Preparation method of wettability Janus fabric and wettability Janus fabric

Abstract

The present application discloses a preparation method of a wettable Janus fabric and the wettable Janus fabric. The preparation method of the wettable Janus fabric includes: preparing a water-soluble terminal heptamethyltrisiloxanyl polyurethane; adding the water-soluble terminal heptamethyltrisiloxanyl polyurethane and a thickening agent into water to prepare a water-soluble protective coating with high viscosity; performing single-sided coating on a base fabric with the water-soluble protective coating, and then drying to obtain a single-sided protective coating fabric; preparing a low-viscosity superhydrophobic spraying liquid, performing superhydrophobic spraying treatment on the uncoated side of the single-sided protective coating fabric, and then drying to obtain a superhydrophobic-single-sided protective coating fabric; performing water washing and drying treatments on the obtained superhydrophobic-single-sided protective coating fabric to remove the water-soluble single-sided protective coating and obtain the wettable Janus fabric. The preparation method of the wettable Janus fabric provided by the present application can simultaneously solve the problems of a large difference in static contact angles between the hydrophobic surface and the hydrophilic surface of the wettable Janus fabric and high air permeability of the fabric.

Description

Technical Field

[0001] This application relates to the technical field of dyeing and finishing of textile fabrics, and particularly relates to a preparation method of a wettable Janus fabric and a wettable Janus fabric. Background Art

[0002] A wettable Janus fabric refers to a fabric with opposite wettabilities on its front and back sides, that is, one side is hydrophilic and the other side is hydrophobic. Due to its unique wettability, it has now received attention in application fields such as fog collection, oil-water separation, seawater desalination, sensors, unidirectional movement of bubbles, and unidirectional water conduction. Common preparation methods of wettable Janus fabrics include gradient electrospinning, unilateral electrostatic spraying, single-sided light treatment, single-sided coating, two-layer lamination, etc. However, methods such as electrospinning, unilateral electrostatic spraying, and single-sided light treatment have the advantage of a large difference in static contact angles between the hydrophobic surface and the hydrophilic surface, but according to the existing technology, their preparation efficiency is low; the single-sided coating technology has the advantage of large-scale mass production, and the thickeners contained in high-viscosity water-based hydrophobic coatings have a great impact on the hydrophobicity of the hydrophobic surface. Usually, its static contact angle is difficult to exceed 150°, and the coating formed by the high-viscosity coating has a great impact on the air permeability of the fabric; two-layer lamination is to laminate a hydrophilic fabric and a hydrophobic fabric using an adhesive, and the adhesion strength is negatively correlated with the hydrophobicity of the hydrophobic fabric, and the high-viscosity adhesive will also have a great impact on the air permeability of the fabric, while the low-viscosity adhesive will reduce the hydrophilicity and hydrophobicity of the hydrophilic surface and the hydrophobic surface due to penetration.

[0003] Thus, it is difficult for the existing technology to achieve a balance among a large difference in static contact angles between the hydrophobic surface and the hydrophilic surface of the wettable Janus fabric, high air permeability of the fabric, and mass production. In order to overcome the problems existing in these existing technologies, industry players are also actively conducting research and development, developing a new heptamethyltrisiloxanyl polyurethane end-capping agent and preparing water-soluble heptamethyltrisiloxanyl polyurethane, and using this as the main body of the protective coating to provide a new processing technology for wettable Janus fabrics. Currently, no process for preparing a wettable Janus fabric by introducing a protective coating has been seen.

[0004] Therefore, it is desired to have a technical solution to solve or at least alleviate the above deficiencies of the existing technology. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method of a wettable Janus fabric to at least solve one of the above technical problems.

[0006] In one aspect of the present invention, there is provided a preparation method of a wettable Janus fabric, and the preparation method of the wettable Janus fabric includes:

[0007] Preparing water-soluble heptamethyltrisiloxanyl polyurethane;

[0008] Add water-soluble heptamethyltrisiloxanyl polyurethane and a thickening agent to water to prepare a water-soluble protective coating with high viscosity;

[0009] Perform single-sided coating on the base fabric with the water-soluble protective coating, and then dry it to obtain a single-sided protective coating fabric;

[0010] Prepare a low-viscosity superhydrophobic spraying liquid, perform hydrophobic spraying treatment on the uncoated side of the single-sided protective coating fabric, and then dry it to obtain a superhydrophobic-single-sided protective coating fabric;

[0011] Wash and dry the obtained superhydrophobic-single-sided protective coating fabric to remove the water-soluble single-sided protective coating and obtain a wettable Janus fabric.

[0012] Optionally, the preparation of the water-soluble heptamethyltrisiloxanyl polyurethane includes:

[0013] Using 1,1,1,3,5,5,5-heptamethyltrisiloxane and allyl glycidyl ether as raw materials, and chloroplatinic acid as a catalyst to synthesize 1,1,1,3,5,5,5-heptamethyl-3(1-ethyl-2,3-epoxypropoxy)trisiloxane, and using the chloroplatinic acid-catalyzed synthesis of 1,1,1,3,5,5,5-heptamethyl-3(1-ethyl-2,3-epoxypropoxy)trisiloxane as the heptamethyltrisiloxanyl capping agent of the polyurethane;

[0014] Prepare a prepolymer with an isocyanate group at the end using a diisocyanate and a polyol;

[0015] Add a solvent, a small molecule diol hydrophilic chain extender, and a catalyst dibutyltin dilaurate to the prepolymer for chain extension to obtain an isocyanate group-terminated polyurethane;

[0016] Add diamine to the isocyanate group-terminated polyurethane under low temperature conditions to obtain an amino group-terminated polyurethane;

[0017] Add the heptamethyltrisiloxanyl capping agent to the amino group-terminated polyurethane and carry out a temperature-raising reaction to obtain heptamethyltrisiloxanyl polyurethane;

[0018] Add a salifying agent to the heptamethyltrisiloxanyl polyurethane to obtain the water-soluble heptamethyltrisiloxanyl polyurethane.

[0019] Optionally, the diisocyanate is one or a combination of more of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI);

[0020] The polyol is one or a combination of polycaprolactone, polyethylene adipate glycol, polytetrahydrofuran glycol, polypropylene glycol, polybutylene adipate diol, polyethylene glycol;

[0021] The small molecule diol hydrophilic chain extender is one or a combination of dimethylolpropionic acid, dimethylolbutyric acid, dimethylolhydantoin, N-methyldiethanolamine;

[0022] The salt-forming agent is triethylamine, ammonia water or glacial acetic acid. The finally synthesized polyurethane is heptamethyltrisiloxanyl-terminated polyurethane.

[0023] Optionally, the thickener in the water-soluble protective coating is one or a combination of polyurethane associative thickeners, cellulose thickeners, polyacrylate thickeners, natural rubber thickeners;

[0024] The mass fraction of the water-soluble polymer is 2-30%, and the viscosity of the water-soluble protective coating is 200-30000 mPa·s.

[0025] Optionally, the superhydrophobic spraying liquid is composed of three parts: an adhesive, an organic solvent, and a hydrophobic agent; among them,

[0026] The total solute mass fraction of the superhydrophobic spraying liquid is 5-70%, and the viscosity of the superhydrophobic spraying liquid is 1-50 mPa·s.

[0027] Optionally, the adhesive of the superhydrophobic spraying liquid is one or a combination of epoxy resins, polyurethanes, polyacrylates, and cyanoacrylates that can be dissolved in organic solvents;

[0028] The hydrophobic agent of the superhydrophobic spraying liquid is one or a combination of long-chain alkylchlorosilanes, perfluoroalkylchlorosilanes, alkylalkoxysilanes, perfluoroalkylalkoxysilanes, polyhedral oligomeric silsesquioxanes, and fluorinated polyhedral oligomeric silsesquioxanes.

[0029] Optionally, the drying temperature of the superhydrophobic-one-sided protective coating fabric is 40-60 °C, and the drying time is 5-120 min.

[0030] Optionally, in the water washing treatment of the obtained superhydrophobic-one-sided protective coating fabric, the washing temperature of the water washing treatment is 40-90 °C, the washing time is 5-100 min; the drying temperature is 40-100 °C, and the drying time is 5-120 min.

[0031] This application also provides a wettable Janus fabric, and the wettable Janus fabric is prepared by the preparation method of the wettable Janus fabric as described above.

[0032] Optionally, the contact angle of the hydrophilic surface of the wettability Janus fabric is <90°, the contact angle of the hydrophobic surface is >90°, and the air permeability is >20 mm / s when the test pressure difference is 100 Pa.

[0033] Beneficial effects

[0034] The preparation method of the wettability Janus fabric of the present application has the following advantages:

[0035] (1) The present invention combines a coating process to synthesize a new type of water-soluble terminal heptamethyltrisiloxanyl polyurethane. The heptamethyltrisiloxanyl group in it has excellent permeability and spreading ability due to its special molecular structure, and can firmly adhere to the surface of high-surface-energy fibers, ensuring the uniformity and stability of the coating during the coating process. A large number of hydrophilic groups in the polyurethane can ensure that the protective coating dissolves rapidly in water. The above characteristics of the newly synthesized polyurethane enable it to protect the hydrophilic surface of the fabric from being infiltrated by low-viscosity hydrophobic coatings, and after washing, the excellent hydrophilicity of the hydrophilic surface of the wettability Janus fabric can be maintained, and the difference in static contact angles between the hydrophobic surface and the hydrophilic surface can exceed 160° at most.

[0036] (2) The binder in the low-viscosity hydrophobic spraying liquid used in the present invention can form a strong force between the fiber and the water repellent, firmly fixing the water repellent on the fabric surface, thereby ensuring the durability (abrasion resistance and washability) of the function in the application of the hydrophobic surface of the wettability Janus fabric.

[0037] (3) The use of the low-viscosity hydrophobic spraying liquid in the present invention is conducive to diffusion on the fabric fiber surface and in the fiber gaps, and will not block the pores in the fabric, enabling the wettability Janus fabric to have excellent air permeability.

[0038] (4) The process of the present invention has strong applicability and can be mass-produced on a large scale through the existing equipment in ordinary dyeing and finishing workshops to improve the production efficiency of the wettability Janus fabric. Description of the drawings

[0039] Figure 1 is a schematic flow chart of the preparation method of the wettability Janus fabric provided by an embodiment of the present application.

[0040] Figure 2 is a schematic diagram of the synthesis of 1,1,1,3,5,5,5-heptamethyl-3-(1-ethyl-2,3-epoxypropoxy)trisiloxane in an embodiment of the present application.

[0041] Figure 3 is a schematic diagram of the synthesis of terminal heptamethyltrisiloxanyl polyurethane in an embodiment of the present application.

[0042] Figure 4 is a schematic diagram of the preparation process of the wettability Janus fabric in an embodiment of the present application;

[0043] Figure 5 Schematic structural diagram of the wettable Janus fabric prepared in an embodiment of the present application;

[0044] Figure 6 Static contact angles of the hydrophobic and hydrophilic surfaces of the wettable Janus fabric prepared in an embodiment of the present application.

[0045] Figure 7 Visualization photos of the hydrophobic and hydrophilic surfaces of the wettable Janus fabric prepared in an embodiment of the present application. Detailed implementation manners

[0046] To make the purpose, technical solutions and advantages of the implementation of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings in the embodiments of the present application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, of the embodiments of the present application. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application and should not be construed as limiting the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application. The embodiments of the present application will be described in detail below with reference to the drawings.

[0047] Figure 1 Schematic flow diagram of the preparation method of the wettable Janus fabric provided in an embodiment of the present application.

[0048] As Figure 1 shown, the preparation method of the wettable Janus fabric includes:

[0049] Step 1: Prepare water-soluble terminal heptamethyltrisiloxanyl polyurethane;

[0050] Step 2: Add the water-soluble terminal heptamethyltrisiloxanyl polyurethane and a thickener into water to prepare a water-soluble protective coating with high viscosity;

[0051] Step 3: Apply the water-soluble protective coating to one side of the base fabric by single-sided coating, and then dry it to obtain a single-sided protective coating fabric;

[0052] Step 4: Prepare a low-viscosity superhydrophobic spraying liquid, perform hydrophobic spraying treatment on the uncoated side of the single-sided protective coating fabric, and then dry it to obtain a superhydrophobic - single-sided protective coating fabric;

[0053] Step 5: Wash and dry the obtained superhydrophobic - single - sided protected coating fabric to remove the water - soluble single - sided protective coating, and obtain a wettable Janus fabric.

[0054] The preparation method of the wettable Janus fabric of the present application has the following advantages:

[0055] (1) The present invention combines a coating process to synthesize a novel water - soluble terminal heptamethyltrisiloxanyl polyurethane. The heptamethyltrisiloxane group has excellent permeability and spreading ability due to its special molecular structure, and can firmly adhere to the surface of high - surface - energy fibers, ensuring the uniformity and stability of the coating during the coating process. A large number of hydrophilic groups in the polyurethane can ensure that the protective coating dissolves rapidly in water. The above characteristics of the newly synthesized polyurethane enable it to protect the hydrophilic surface of the fabric from being infiltrated by low - viscosity hydrophobic coatings. After washing, the wettable Janus fabric can maintain excellent hydrophilicity on the hydrophilic surface, and the difference in static contact angles between the hydrophobic surface and the hydrophilic surface can exceed 160° at most. Specifically, heptamethyltrisiloxane has a unique "umbrella - like" structure, which contains seven Si - CH3 groups with a lower surface energy than C - CH3. In addition, due to the relatively long bond length of the Si - O - Si bond, it has excellent flexibility, which is more conducive to its spreading and penetration. The end - capping agent synthesized from heptamethyltrisiloxane and allyl glycidyl ether used in this application provides this group for the polyurethane, making the polyurethane have high permeability and spreading ability.

[0056] (2) The binder in the low - viscosity superhydrophobic spraying liquid used in the present invention can form a strong force between the fibers and the hydrophobic agent, firmly fixing the hydrophobic agent on the fabric surface, thereby ensuring the durability (wear resistance and wash resistance) of the function in the application of the hydrophobic surface of the wettable Janus fabric.

[0057] (3) The use of low - viscosity hydrophobic spraying liquid is conducive to diffusion on the surface and in the gaps of fabric fibers, and will not block the pores in the fabric, enabling the wettable Janus fabric to have excellent air permeability.

[0058] (4) The process of the present invention has strong applicability and can be mass - produced on a large scale through the existing equipment in ordinary dyeing and finishing workshops to improve the production efficiency of the wettable Janus fabric.

[0059] In this embodiment, the preparation of the water - soluble terminal heptamethyltrisiloxanyl polyurethane includes:

[0060] See Figure 2 and Figure 3, using 1,1,1,3,5,5,5 - heptamethyltrisiloxane and allyl glycidyl ether as raw materials and chloroplatinic acid as a catalyst to synthesize 1,1,1,3,5,5,5 - heptamethyl - 3(1 - ethyl - 2,3 - epoxypropoxy)trisiloxane, and the chloroplatinic acid - catalyzed synthesis of 1,1,1,3,5,5,5 - heptamethyl - 3(1 - ethyl - 2,3 - epoxypropoxy)trisiloxane is used as a heptamethyltrisiloxanyl capping agent for polyurethane;

[0061] Preparing a prepolymer with terminal isocyanate groups from a diisocyanate and a polyol;

[0062] Adding a solvent, a small - molecule diol hydrophilic chain extender, and a catalyst dibutyltin dilaurate into the prepolymer for chain extension to obtain a terminal - isocyanate - group polyurethane; in this embodiment, the solvent added into the prepolymer can be acetone, methyl ethyl ketone, N,N - dimethylformamide, etc.

[0063] Under low - temperature (0 °C - 10 °C) conditions, adding a diamine into the terminal - isocyanate - group polyurethane to obtain a terminal - amino polyurethane;

[0064] Adding the heptamethyltrisiloxanyl capping agent into the terminal - amino polyurethane and carrying out a temperature - rising reaction (rising to between 40 °C and 70 °C) to obtain a terminal - heptamethyltrisiloxanyl polyurethane;

[0065] Adding a salt - forming agent into the terminal - heptamethyltrisiloxanyl polyurethane to obtain the water - soluble terminal - heptamethyltrisiloxanyl polyurethane.

[0066] In this embodiment, the diisocyanate is one or a combination of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI);

[0067] The polyol is one or a combination of polycaprolactone, polyethylene adipate glycol, polytetrahydrofuran glycol, polypropylene glycol, polybutylene adipate diol, polyethylene glycol;

[0068] The small - molecule diol hydrophilic chain extender is one or a combination of dimethylolpropionic acid, dimethylolbutyric acid, dimethylolhydantoin, N - methyldiethanolamine;

[0069] The salt - forming agent is triethylamine, ammonia water or glacial acetic acid. The finally synthesized polyurethane is a terminal - heptamethyltrisiloxanyl polyurethane.

[0070] In this embodiment, the thickener in the water-soluble protective coating is one or a combination of polyurethane associative thickeners, cellulose thickeners, polyacrylate thickeners, and natural rubber thickeners;

[0071] The mass fraction of the water-soluble polymer is 2 to 30%, and the viscosity of the water-soluble protective coating is 200 to 30,000 mPa·s.

[0072] In this embodiment, the composition of the superhydrophobic spraying liquid consists of three parts: an adhesive, an organic solvent, and a water repellent; among them,

[0073] The total solute mass fraction of the superhydrophobic spraying liquid is 5 to 70%, and the viscosity of the superhydrophobic spraying liquid is 1 to 50 mPa·s.

[0074] In this embodiment, the adhesive of the superhydrophobic spraying liquid is one or a combination of epoxy resins, polyurethanes, polyacrylates, and cyanoacrylates that are soluble in organic solvents;

[0075] The water repellent of the superhydrophobic spraying liquid is one or a combination of long-chain alkyl chlorosilanes, perfluoroalkyl chlorosilanes, alkylalkoxysilanes, perfluoroalkylalkoxysilanes, polyhedral oligomeric silsesquioxanes, and fluorinated polyhedral oligomeric silsesquioxanes.

[0076] In this embodiment, the drying temperature of the superhydrophobic - single-sided protective coating fabric is 40 to 60 °C, and the drying time is 5 to 120 min.

[0077] In this embodiment, in the water washing treatment of the obtained superhydrophobic - single-sided protective coating fabric, the washing temperature of the water washing treatment is 40 to 90 °C, the washing time is 5 to 100 min; the drying temperature is 40 to 100 °C, and the drying time is 5 to 120 min.

[0078] This application also provides a wettable Janus fabric, which is characterized in that the wettable Janus fabric is prepared by the preparation method of the wettable Janus fabric as described above.

[0079] In this embodiment, for the wettable Janus fabric prepared by the above method, the contact angle of the hydrophilic surface < 90°, the contact angle of the hydrophobic surface > 90°, and the air permeability > 20 mm / s when the test pressure difference is 100 Pa.

[0080] The following further elaborates on this application by way of examples. It can be understood that these examples do not constitute any limitation to this application.

[0081] Referring to Figure 4, the principle of the present invention to solve the above problems is as follows: First, 1,1,1,3,5,5,5-heptamethyl-3(1-ethyl-2,3-epoxypropoxy)trisiloxane was synthesized as the heptamethyltrisiloxanyl capping agent for polyurethane. Using this as the capping agent, water-soluble terminal heptamethyltrisiloxanyl polyurethane was synthesized as a water-based protective coating. The heptamethyltrisiloxanyl group has excellent permeability and spreading ability due to its special molecular structure, and can firmly adhere to the surface of high surface energy fibers, ensuring the uniformity and stability of the coating during the coating process. A large number of hydrophilic groups in the polyurethane can ensure that the protective coating dissolves rapidly in water. Secondly, based on these two characteristics, using a single-sided coating process, by adding a thickening agent to adjust the viscosity of the water-based protective coating, the thickness of the coated layer can be controlled, so that the hydrophilic fibers on one side of the fabric are covered by the protective coating formed by the protective coating, and the hydrophilic fibers on the other side are exposed. Then, through a spraying process, a low-viscosity superhydrophobic spraying liquid is arranged on the exposed hydrophilic fibers. Due to the presence of organic solvents in the low-viscosity spraying liquid, its surface tension is extremely low, and it can quickly penetrate to the surface of the hydrophilic fibers in the fabric and combine with the fiber surface with strong forces (covalent bonds, ionic bonds or hydrogen bonds, etc.), and can ensure large pores on the hydrophobic surface. At this time, the protective coating can prevent the hydrophobic spraying liquid from penetrating to the fibers covered by the protective coating. Finally, through a water washing process, the water-soluble protective coating is washed away, and the protected hydrophilic fibers are exposed again. To achieve the effect of hydrophobic on one side, hydrophilic on the other side and high breathability. Based on the above principle, the embodiments in this specification provide a preparation method of a wettability Janus fabric, including:

[0082] Step 1: Prepare water-soluble terminal heptamethyltrisiloxanyl polyurethane; specifically,

[0083] Step 11: Using 1,1,1,3,5,5,5-heptamethyltrisiloxane and allyl glycidyl ether as raw materials, chloroplatinic acid as a catalyst, synthesize 1,1,1,3,5,5,5-heptamethyl-3(1-ethyl-2,3-epoxypropoxy)trisiloxane under certain temperature conditions (100°C - 130°C), and then refine it as the heptamethyltrisiloxanyl capping agent for polyurethane.

[0084] Step 12: React diisocyanate and polyol at a certain temperature to prepare a prepolymer with an isocyanate group at the end, then add a solvent, a small molecule diol hydrophilic chain extender and a catalyst dibutyltin dilaurate for chain extension to obtain terminal isocyanate group polyurethane. Add diamine at low temperature (0°C - 10°C) to obtain terminal amino polyurethane. Add the prepared heptamethyltrisiloxanyl capping agent, raise the temperature and react (40°C - 70°C) for a certain time to obtain terminal heptamethyltrisiloxanyl polyurethane, and then add a salt-forming agent to obtain water-soluble terminal heptamethyltrisiloxanyl polyurethane.

[0085] Step 2: Add the terminal heptamethyltrisiloxanyl polyurethane prepared in Step 1 and a thickener into water in a certain ratio (1:1 to 1:10) to prepare a water-soluble protective coating with high viscosity.

[0086] Step 3: Perform single-sided coating on the base fabric, and then dry it to obtain a single-sided protective coating fabric.

[0087] Step 4: Prepare a low-viscosity superhydrophobic spraying solution, perform hydrophobic spraying treatment on the uncoated side of the single-sided protective coating fabric, and then dry it to obtain a superhydrophobic - single-sided protective coating fabric.

[0088] Step 5: Wash the obtained superhydrophobic - single-sided protective coating fabric to remove the water-soluble single-sided protective coating, and obtain a wettable Janus fabric (see Figure 5 ).

[0089] See Figure 6 , in this embodiment, the base fabric in Step 1 is a fabric with a static contact angle with water less than 90°.

[0090] In this embodiment, in Step 1, using 1,1,1,3,5,5,5 - heptamethyltrisiloxane and allyl glycidyl ether as raw materials, chloroplatinic acid as a catalyst, the end-capping agent synthesized at 120°C is 1,1,1,3,5,5,5 - heptamethyl - 3(1 - ethyl - 2,3 - epoxypropoxy) trisiloxane.

[0091] In this embodiment, the diisocyanate in Step 12 is one or a combination of more than one of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI); the polyol is one or a combination of more than one of polycaprolactone, polyethylene adipate glycol / polytetrahydrofuran glycol, polypropylene glycol, polybutylene adipate diol, polyethylene glycol; the small molecule diol hydrophilic chain extender is one or a combination of more than one of dimethylolpropionic acid, dimethylolbutyric acid, dimethylolhydantoin, N - methyldiethanolamine; the salt-forming agent is triethylamine, ammonia water or glacial acetic acid. The finally synthesized polyurethane is terminal heptamethyltrisiloxanyl polyurethane.

[0092] In this embodiment, the thickener in the water-soluble protective coating in Step 3 is one or a combination of more than one of polyurethane associative thickeners, cellulose thickeners, polyacrylate thickeners, and natural rubber thickeners. The mass fraction of the water-soluble polymer is 2 - 30%, and the viscosity of the water-soluble protective coating is 200 - 30000 mPa·s.

[0093] In this embodiment, the drying temperature of the single-sided protective coating fabric in step 3 is 80-120 °C, and the drying time is 1-20 min.

[0094] In this embodiment, the composition of the superhydrophobic spraying liquid in step 4 consists of an adhesive, a solvent, and a water repellent; the mass fraction of the superhydrophobic spraying liquid is 5-70%, and the viscosity is 1-50 mPa·s.

[0095] In this embodiment, the adhesive of the superhydrophobic spraying liquid in step 4 is one or a combination of epoxy resins, polyurethanes, polyacrylates, and cyanoacrylates that are soluble in organic solvents; the water repellent of the superhydrophobic spraying liquid is one or a combination of long-chain alkyl chlorosilanes, perfluoroalkyl chlorosilanes, alkylalkoxysilanes, perfluoroalkylalkoxysilanes, alkyl polyhedral oligomeric silsesquioxanes, and fluorinated polyhedral oligomeric silsesquioxanes.

[0096] In this embodiment, the drying temperature of the hydrophobic-single-sided protective coating fabric in step 4 is 40-60 °C, and the drying time is 5-120 min.

[0097] In this embodiment, the washing temperature of the wettable Janus fabric in step 5 is 40-90 °C, and the washing time is 5-100 min; the drying temperature is 40-100 °C, and the drying time is 5-120 min.

[0098] See Figure 7 , in this embodiment, the static contact angle of the hydrophilic surface of the wettable Janus fabric in step 5 is <10°, the static contact angle of the hydrophobic surface is >150°, and the air permeability is >40 mm / s when the test pressure difference is 100 Pa.

[0099] In this embodiment, in the examples, the experimental methods used are all conventional methods unless otherwise specified. The equipment, materials, reagents, etc. used can all be obtained from commercial channels unless otherwise specified. According to the GB / T 5453-1997 standard, the air permeability of the fabric is measured using a YG461E fabric air permeability tester. The test sample size is (100×100) mm2, and the test air pressure difference is 100 Pa. Specific Example 1

[0101] A preparation method of a wettable Janus linen fabric, the steps are as follows:

[0102] Step 1: Using 222 g of 1,1,1,3,5,5,5-heptamethyltrisiloxane and 125 g of allyl glycidyl ether as raw materials, adding 0.2 g of an isopropanol solution of 0.1% chloroplatinic acid as a catalyst, reacting at 120 °C for 3 h to synthesize 1,1,1,3,5,5,5-heptamethyl-3(1-ethyl-2,3-epoxypropoxy)trisiloxane, and then refining it to be used as a heptamethyltrisiloxanyl capping agent for polyurethane.

[0103] Step 2: Reacting 48.8 g of isophorone diisocyanate and 300 g of poly(ethylene adipate)diol (M = 2000) at 80 °C for 30 min to prepare a prepolymer with isocyanate groups at the ends, then adding 50 g of acetone, 6.7 g of dimethylolpropionic acid and 0.02 g of dibutyltin dilaurate for chain extension to obtain a polyurethane with isocyanate groups at the ends. Adding 1.2 g of ethylenediamine in a 5 °C ice bath and reacting for 20 min to obtain an amino-terminated polyurethane. Adding 6.72 g of 1,1,1,3,5,5,5-heptamethyl-3(1-ethyl-2,3-epoxypropoxy)trisiloxane and reacting at 60 °C for 1 h to obtain a heptamethyltrisiloxanyl-terminated polyurethane, and then adding 8 g of triethylamine and stirring vigorously to obtain a water-soluble heptamethyltrisiloxanyl-terminated polyurethane.

[0104] Step 3: Formulating a water-soluble protective coating with water-soluble heptamethyltrisiloxanyl-terminated polyurethane (8%), a polyacrylamide thickener (4%) and the balance of water. The viscosity of the solution is 3100 mPa·s. Coating one side of a plain weave linen fabric, setting the temperature of the forced air oven at 100 °C and the drying time at 3 min to obtain a one-sided protective coated fabric.

[0105] Step 4: Dissolving butyl cyanoacrylate (18%), polymethyl methacrylate (2%) and fluorinated polyhedral oligomeric silsesquioxane (18%) in Asahiklin 225 (62%) according to the mass ratio to prepare a superhydrophobic spraying liquid with a viscosity of 12 mPa·s. Performing hydrophobic spraying treatment on the uncoated side of the one-sided protective coated fabric, setting the temperature of the forced air oven at 70 °C and the drying time at 10 min to obtain a superhydrophobic-one-sided protective coated fabric.

[0106] Step 5: Washing the obtained superhydrophobic-one-sided protective coated fabric at a washing temperature of 80 °C for 7 min to remove the water-soluble one-sided protective coating. The oven temperature is 70 °C and the drying time is 20 min to obtain a wettable Janus linen fabric.

[0107] After testing, it can be obtained that the static contact angle of the hydrophobic surface of the prepared wettability Janus hemp fabric is 160°, the static contact angle of the hydrophilic surface becomes 0° in 0.5 s, and the difference in static contact angle between the hydrophobic surface and the hydrophilic surface is 160°. The air permeability is 114 mm / s under the condition of a pressure difference of 100 Pa. After 5000 abrasion resistance tests, the static contact angle of the hydrophobic surface is 158°, the static contact angle of the hydrophilic surface is 0°, and the air permeability remains unchanged. After 20 standard water washes, the static contact angle of the hydrophobic surface is 155°, the static contact angle of the hydrophilic surface is 0°, and the air permeability remains unchanged. Specific Example 2

[0109] A preparation method of a wettability Janus aramid fabric comprises the following steps:

[0110] Step 1: Using 222 g of 1,1,1,3,5,5,5-heptamethyltrisiloxane and 125 g of allyl glycidyl ether as raw materials, adding 0.3 g of an isopropanol solution of 0.1% chloroplatinic acid as a catalyst, reacting at 120 °C for 2 h to synthesize 1,1,1,3,5,5,5-heptamethyl-3(1-ethyl-2,3-epoxypropoxy)trisiloxane, and then refining it to be used as a heptamethyltrisiloxanyl end-capping agent for polyurethane.

[0111] Step 2: Reacting 55 g of diphenylmethane-4,4'-diisocyanate and 300 g of polytetrahydrofuran diol (M = 2000) at 80 °C for 30 min to prepare a prepolymer with isocyanate groups at the ends, then adding 40 g of acetone, 10 g of N,N-dimethylformamide, 6 g of N-methyldiethanolamine and 0.02 g of dibutyltin dilaurate for chain extension to obtain an isocyanate-terminated polyurethane, adding 1.2 g of ethylenediamine in a 5 °C ice bath, reacting for 20 min to obtain an amino-terminated polyurethane, adding 6.72 g of 1,1,1,3,5,5,5-heptamethyl-3(1-ethyl-2,3-epoxypropoxy)trisiloxane, reacting at 60 °C for 1 h to obtain a heptamethyltrisiloxanyl-terminated polyurethane, and then adding 3 g of glacial acetic acid and stirring vigorously to obtain a water-soluble heptamethyltrisiloxanyl-terminated polyurethane.

[0112] Step 3: Formulating a water-soluble protective coating with water-soluble heptamethyltrisiloxanyl-terminated polyurethane (10%), a polyurethane associative thickener (4%) and the balance of water, the viscosity of the solution is 2800 mPa·s, and performing single-sided coating on a twill meta-aramid fabric, setting the temperature of the blast drying oven to 90 °C and the drying time to 6 min to obtain a single-sided protected coated fabric.

[0113] Step 4: Dissolve butyl cyanoacrylate (26.7%) and perfluorooctyltrichlorosilane (6.7%) into 1,1-dichloro-1-fluoroethane (66.6%) according to the mass ratio to prepare a superhydrophobic spraying solution with a viscosity of 3 mPa·s. Perform hydrophobic spraying treatment on the uncoated side of the single-sided protective coating fabric. Set the temperature of the blast drying oven to 60°C and the drying time to 60 min to obtain a superhydrophobic-single-sided protective coating fabric.

[0114] Step 5: Wash the obtained superhydrophobic-single-sided protective coating fabric at a washing temperature of 80°C for 7 min to remove the water-soluble single-sided protective coating. Set the oven temperature to 80°C and the drying time to 10 min to obtain a wettable Janus fabric.

[0115] Through testing, it can be obtained that the static contact angle of the hydrophobic surface of the prepared wettable Janus aramid fabric is 163.5°, the static contact angle of the hydrophilic surface becomes 0° in 3.2 s, and the difference in the static contact angle between the hydrophobic surface and the hydrophilic surface is 163.5°. The air permeability is 121 mm / s under the condition of a pressure difference of 100 Pa. After 5000 times of abrasion resistance testing, the static contact angle of the hydrophobic surface is 158.5° and the static contact angle of the hydrophilic surface is 0°, and the air permeability remains unchanged. After 20 times of standard washing, the static contact angle of the hydrophobic surface is 151.5° and the static contact angle of the hydrophilic surface is 0°, and the air permeability remains unchanged.

[0116] In addition, it is obvious that the word "comprising" does not exclude other units or steps. The multiple units, modules or devices stated in the apparatus claims can also be implemented by one unit or a general apparatus through software or hardware.

[0117] Although the present invention has been described in detail with general descriptions and specific embodiments above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A preparation method of a wettability Janus fabric, characterized in that, The preparation method of the wettability Janus fabric includes: Preparing water-soluble terminal heptamethyltrisiloxanyl polyurethane; Adding the water-soluble terminal heptamethyltrisiloxanyl polyurethane and a thickener into water to prepare a water-soluble protective coating with high viscosity; Single-sidedly coating a substrate fabric with the water-soluble protective coating, and then drying to obtain a single-sided protective coating fabric; Preparing a low-viscosity superhydrophobic spraying liquid, performing hydrophobic spraying treatment on the uncoated side of the single-sided protective coating fabric, and then drying to obtain a superhydrophobic-single-sided protective coating fabric; wherein, the composition of the superhydrophobic spraying liquid consists of an adhesive, an organic solvent, and a hydrophobic agent; the mass fraction of the superhydrophobic spraying liquid is 5-70%, and the viscosity is 1-50 mPa·s; Performing water washing and drying treatments on the obtained superhydrophobic-single-sided protective coating fabric to remove the water-soluble single-sided protective coating, thereby obtaining the wettability Janus fabric.

2. The preparation method of the wettability Janus fabric according to claim 1, characterized in that, The preparation of the water-soluble terminal heptamethyltrisiloxanyl polyurethane includes: Using 1,1,1,3,5,5,5-heptamethyltrisiloxane and allyl glycidyl ether as raw materials, and chloroplatinic acid as a catalyst to synthesize 1,1,1,3,5,5,5-heptamethyl-3-(1-ethyl-2,3-epoxypropoxy)trisiloxane, and using the chloroplatinic acid-catalyzed synthesis of 1,1,1,3,5,5,5-heptamethyl-3-(1-ethyl-2,3-epoxypropoxy)trisiloxane as the heptamethyltrisiloxanyl capping agent of the polyurethane; Preparing a prepolymer with terminal isocyanate groups using a diisocyanate and a polyol; Adding a solvent, a small molecule diol hydrophilic chain extender, and a catalyst dibutyltin dilaurate into the prepolymer for chain extension to obtain a terminal isocyanate group polyurethane; Adding a diamine to the terminal isocyanate group polyurethane under low-temperature conditions to obtain a terminal amino polyurethane; Adding the heptamethyltrisiloxanyl capping agent into the terminal amino polyurethane and performing a temperature-raising reaction to obtain a terminal heptamethyltrisiloxanyl polyurethane; Adding a salifying agent into the heptamethyltrisiloxanyl polyurethane to obtain the water-soluble terminal heptamethyltrisiloxanyl polyurethane.

3. The preparation method of the wettability Janus fabric according to claim 2, characterized in that, The diisocyanate is one or a combination of more of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI); The polyol is one or a combination of more of polycaprolactone, polyethylene adipate glycol, polytetrahydrofuran glycol, polypropylene glycol, polybutylene adipate diol, polyethylene glycol; The small molecule diol hydrophilic chain extender is one or a combination of more of dimethylolpropionic acid, dimethylolbutyric acid, dimethylolhydantoin, N-methyldiethanolamine; The salifying agent is triethylamine, ammonia water or glacial acetic acid, and the finally synthesized polyurethane is a terminal heptamethyltrisiloxanyl polyurethane.

4. The preparation method of the wettability Janus fabric according to claim 3, characterized in that, The thickener is one or a combination of more of a polyurethane associative thickener, a cellulose thickener, a polyacrylate thickener, a natural rubber thickener; The mass fraction of the water-soluble terminal heptamethyltrisiloxanyl polyurethane is 2 to 30%, and the viscosity of the water-soluble protective coating is 200 to 30,000 mPa·s.

5. The preparation method of the wettability Janus fabric according to claim 4, characterized in that, The binder of the superhydrophobic spraying liquid is one or a combination of epoxy resins, polyurethanes, polyacrylates, and cyanoacrylates that are soluble in organic solvents; The water repellent of the superhydrophobic spraying liquid is a combination of one or more of long-chain alkylchlorosilanes, perfluoroalkylchlorosilanes, alkylalkoxysilanes, perfluoroalkylalkoxysilanes, polyhedral oligomeric silsesquioxanes, and fluorinated polyhedral oligomeric silsesquioxanes.

6. The preparation method of the wettability Janus fabric according to claim 5, characterized in that, The drying temperature of the superhydrophobic - single-sided protective coating fabric is 40 to 60 °C, and the drying time is 5 to 120 min.

7. The preparation method of the wettability Janus fabric according to claim 6, characterized in that, In the water washing treatment of the obtained superhydrophobic - single-sided protective coating fabric, the washing temperature of the water washing treatment is 40 to 90 °C, the washing time is 5 to 100 min; the drying temperature is 40 to 100 °C, and the drying time is 5 to 120 min.

8. A wettability Janus fabric, characterized in that, The wettable Janus fabric is prepared by the preparation method of the wettable Janus fabric according to any one of claims 1 to 7.

9. The wettability Janus fabric according to claim 8, wherein, The contact angle of the hydrophilic surface of the wettable Janus fabric is < 90°, the contact angle of the hydrophobic surface is > 90°, and the air permeability is > 20 mm / s when the test pressure difference is 100 Pa.

Images