A castor oil-based waterborne polyurethane super-slippery cotton fabric and a preparation method thereof

Abstract

The application provides a castor oil-based waterborne polyurethane super-smooth cotton fabric and a preparation method thereof, and belongs to the technical field of textiles.The preparation method comprises the following steps: mixing aliphatic polyisocyanate and monohydroxyl-terminated polysiloxane, and performing reaction 1 under the condition of heating and stirring; after the reaction 1 is completed, hydrophilic chain extender and castor oil are sequentially added into the reaction system, reaction 2 is performed under the condition of heating and stirring, when the reaction endpoint is reached, the reaction system is cooled, then organic alkali is added, and stirring reaction is performed to obtain a prepolymer; the prepolymer is uniformly dispersed in water, then rotary evaporation is performed to obtain a dispersion; the dispersion is used for pad treatment on a cotton fabric, then solidification is performed to obtain the super-smooth cotton fabric.The super-smooth structure cotton fabric provided by the application has lower adhesion to pollutants, the sliding angle is reduced to about 8 degrees, the service time is longer, and the effect is more prominent.

Description

Technical Field

[0001] This invention relates to the field of textile technology, and in particular to a castor oil-based waterborne polyurethane super-smooth cotton fabric and its preparation method. Background Technology

[0002] Textiles, due to their high flexibility, high specific surface area, and diverse material sources, are widely used in furniture, industrial manufacturing, medical and health care, and agriculture and forestry. However, textiles inevitably come into contact with various substances during use, such as food, oils, and cosmetics. These substances easily adhere to the fabric surface, reducing its aesthetics, comfort, and lifespan. Traditional hydrophobic finished textiles suffer from a decrease in fastness over long-term use. Therefore, developing fabrics with highly efficient super-lubricating properties has become a hot research topic in the textile field today.

[0003] Previous reports on bio-based antifouling coatings have mostly focused on solvent-based polyurethanes using organic solvents. The emission of volatile organic solvents during the curing process poses another environmental hazard. To achieve environmentally friendly polyurethane antifouling coatings, water-based treatment using water as the dispersion medium is one method for improving their environmental friendliness. In the preparation of waterborne polyurethane antifouling coatings, polar hydrophilic groups need to be introduced to disperse the polyurethane in water. However, the presence of these polar hydrophilic groups affects the antifouling performance of the coating. Therefore, modifying waterborne bio-based polyurethane coatings for antifouling performance is extremely challenging. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a castor oil-based waterborne polyurethane super-smooth cotton fabric and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention is a method for preparing castor oil-based waterborne polyurethane super-smooth cotton fabric, comprising the following steps: Aliphatic polyisocyanate and monohydroxy-terminated polysiloxane were mixed and reacted under heating and stirring conditions; After reaction 1 is completed, a hydrophilic chain extender and castor oil are added to the reaction system in sequence, and reaction 2 is carried out under heating and stirring conditions. During the reaction, the reaction endpoint is determined by detecting the content of isocyanate groups -NCO. After the reaction endpoint is reached, the reaction system is cooled down, then an organic base is added, and the reaction is stirred to obtain the prepolymer. The prepolymer was uniformly dispersed in water, and then rotary evaporated to obtain a dispersion. The dispersion is impregnated onto a cotton fabric and then cured to obtain the castor oil-based waterborne polyurethane super-smooth cotton fabric.

[0006] The second technical solution of the present invention is a castor oil-based waterborne polyurethane super-smooth cotton fabric prepared by the above preparation method.

[0007] The present invention discloses the following technical effects: 1. The raw materials required for this invention are inexpensive and readily available, no expensive catalysts are required, and the reaction conditions are mild.

[0008] 2. This invention involves prepolymerizing isocyanates with PDMS chain ends with biomass polyols and hydrophilic chain extenders to form a slightly cross-linked prepolymer network structure. The prepolymer is dispersed in water, and the organic solvent is removed by rotary evaporation to form a stable castor oil-based waterborne polyurethane dispersion. After curing the dispersion, a castor oil-based waterborne polyurethane antifouling coating is obtained, and its sliding angle is tested to reduce to approximately 8°.

[0009] 3. This invention uses bio-based materials, which is environmentally friendly and has a simple production method with mild reaction conditions, making it easy to operate and inexpensive. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 The images are scanning electron microscope (SEM) images of the original cotton fabric and the treated castor oil-based waterborne polyurethane super-smooth cotton fabric from Embodiment 1 of the present invention.

[0012] Figure 2 The infrared spectra of the original cotton fabric and the treated castor oil-based waterborne polyurethane super-smooth cotton fabric in Example 1 of the present invention are shown.

[0013] Figure 3 This is an EDS image of the castor oil-based waterborne polyurethane super-smooth cotton fabric after treatment in Example 1 of the present invention. Detailed Implementation

[0014] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0015] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0016] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0017] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0018] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0019] Inspired by the pitcher plant's structure, which stores liquid substances to form an ultra-smooth surface that prevents contaminant adhesion, this invention utilizes bio-based castor oil to prepare waterborne polyurethane. PDMS segments are used as flexible chains to create an ultra-smooth surface with liquid-like properties. This surface is then applied to cotton fabrics to obtain a fabric with ultra-smooth properties. Compared to traditional superhydrophobic fabrics, this ultra-smooth cotton fabric exhibits lower contaminant adhesion, longer service life, and more pronounced performance.

[0020] The first aspect of this invention provides a method for preparing a castor oil-based waterborne polyurethane super-smooth cotton fabric, comprising the following steps: Aliphatic polyisocyanate and monohydroxy-terminated polysiloxane were mixed and reacted under heating and stirring conditions; After reaction 1 is completed, a hydrophilic chain extender and castor oil are added to the reaction system in sequence, and reaction 2 is carried out under heating and stirring conditions. During the reaction, the reaction endpoint is determined by detecting the content of isocyanate groups -NCO. After the reaction endpoint is reached, the reaction system is cooled down, then an organic base is added, and the reaction is stirred to obtain the prepolymer. The prepolymer was uniformly dispersed in water, and then rotary evaporated to obtain a dispersion. The dispersion is impregnated onto a cotton fabric and then cured to obtain the castor oil-based waterborne polyurethane super-smooth cotton fabric.

[0021] In a preferred embodiment of the present invention, after mixing aliphatic polyisocyanate and monohydroxy-terminated polysiloxane, the mixture further includes a step of adding an organic solvent to reduce viscosity according to the viscosity of the system. The organic solvent is butanone (MEK). The present invention does not impose a special limit on the amount of butanone added, as long as the amount is sufficient to reduce the viscosity of the system and ensure that the reaction proceeds fully. For example, 4-10g of aliphatic polyisocyanate is added to 5mL of butanone.

[0022] In a preferred embodiment of the present invention, the aliphatic polyisocyanate is one of hexamethylene diisocyanate trimer, hexamethylene diisocyanate biuret, isophorone diisocyanate, and polytetrahydrofuran diisocyanate, the monohydroxy-terminated polysiloxane is monohydroxy-terminated polydimethylsiloxane, and the molar ratio of isocyanate groups in the aliphatic polyisocyanate to hydroxyl groups in the monohydroxy-terminated polysiloxane is 3:1 to 1:3.

[0023] In a preferred embodiment of the present invention, the temperature of reaction 1 is 60-80°C, the time is 1-3 hours, and the stirring speed is 800-1000 rpm. In a preferred embodiment of the present invention, after reaction 1 is completed, a hydrophilic chain extender and castor oil are added sequentially to the reaction system, and the process further includes a step of adding an organic solvent to reduce viscosity according to the viscosity of the system. The organic solvent is butanone (MEK). The present invention does not impose a special limit on the amount of butanone added, as long as the amount is sufficient to reduce the viscosity of the system and ensure that the reaction proceeds fully. As an example, 0.60-2.60g of 2,2-dimethylolpropionic acid is added to 50mL of butanone, ensuring that the butanone is added dropwise within 10min.

[0024] In a preferred embodiment of the present invention, the hydrophilic chain extender is 2,2-dihydroxymethylpropionic acid, and the molar ratio of the hydrophilic chain extender to the isocyanate group in the aliphatic polyisocyanate is 1:1-3.

[0025] In a preferred embodiment of the present invention, the mass ratio of the aliphatic polyisocyanate to castor oil is (1-10):(2-12).

[0026] More preferably, the mass ratio of the aliphatic polyisocyanate to castor oil is 1:2, 1:5, 1:7, 1:9, 1:1:12, 2:2, 2:5, 2:7, 2:9, 2:11, 3:2, 3:5, 3:7, 3:10, 4:2, 4:6, 4:8, 4:12, 5:2, 5:4, 5:6, 5:8, 5:12, 6:2, 6:5, 1:1, 6:8, 7:2, 7:6, 7:10, 7:12, 4:1, 8:5, 8:9, 9:2, 9:5, 9:7, 9:10, 5:1, 10:7, or 5:6.

[0027] In a preferred embodiment of the present invention, the temperature of reaction 2 is 60-80°C, the stirring speed is 800-1000 rpm, and the reaction endpoint is reached when the content of isocyanate group -NCO decreases to 1.3%-1.5%.

[0028] In a preferred embodiment of the present invention, the cooling is to reduce the temperature to 25-30°C.

[0029] In a preferred embodiment of the present invention, the organic base is triethylamine; the molar ratio of the hydrophilic chain extender to the organic base is 1:1.

[0030] In a preferred embodiment of the present invention, the temperature of the stirring reaction is 25-30°C and the time is 20-30 min.

[0031] In a preferred embodiment of the present invention, the prepolymer is uniformly dispersed in water by stirring dispersion, and the stirring parameters are set as follows: 25°C, 2000 rpm, 1 h. The dispersion obtained by rotary evaporation has a solid content of 30%-35%. The curing process involves preheating at 60-70℃ (optionally 60℃, 62℃, 65℃, 67℃ or 70℃) for 20-30 minutes (optionally 20 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes or 30 minutes), followed by heating at 130-150℃ (optionally 130℃, 135℃, 140℃, 145℃ or 150℃) for 1-3 minutes (optionally 1 minute, 1.5 minutes, 2 minutes, 2.5 minutes or 3 minutes).

[0032] A second aspect of the present invention provides a castor oil-based waterborne polyurethane super-smooth cotton fabric prepared by the above-described preparation method.

[0033] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0034] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0035] The slip angle test method follows the design standard of DIN 53119-2-1997. This equipment is used to test the anti-slip properties of fabrics. During the test, the fabric is rotated on a platform at a certain speed by electric drive, and the angle at which the droplet begins to slide is recorded by LCD digital display; this is the slip angle. The main technical parameters of the slip angle tester include a test angle range of 0-40° and a test speed of 1° / second.

[0036] Example 1 (1) Weigh 2.52 g of hexamethylene diisocyanate trimer (HDIT, molecular weight 252) and 30 g of hydroxyl-terminated polydimethylsiloxane (PDMS-OH, molecular weight 3000). Mix HDIT and PDMS-OH thoroughly and reduce viscosity with 5 mL of butanone (MEK) solvent. Then add the mixture to a 100 mL three-necked flask. Place the three-necked flask in a constant temperature oil bath at 70 °C and react continuously with mechanical stirring at 800 rpm for 1 h. (2) 1.34 g of 2,2-dimethylolpropionic acid (DMPA) and 5.61 g of castor oil (CO) were added sequentially to the three-necked flask in step (1), and the mixture was stirred at 1000 rpm for 10 min. After 10 min, the viscosity of the system increased. 50.0 mL of MEK was measured and slowly added dropwise to the three-necked flask through a constant pressure funnel to ensure that the MEK was added within 10 min to reduce the viscosity of the system. The reaction continued, and the content of isocyanate groups (-NCO) was detected during the reaction. The content of isocyanate groups (-NCO) in the reaction system was determined by titration using di-n-butylamine. When the content of -NCO decreased to about 1.4%, the reaction endpoint was determined. The system was cooled down. When the temperature dropped to 30 °C, triethylamine (TEA) with an equimolar amount of DMPA was added, and the mixture was stirred for 30 min to obtain the prepolymer. (3) The prepolymer from step (2) was transferred to a 250 mL three-necked flask and placed in a water bath at 25 °C. The mechanical stirring speed was set to 3000 rpm, and 60 mL of deionized water was added dropwise to the three-necked flask through a constant pressure funnel. The mixture was continuously dispersed for 1 h under high-speed stirring. The resulting dispersion was placed in a water bath at 70 °C and subjected to vacuum distillation using a rotary evaporator to remove the MEK solvent and some water from the system, finally obtaining a dispersion with a solid content of 30%. The above dispersion was used to perform a dip-and-pinch treatment on cotton fabric, which was then washed with anhydrous ethanol to remove residual reactants. The treated cotton fabric was pre-dried in a 60 °C oven for 30 min and finally baked in a baking oven at 150 °C for 3 min to obtain a super-smooth cotton fabric based on castor oil-based waterborne polyurethane.

[0037] Depend on Figure 1 As can be seen, after treatment, the fibers of the super-smooth cotton fabric are covered by a coating, indicating that castor oil-based waterborne polyurethane has been successfully applied to the surface of the cotton fabric.

[0038] Depend on Figure 2 It can be seen that carbonyl groups appear on the surface of the super-smooth cotton fabric, proving that castor oil-based waterborne polyurethane was successfully synthesized.

[0039] Depend on Figure 3 It can be seen that C, N, O, and Si elements appear on the surface of the super-smooth cotton fabric, indicating that castor oil-based waterborne polyurethane has been successfully applied to the cotton fabric.

[0040] Its sliding angle was tested to be 8.6°.

[0041] Example 2 The only difference from Example 1 is that the molar ratio of isocyanate group (-NCO) to hydroxyl group (-OH) is 1.5:1. All other steps and parameters are the same as in Example 1. The measured sliding angle is 8.2°.

[0042] Example 3 The only difference from Example 1 is that the molar ratio of isocyanate group (-NCO) to hydroxyl group (-OH) is 1:1.5. All other steps and parameters are the same as in Example 1. The measured sliding angle is 7.9°.

[0043] Example 4 The only difference from Example 1 is that the baking temperature was changed from 150°C to 140°C; all other steps and parameters are the same as in Example 1. The measured sliding angle was 11.3°.

[0044] Example 5 The only difference from Example 1 is that the baking time is changed from 3 minutes to 2 minutes; all other steps and parameters are the same as in Example 1. The sliding angle was tested to be 10.5°.

[0045] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a castor oil-based waterborne polyurethane super-smooth cotton fabric, characterized in that, Includes the following steps: Aliphatic polyisocyanate and monohydroxy-terminated polysiloxane were mixed and reacted under heating and stirring conditions; After reaction 1 is completed, a hydrophilic chain extender and castor oil are added to the reaction system in sequence, and reaction 2 is carried out under heating and stirring conditions. During the reaction, the reaction endpoint is determined by detecting the content of isocyanate groups -NCO. After the reaction endpoint is reached, the reaction system is cooled down, then an organic base is added, and the reaction is stirred to obtain the prepolymer. The prepolymer was uniformly dispersed in water, and then rotary evaporated to obtain a dispersion. The dispersion is impregnated onto a cotton fabric and then cured to obtain the castor oil-based waterborne polyurethane super-smooth cotton fabric.

2. The preparation method according to claim 1, characterized in that, The aliphatic polyisocyanate is one of hexamethylene diisocyanate trimer, hexamethylene diisocyanate biuret, isophorone diisocyanate, and polytetrahydrofuran diisocyanate. The monohydroxy-terminated polysiloxane is a monohydroxy-terminated polydimethylsiloxane. The molar ratio of isocyanate groups in the aliphatic polyisocyanate to hydroxyl groups in the monohydroxy-terminated polysiloxane is 3:1 to 1:

3.

3. The preparation method according to claim 1, characterized in that, The reaction 1 is carried out at a temperature of 60-80℃ for 1-3 hours and at a stirring speed of 800-1000 rpm.

4. The preparation method according to claim 1, characterized in that, The hydrophilic chain extender is 2,2-dihydroxymethylpropionic acid, and the molar ratio of the hydrophilic chain extender to the isocyanate group in the aliphatic polyisocyanate is 1:1-3.

5. The preparation method according to claim 1, characterized in that, The mass ratio of the aliphatic polyisocyanate to castor oil is (1-10):(2-12).

6. The preparation method according to claim 1, characterized in that, The reaction 2 is carried out at a temperature of 60-80℃ and a stirring speed of 800-1000 rpm. The reaction endpoint is reached when the content of isocyanate group -NCO decreases to 1.3%-1.5%.

7. The preparation method according to claim 1, characterized in that, The cooling refers to reducing the temperature to 25-30℃.

8. The preparation method according to claim 1, characterized in that, The organic base is triethylamine; the molar ratio of the hydrophilic chain extender to the organic base is 1:

1.

9. The preparation method according to claim 1, characterized in that, The curing process involves preheating at 60-70℃ for 20-30 minutes, followed by heating at 130-150℃ for 1-3 minutes.

10. A castor oil-based waterborne polyurethane super-smooth cotton fabric prepared by the preparation method according to any one of claims 1-9.

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