is shown.

[0019] Figure 3 The infrared spectrum of the silicon-modified waterborne polyurethane provided in the embodiments of the present invention is shown. Detailed Implementation

[0020] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While some embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this application. It should be understood that the drawings and embodiments of this application are for illustrative purposes only and are not intended to limit the scope of protection of this application.

[0021] It should be noted that, where there is no conflict, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] The names of the messages or information exchanged between multiple devices in the embodiments of this application are for illustrative purposes only and are not intended to limit the scope of these messages or information.

[0023] I. Experimental Reagents and Instruments Table 1. Reagents used in the experiment

[0024] Table 2. Instruments used in the experiment

[0025] II. Example: As shown in Table 3, weigh the reagents, and place the hydroxyl-terminated polyether modified silicone oil and isoflavone diisocyanate (IPDI) into a 500ml open-top four-necked flask equipped with a thermometer and a mechanical stirrer. Raise the temperature to 85℃ and maintain the reaction for 2 hours. Then, add polytetrahydrofuran (PTMEG) sequentially, followed by slow dropwise addition of diphenylsilanediol, and raise the temperature to 90℃ for 3 hours. Sampling is performed using di-n-butylamine dissolved in acetone and titrated with hydrochloric acid to determine if the -NCO content is close to or reaches the theoretical value. If it is too high, continue the reaction; if it is close to or reaches the theoretical value, the prepolymer can be obtained. The prepolymer solution temperature was lowered to below 40℃, and acetone and triethylamine (TEA) were added as shown in Table 3. The reaction was allowed to proceed for 3-5 minutes. The product was then transferred to a double-boiler containing appropriate amounts of deionized water and defoamer and stirred for 5 minutes. Finally, a mixture of deionized water, diethylenetriamine (DETA), and ethylenediamine (EDA) was added and emulsified for 10 minutes to obtain the silicone-modified waterborne polyurethane emulsion. The synthesis process is as follows: Figure 1 As shown.

[0026] Table 3 shows the amount of raw materials used in the synthesis of silicon-modified waterborne polyurethane.

[0027] Note: (-NCO) / (-OH) are both 1.6, that is, the R value is 1.6.

[0028] III. Comparative Examples: Comparative Example 1: As shown in Table 3, weigh the reagents, add the hydroxyl-terminated polyether modified silicone oil and isoflavone diisocyanate (IPDI) to a 500ml open-top four-necked flask equipped with a thermometer and a mechanical stirrer, and raise the temperature to 85℃ and maintain the reaction for 2 hours. Then, add polytetrahydrofuran (PTMEG) sequentially and raise the temperature to 90℃ and react for 3 hours. Take a sample and use the di-n-butylamine dissolved in acetone and titrated with hydrochloric acid to detect whether the -NCO is close to or reaches the theoretical value. If it is too high, continue the reaction; if it is close to or reaches the theoretical value, stop the reaction to obtain the prepolymer. Then, lower the temperature of the synthesized product to below 40℃, add acetone and triethylamine (TEA), and react for 3-5 minutes. Then, transfer the product to a double-sided container containing an appropriate amount of deionized water and defoamer and stir until it is homogeneous into an emulsion. Finally, add a mixture of deionized water, diethylenetriamine (DETA), and ethylenediamine (EDA) to emulsify, and the waterborne polyurethane emulsion is obtained. The synthesis process is as follows: Figure 2 As shown.

[0029] Comparative Example 2: The process is basically the same as in Example 1, except that: a mixture of deionized water and ethylenediamine (EDA) is added at the end for emulsification to obtain an aqueous polyurethane emulsion.

[0030] Comparative Example 3: The process is basically the same as in Example 1, except that: a mixture of deionized water and diethylenetriamine (DETA) is added at the end for emulsification to obtain an aqueous polyurethane emulsion.

[0031] IV. Performance Characterization and Testing 4.1 Determination of -NCO content in prepolymer

[0032] Weigh a small amount of the sample to be tested and record its mass as m (unit: g). Add this to the conical flask used for titration. Dissolve the sample in the conical flask using di-n-butylamine, dilute with acetone, and after thorough dilution, add the indicator (bromothymol blue). Titrate with a hydrochloric acid solution of known concentration c (unit: mol / L) until the solution color changes from blue to yellow. If the color does not fade within 30 seconds, the titration endpoint has been reached. Record the volume of hydrochloric acid consumed as V1 (unit: ml). Set up a blank control group for calibration; record the hydrochloric acid consumed during calibration as V2 (unit: ml). The NCO content is calculated as shown in the following formula.

[0033] .

[0034] 4.2 Preparation of Silicon-Modified Waterborne Polyurethane Film (1) Preparation of infrared test film: The synthesized emulsion was placed in a rotary evaporator to evaporate the acetone solvent; a small amount of emulsion was scraped onto release paper and dried in an oven at about 120°C for 5 minutes. The film was then removed and dried for 1 hour for later use.

[0035] (2) Mechanical property test film preparation: The synthesized emulsion was placed in a rotary evaporator to evaporate the acetone solvent; 150g of the desolventized emulsion was taken and added to 1-2 tubes of defoamer and about 3g of leveling agent. The mixture was stirred to make it evenly mixed. Then, an appropriate amount of thickener was added to adjust the viscosity to 4000-6000mPa·s. Finally, the compounded emulsion was scraped onto the release paper and dried in an oven at about 120℃ for 5min.

[0036] 4.3 Infrared Spectroscopy Test of Adhesive Film The synthesized emulsion was characterized using a Nicolet IS10 Fourier transform infrared spectrometer (FTIR) from the United States. After the emulsion was fabricated into a film using a film-forming method, the film was analyzed at a scanning range of 4000 cm⁻¹. -1 Up to 500cm -1 Infrared characterization was performed with a resolution of 0.1 cm and 32 scans.

[0037] Figure 3 This is the infrared spectrum of the synthesized sample film. Analysis revealed a stretching vibration peak of -NH at 3330 cm⁻¹ in the spectrum of the WPU polymer. -1 C=O corresponds to 1718cm -1 The stretching vibration peak value was observed. Meanwhile, no isocyanate ions appeared in the FT-IR spectra of these polyesters, indicating that the reaction was complete during synthesis, successfully synthesizing waterborne polyurethane. Furthermore, after modification with dihydroxy organosilicon, the peak value was 1552 cm⁻¹. -1 A C-N absorption peak was observed in the urethane ester; simultaneously, a Si-CH vibrational absorption peak appeared at 1259 cm⁻¹. -1At this point, because the absorption wavenumbers of the two peaks are similar, they easily overlap and are not clearly distinguishable. Meanwhile, the stretching vibration peak of Si—CH3 can be observed in the spectrum: 805 cm⁻¹. -1 This indicates that hydroxyl silicone oil has been successfully grafted onto waterborne polyurethane for modification, resulting in the successful synthesis of a series of silicone-modified waterborne polyurethanes.

[0038] Simultaneously, observing the characteristic peaks of -Si-CH3 and -Si-O-Si- in the spectrum, it can be clearly seen that with the increase of w (organosilicon), the characteristic peaks at 1259 cm⁻¹... -1 805cm -1 1060cm -1 The peak value at that location was significantly enhanced. This also indicates that a series of silicon-modified waterborne polyurethanes were successfully synthesized in this experiment.

[0039] 4.4 Emulsion Viscosity Test Emulsion viscosity testing uses a digital viscometer. The emulsion is placed in a container with a diameter greater than 7 cm. A suitable rotor is selected, and the rotor is inserted into the emulsion for testing and data reading. During the test, the torque should be between 10% and 90% for the data to be accurate.

[0040] 4.5 Emulsion stability test Centrifuge PU and Si-PU emulsions at 3000 r / min for 15 min using an HC-3514 centrifuge and observe whether there is precipitation or stratification. If there is no precipitation or stratification, it indicates that the emulsion is relatively stable and not prone to stratification or deterioration.

[0041] Storage stability is a fundamental indicator for the application of waterborne polyurethane. Table 4 shows that after centrifuging the emulsions at 3000 r / min for 15 min, no precipitation or stratification occurred, indicating good emulsion stability, which is beneficial for long-term storage. Furthermore, the emulsions were generally translucent with a bluish sheen, resulting in an attractive appearance. According to the method specified in GB6753.3-86, the storage stability of the samples was over 6 months, with a solid content of approximately 25%. The viscosity increased with increasing organosilicon content. This is because when the organosilicon content is too high, excessive Si-O bonds during emulsification will hydrolyze and condense, producing cross-linked waterborne polyurethane, thus increasing the emulsion viscosity.

[0042] Table 4 shows the emulsion state, stability, and viscosity data.

[0043] 4.6 Mechanical property testing of the adhesive film Three sets of parallel tensile tests were performed on dumbbell-shaped specimens (18mm×3mm) of the adhesive film using an electronic tensile testing machine.

[0044] Table 5 shows that compared with waterborne polyurethane films without added silicone, the addition of silicone increases the tensile strength and elongation at break of the waterborne polyurethane films. However, with increasing silicone content, the tensile strength and elongation at break decrease. This is because the hydrophilicity of hydroxyl silicone oil reduces the solubility of polyurethane in aqueous solvents after its introduction into waterborne polyurethane, thus altering its mechanical properties. Simultaneously, the large chemical bond energy and high flexibility of hydroxyl silicone oil increase both tensile strength and elongation at break. Excessive addition of hydroxyl silicone oil increases the film's flexibility, leading to a decrease in tensile strength, which further decreases with increasing hydroxyl silicone oil content.

[0045] Table 5 shows the test data for the mechanical properties of the adhesive film.

[0046] 4.7 Water Absorption Rate Test of Adhesive Film Water absorption rate and swelling rate of the adhesive film: Cut the adhesive film into samples with dimensions of 3cm × 3cm, weigh them and record the weight as m1, then soak them in deionized water at room temperature for 24 hours. Remove them, blot the surface moisture with filter paper, and weigh them again and record the weight as m2. The formula for calculating the water absorption rate or swelling rate is shown below: .

[0047] Table 6 shows that after immersion in water for 24 hours, the water absorption rate of the film decreased with increasing organosilicon content. The data indicates that adding organosilicon segments to replace some soft segments of the molecular chain during the synthesis of waterborne polyurethane improves the hydrophobicity of the film. Upon contact with water, organosilicon migrates and accumulates on the film surface, forming a hydrophobic layer that effectively reduces water absorption, thus making the film waterproof in a short time. Experimental data shows that the water absorption rate of the modified film decreased significantly from 15.47% without added organosilicon to 5.43% with an added organosilicon content of 13.5%. Therefore, adding a certain amount of organosilicon to modify the waterborne polyurethane film provides excellent hydrophobic and waterproof effects. However, when the silicon content continues to increase to a certain value, the water absorption rate hardly changes, indicating that the organosilicon may have migrated and accumulated to the film surface to a saturated state. Therefore, in this experiment, adding 30g of organosilicon was the optimal amount.

[0048] Table 6 shows the water absorption rate of the film after soaking in deionized water for 24 hours.

[0049] Those skilled in the art should understand that the above embodiments are merely for illustrative purposes and are not intended to limit the scope of this application. Those skilled in the art can make other changes or modifications based on the above disclosure, and these changes or modifications still fall within the scope of this application.

Claims

1. A method for preparing silicon-modified waterborne polyurethane, characterized in that, Includes the following steps: Bis-hydroxyl-terminated polyether modified silicone oil and isoflavone diisocyanate are placed in a container and the temperature is raised to 80-90℃ and maintained for 1.5-2.5 hours. Then, polytetrahydrofuran and diphenylsilanediol are added slowly in sequence, and the temperature is raised to 85-95℃ and reacted for 2.5-3.5 hours until the -NCO value is close to or reaches the theoretical value, at which point the reaction is stopped to obtain a prepolymer. Then, the temperature of the prepolymer is lowered to below 40℃, acetone and triethylamine are added, and the reaction is carried out for 3-5 minutes. The product is then transferred to a reaction vessel containing an appropriate amount of deionized water and defoamer and stirred evenly to form an emulsion. Finally, a mixture of deionized water, diethylenetriamine and ethylenediamine is added for emulsification to obtain silicone-modified waterborne polyurethane.

2. The method for preparing silicon-modified waterborne polyurethane according to claim 1, characterized in that: For every 50 parts by weight of isoflavone diisocyanate, use 5-40 parts by weight of hydroxyl-terminated polyether modified silicone oil, 8-9 parts by weight of diphenylsilanediol, 100-160 parts by weight of polytetrahydrofuran, 6-7 parts by weight of triethylamine, 2-3 parts by weight of diethylenetriamine, 2-3 parts by weight of ethylenediamine, and 630-650 parts by weight of water.

3. The method for preparing silicon-modified waterborne polyurethane according to claim 1, characterized in that: For every 50 parts by weight of isoflavone diisocyanate, use 10-30 parts by weight of hydroxyl-terminated polyether modified silicone oil, 8.6-8.8 parts by weight of diphenylsilanediol, 120-140 parts by weight of polytetrahydrofuran, 6.5-6.6 parts by weight of triethylamine, 2.5-2.7 parts by weight of diethylenetriamine, 2.2-2.4 parts by weight of ethylenediamine, and 635-645 parts by weight of water.

4. The method for preparing silicon-modified waterborne polyurethane according to claim 1, characterized in that: The specific steps for detecting NCO include: Weigh a small amount of the sample to be tested and record its mass as m (unit: g). Then add it to the conical flask used for titration. Dissolve the sample in the conical flask with di-n-butylamine, dilute with acetone solvent, and add bromothymol blue indicator after uniform dilution. Titrate with hydrochloric acid solution of known concentration c (unit: mol / L) until the solution color changes from blue to yellow. If the color does not fade within 30 seconds, the titration endpoint has been reached. Record the volume of hydrochloric acid consumed as V1 (unit: ml). Set up a blank group for detection and correction. Record the hydrochloric acid consumed for correction as V2 (unit: ml). The NCO content is calculated as shown in the following formula. 。 5. The method for preparing silicon-modified waterborne polyurethane according to claim 1, characterized in that: The process involves placing hydroxyl-terminated polyether-modified silicone oil and isoflurane diisocyanate into a container, raising the temperature to 80-90°C and maintaining the reaction for 1.5-2.5 hours; then, polytetrahydrofuran and diphenylsilanediol are added sequentially, and the temperature is raised to 85-95°C for 2.5-3.5 hours. The reaction is stopped when the -NCO level is close to or reaches the theoretical value to obtain the prepolymer. Specifically, this includes: The hydroxyl-terminated polyether modified silicone oil and isoflurane diisocyanate were placed in a container and the temperature was raised to 83~96℃ and the reaction was maintained for 1.8~2.2h; then polytetrahydrofuran and diphenylsilanediol were added in sequence, and the temperature was raised to 88~92℃ and the reaction was maintained for 2.8~3.2h.

6. A silicon-modified waterborne polyurethane, characterized in that: The silicon-modified waterborne polyurethane is obtained by the method described in any one of claims 1-5.

Images