Preparation method of core-shell fluorine-free super-hydrophobic emulsion based on polyurethane pressure-sensitive adhesive property

Abstract

The invention relates to a preparation method of a core-shell fluorine-free super-hydrophobic emulsion based on polyurethane pressure-sensitive adhesive viscosity. According to the method, a seed emulsion polymerization one-pot method is adopted, a hydrophilic polyurethane macromolecular chain is synthesized through a polyurethane pressure-sensitive adhesive and serves as a macromolecular emulsifier for further free radical emulsion polymerization, free radical polymerization monomers spontaneously migrate into polyurethane micelles due to the hydrophobicity of the free radical polymerization monomers, polymerization is initiated under the action of an initiator, and the hydrophilic polyurethane pressure-sensitive adhesive is obtained. And finally, the core-shell structure composite microsphere with the characteristic of'rigid core at flexible shell 'is formed. According to the invention, the production process is simplified, and chromatic aberration is eliminated; and the silane coupling agent can be used for replacing a silane coupling agent, so that the problem of insufficient durability is further solved, simplification and batch production of the production process can be effectively realized, and meanwhile, the requirements of modern industry on economic and green production can be met.

Description

Technical Field

[0001] The technical solution of the present invention relates to the field of fluorine-free water repellents for textiles, and in particular to a preparation method of a core-shell fluorine-free superhydrophobic emulsion based on the adhesion of polyurethane pressure-sensitive adhesive. Background Art

[0002] Currently, the textile waterproof industry is facing dual challenges of functional upgrading and sustainable development. In recent years, the superhydrophobic effect has become the ultimate pursuit in the field of waterproofing. By analyzing the bionic superhydrophobic technology on the lotus leaf surface, its micro-nano structure and low surface energy characteristics, through the bionic simulation of the multi-level structure of the wax micro-nano papillae on the lotus leaf surface, the core principle of "structure-chemistry" synergistically achieving superhydrophobicity is revealed. The bionic superhydrophobic coating technology developed accordingly mainly includes two approaches: one is the chemical modification route, using low surface energy substances such as fluorinated compounds, long-chain alkanes or siloxanes for surface modification, and achieving hydrophobic effects by reducing the surface free energy of materials; the other is the structure construction route: forming a lotus leaf-like micro-nano composite structure on the substrate surface through nanoparticles such as silica and titanium dioxide, and enhancing the hydrophobic performance by geometric effects; the synergistic effect of the two can endow materials with excellent superhydrophobic properties.

[0003] In the development process of superhydrophobic materials, per- and polyfluoroalkyl substances (PFAS) once occupied an important position due to their unique properties - achieving a long-lasting hydrophobic effect by reducing the surface energy, and being widely used in fields such as waterproof finishing. However, the half-life of these "forever chemicals" is up to hundreds of years, and the detection rate in human blood and breast milk has been increasing year by year. The European Union has completely banned the use of PFAS in textiles in 2023 (Ateia M, Scheringer M, From “forever chemicals” to fluorine-free alternatives[J]. Science, 2024, 385(6706), 256 - 258.). In recent years, many countries and international organizations around the world have been increasingly strict in the control of PFAS. The textile industry needs to actively respond to this trend and is undergoing an iterative upgrade from a fluorinated system to a fluorine-free system (Wei Lihua, Wang Didi, Liu Qi, et al. Product standards and detection status of per- and polyfluoroalkyl compounds in textiles in China[J]. China Fiber Inspection, 2024(5)). At the same time, traditional coatings have poor hydrophobic performance, are easy to wear, are selective to substrates, have complex processes, high costs, and may also release harmful chemical substances. Currently, in fields such as outdoor clothing, medical protective clothing, and industrial fabrics, more stringent requirements are put forward for the waterproof performance of materials: achieving long-lasting and stable superhydrophobic performance of textiles without reducing the fiber properties, and having a simple process finishing and controllable costs.

[0004] To solve the above technical problems, Patent CN118127822A discloses a preparation method of a fluorine-free environmentally friendly superhydrophobic textile. This method is based on a simple dip-coating process and utilizes the strong adhesion of polydopamine (PDA) to achieve a strong adhesion of microspheres on the fiber surface. Similarly, the research team led by Researcher Zhao Lizhong of Hangzhou Dianzi University uses SiO2 particles as the nanostructure and PDA as the binder to prepare core-shell nanospheres SiO2@PDA to construct strong superhydrophobicity. Through the covalent interaction between PDA and polyurethane, it has strong adhesion. This coating is versatile and can be extended to various substrates through self-assembly to achieve superhydrophobicity, but it is difficult to get rid of the color difference problem caused by PDA (Shi Z, Zeng H, Yuan Y, Shi N, Wen L, Rong H, Zhu D, Hu L, Ji L, Zhao L, Zhang X, Constructing superhydrophobicity by self-assembly of SiO2@polydopamine core-shell nanospheres with robust oil-water separation efficiency and anti-corrosion performance[J]. Advanced Functional Materials, 2023, 33(16), 2213042.).

[0005] In addition, Patent CN118127830A discloses a preparation method of a fluorine-free superhydrophobic temperature-adjustable textile. This method prepares an adhesive phase-change microsphere emulsion through emulsion polymerization combined with oxidative self-polymerization, and combines a fluorine-free water repellent to obtain a fluorine-free superhydrophobic temperature-adjustable textile through a two-step padding-drying process. However, the alkaline environment during the oxidative self-polymerization of dopamine in the phase-change microsphere emulsion will affect the emulsion stability, and the color of the phase-change microsphere emulsion wrapped with polydopamine is usually dark brown or black, resulting in color change of the fabric before and after treatment, and the preparation process is complex, with a polymerization time as long as 24h. Patent CN119593209A obtains polymer microspheres through free radical copolymerization or polycondensation of polymer monomers and polymerizable silane coupling agents, and utilizes the silanol group compounds formed by the hydrolysis of silane coupling agents to interact with the surface of the fiber substrate to enhance the adhesion of the microspheres on the fiber surface. However, the surface groups of the microspheres are limited, the attachment points on the fiber surface are limited, the adhesion is insufficient, and the emulsifier on the microsphere surface causes a slight decrease in hydrophobicity.

[0006] In summary, although traditional pure superhydrophobic coatings have a low surface energy, their mechanical strength is low and their adhesion is poor. Summary of the Invention

[0007] The object of the present invention is to provide a preparation method of a core-shell fluorine-free superhydrophobic emulsion based on the adhesiveness of polyurethane pressure-sensitive adhesive in view of the deficiencies of the prior art. This method adopts the seed emulsion polymerization one-pot method. Through the currently used polydopamine in polyurethane pressure-sensitive adhesive, a hydrophilic polyurethane macromolecular chain is synthesized based on the principle of step polymerization reaction, and it is used as a macromolecular emulsifier for further free radical emulsion polymerization. Due to its hydrophobicity, the free radical polymerization monomer spontaneously migrates to the inside of the polyurethane micelle and initiates polymerization under the action of an initiator, ultimately forming a core-shell structure composite microsphere characterized by "rigid core @ flexible shell". The present invention not only simplifies the production process (combining two steps into one), but also eliminates color difference; it can also be used to replace silane coupling agents to further solve the problem of insufficient durability, effectively realizing the simplification and batch production of the production process, and at the same time meeting the requirements of modern industry for economical and green production.

[0008] The technical solution adopted by the present invention is as follows:

[0009] A preparation method of a core-shell fluorine-free superhydrophobic emulsion based on the adhesiveness of polyurethane pressure-sensitive adhesive, the method comprising the following steps:

[0010] Mix emulsion A and emulsion B to obtain a core-shell fluorine-free superhydrophobic emulsion based on the adhesiveness of polyurethane pressure-sensitive adhesive;

[0011] Among them, the mass ratio of emulsion A to emulsion B is 1:0.1 to 100;

[0012] The preparation method of the said emulsion A comprises the following steps:

[0013] Mix the isocyanate group monomer and the oligomeric alcohol monomer and pre-polymerize at 60-120 °C for 2-6 h, then add a hydrophilic chain extender for chain extension reaction for 2-7 h to obtain a prepolymer; then cool down to 30-80 °C, add a neutralizing agent to adjust the pH value to 3-12, and emulsify with deionized water under stirring for 0.2-1 h until the emulsion color is light blue or milky white, then add a free radical polymerization monomer, and then dropwise add an aqueous solution of an initiator, and then polymerize the monomer for 3-24 h to finally form an emulsion A with a core-shell structure with polyurethane as the shell and rigid polymer microspheres as the core;

[0014] Among them, the molar ratio of the isocyanate group monomer to the oligomeric alcohol monomer is 20-0.5:1; the molar ratio of the hydrophilic chain extender to the isocyanate group monomer is 0.2-20:1; the addition amount of the initiator is 0.02-10% of the mass of the free radical polymerization monomer; the mass ratio of the free radical polymerization monomer to the prepolymer is 10-0.1:20;

[0015] The mass fraction of the aqueous solution of the initiator is 0.1-5%; the dropping time of the aqueous solution of the initiator is 0.1-2 h; the mass of deionized water is 0.5-10 times the total mass of the prepolymer;

[0016] The stirring rate is 300 - 5000 rpm;

[0017] The isocyanate monomer is one or more of isophorone diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate;

[0018] The oligomeric alcohol monomer is one or more of polyether polyol, polyester polyol, tetramethylene ether glycol, polyethylene glycol, polypropylene glycol, polyester amide, acrylic polyol, castor oil - based polyol, polydimethylsiloxane, polycarbonate diol;

[0019] The hydrophilic chain extender is one or more of dimethylolpropionic acid, sodium 2 - aminoethanesulfonate, diethylenetriamine, N - methyldiethanolamine;

[0020] The neutralizer is one or more of triethylamine, ammonia water, sodium hydroxide, hydrochloric acid, acetic acid, epichlorohydrin;

[0021] The radical polymerization monomer is one or more of styrene, ethyl acrylate, n - butyl acrylate, lauryl acrylate, 2 - ethylhexyl acrylate, lauryl methacrylate, n - octyl methacrylate, 2 - hydroxyethyl acrylate, 2 - hydroxypropyl acrylate, 2 - hydroxyethyl methacrylate, 2 - hydroxypropyl methacrylate, glycidyl methacrylate, acrylamide, N - hydroxymethylacrylamide, diacetone acrylamide, ethyl acetoacetate methacrylate, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, divinylbenzene, γ - methacryloxypropyltrimethoxysilane;

[0022] The initiator includes one or more of benzoyl peroxide, azobisisobutyronitrile (AIBN), azobisisoheptonitrile, potassium persulfate, ammonium persulfate, tert - butyl peroxybenzoate, tert - butyl hydroperoxide, cumene hydroperoxide;

[0023] The molecular weight of the polyurethane macromolecular emulsifier is 300 - 20000;

[0024] The particle size of the core - shell structure emulsion A with a polyurethane shell and rigid polymer microspheres as the core is 30 - 1000 nm; the mass fraction of the polymer microspheres is 5 - 40%;

[0025] The preparation method of the emulsion B:

[0026] Mix the fluorine - free waterproofing agent and the blocked isocyanate cross - linker, and dilute it with deionized water into a low - concentration fluorine - free waterproofing agent emulsion, namely emulsion B;

[0027] The closed isocyanate crosslinking agent is specifically one of phenol-based isocyanate crosslinking agent, ethanol-based isocyanate crosslinking agent, caprolactam-based isocyanate crosslinking agent, methyl ethyl ketone oxime-based isocyanate crosslinking agent, and sodium bisulfite-based isocyanate crosslinking agent;

[0028] The mass ratio of the fluorine-free water repellent to the blocked isocyanate crosslinking agent is 1:0.01 to 1;

[0029] The fluorine-free water repellent is one or several of silicone water repellents, polyurethane water repellents, and acrylate water repellents;

[0030] The mass fraction of the polymer in the fluorine-free water repellent is 10-80%;

[0031] The mass fraction of the polymer in the low-concentration fluorine-free water repellent emulsion is 0.2-5%;

[0032] The application of the core-shell fluorine-free superhydrophobic emulsion based on the adhesiveness of polyurethane pressure-sensitive adhesive prepared by the method includes the following steps:

[0033] Immerse the fabric in the core-shell fluorine-free superhydrophobic emulsion based on the adhesiveness of polyurethane pressure-sensitive adhesive for 1-100 s, then roll it with a rolling machine under a pressure of 0.1-10 MPa and a vehicle speed of 1-80 m / min, and carry out high-temperature setting at 120-180 °C for 30-600 s to obtain a fluorine-free superhydrophobic textile;

[0034] The fabric can be one of cotton, acrylic, polyester, aramid, spandex, nylon, vinylon, polypropylene, non-woven fabric or a blended fabric.

[0035] The substantial features of the present invention are:

[0036] In the preparation of the currently disclosed polymer microsphere emulsion, the strong adhesion of polymer microspheres on the fiber surface is achieved by coating the surface of the microspheres with polydopamine with strong adhesion, or the silanol-based compound formed by the hydrolysis of the silane coupling agent is used to interact with the surface of the fiber substrate to enhance the adhesion of the microspheres on the fiber surface. However, the former causes color change of the fiber fabric due to the black-brown polydopamine, and the latter has insufficient adhesion due to few attachment sites;

[0037] The present invention provides a method for preparing a fluorine-free superhydrophobic emulsion by combining a core-shell polymer microsphere emulsion with a "rigid core @ flexible shell" structure and a fluorine-free water repellent. Its essential features include: a polyurethane pressure-sensitive adhesive polymer microsphere emulsion (emulsion A) and a water repellent emulsion (emulsion B). Emulsion A and fibers together provide a firm micro-nano structure. The core-shell polymer microsphere with crosslinkable functional groups on the surface and having pressure-sensitive adhesive properties has the following structural characteristics: the shell layer is a polyurethane polymer containing crosslinkable functional groups and having pressure-sensitive adhesive properties, and the core is a rigid polymer microsphere. Its preparation characteristics are as follows: based on the step polymerization mechanism, a polyurethane prepolymer is prepared. After being neutralized by a neutralizing agent, a polyurethane molecular chain containing hydrophilic groups is used as a macromolecular emulsifier for free radical emulsion polymerization. Due to its hydrophobic property, the free radical polymerization monomer enters the interior of the polyurethane emulsion micelles. Then, an initiator is added to initiate the polymerization of the monomer, and a "rigid core @ flexible shell" core-shell polymer microsphere emulsion A with reactive and pressure-sensitive adhesive properties is prepared. Emulsion B is a certain proportion of fluorine-free water repellent and blocked isocyanate crosslinking agent that can provide low surface energy.

[0038] The beneficial effects of the present invention are as follows:

[0039] The textiles treated with the fluorine-free superhydrophobic emulsion provided by the present invention have excellent waterproofing effects and waterproof durability: (1) the shell layer with pressure-sensitive adhesive properties can make the microspheres evenly adhere to the fiber surface during the padding stage; (2) the rigid core can ultimately provide a superhydrophobic rough structure; (3) the functional groups introduced into the shell layer can further react with isocyanate crosslinking agents at high temperatures to firmly anchor between the core-shell microspheres and between the microspheres and the fibers, enhancing the stability of the rough structure; (4) the low surface energy water repellent coating covers the microspheres and fibers and is crosslinked and cured through isocyanate crosslinking agents. The low surface energy and the micro-nano structure provided by the microspheres and fibers together endow the fibers with superhydrophobic properties. For example, the superhydrophobic polyester taffeta textiles prepared in Example 1 can withstand 35 laundering cycles, which is 20% higher than that of the patent CN118127830A of this research group and 75% higher than that of the patent CN119593209A of this research group.

[0040] The pressure-sensitive adhesive core-shell structure polymer microspheres with a "rigid core @ flexible shell" composite structure in emulsion A of the present invention have super strong adhesive properties on acrylic, polyester, aramid, spandex, nylon, vinylon, polypropylene, non-woven fabrics or blended fabrics, which can effectively solve the problem that the existing water repellents only have waterproof effects on single fabrics and have poor versatility.

[0041] Both emulsion A and emulsion B in the present invention are fluorine-free waterborne emulsions, which are environmentally friendly.

[0042] Emulsion A and emulsion B in the present invention can be adjusted to different ratios and concentrations according to different application scenarios, with strong adaptability and controllable costs.

[0043] In the present invention, emulsion A and emulsion B are used in combination, which can provide excellent superhydrophobic performance, strong washing resistance while ensuring the softness, breathability and comfort of fabrics, and can effectively solve the problems such as scratch marks caused by existing waterproof agents, hard hand feeling, and no effect of air drying. Description of the Drawings

[0044] Figure 1 It is a scanning electron microscope photograph of polymer microspheres with a "rigid core @ flexible shell" core-shell structure based on the adhesiveness of polyurethane pressure-sensitive adhesive prepared in Example 1 of the present invention. Among them, Figure 1 (a) is a scanning electron microscope photograph of a "polystyrene @ polyurethane" core-shell structure at room temperature; Figure 1 (b) is a scanning electron microscope photograph of a "polystyrene @ polyurethane" core-shell structure at high temperature.

[0045] Figure 2 It is a scanning electron microscope photograph of the treated polyester textile in Example 1 of the present invention. Detailed Embodiments

[0046] In order to enable those skilled in the art to accurately understand and implement the technical solutions of the present invention, specific embodiments and the accompanying drawings are specifically explained. It should be particularly noted that the embodiments listed herein are only exemplary embodiments for explaining the technical principles and in no way limit the protection scope of the present invention. Based on the technical features defined in the claims of the present invention, equivalent replacements, process parameter adjustments and material improvements made by those skilled in the art through conventional experimental means without departing from the core concept of the present invention should all be covered within the protection scope of the present invention.

[0047] Example 1:

[0048] (1) Emulsion A: 4.45 g of isophorone diisocyanate (i.e., 20.00 mmol) and 10 g of tetramethylene ether glycol (molecular weight 1000 g / mol, i.e., 10.00 mmol) were pre-polymerized at 60 °C for 4 h in a molar ratio of 2:1, and then 0.9 g of dimethylolpropionic acid (i.e., 6.71 mmol) was added for chain extension for 3 h to obtain a prepolymer; after neutralization to pH = 8 with 0.25 g of 28% ammonia water, 50 g of deionized water was added for emulsification to milky white (a polyurethane molecular chain containing hydrophilic groups was used as a macromolecular emulsifier) to obtain a cationic aqueous polyurethane; 7.5 g of styrene and 2.5 g of divinylbenzene (due to its hydrophobic property, it entered the interior of the polyurethane latex particles for polymerization) were swollen into the prepared cationic aqueous polyurethane emulsion containing hydrophilic groups, and then a mixed solution of 0.05 g of potassium persulfate and 10 g of deionized water was added dropwise over 0.5 h, and the monomers were polymerized for 8 h to obtain a preparation method of a core-shell fluorine-free superhydrophobic emulsion based on polyurethane pressure-sensitive adhesive viscosity with a mass fraction of 29.6%;

[0049] (2) Emulsion B: After mixing 3 g of a 30% organosilicon waterproofing agent (commercial product) and 0.5 g of a 30% methyl ethyl ketoxime-type blocked isocyanate crosslinking agent, 46.5 mL of deionized water was added for dilution to obtain a fluorine-free waterproofing agent emulsion with a mass fraction of 2.1%;

[0050] (3) After uniformly mixing 1 g of Emulsion A and 50 g of Emulsion B, a polyester fabric (25×25 cm) was first immersed in the mixed solution for 10 s, then the nip roll pressure was 0.4 MPa, the vehicle speed was 6.5 m / min, and it was dried at 150 °C for 60 s to obtain a fluorine-free superhydrophobic polyester textile based on polyurethane pressure-sensitive adhesive viscosity.

[0051] Figure 1 Scanning electron microscope photos of the polymer microspheres with a "rigid core@flexible shell" core-shell structure based on polyurethane pressure-sensitive adhesive viscosity prepared in Example 1 of the present invention under (a) normal temperature and (b) 160 °C high temperature conditions. At normal temperature, due to the glass transition temperature of the outer shell being greater than normal temperature, there was no adhesion between the microspheres, and they had a clear spherical contour; after high-temperature heating, the outer polyurethane molecular chains were entangled with each other and adhered to form an "island" structure. This structural change at different temperatures indicated that the polymer microspheres prepared in Example 1 of the present invention had a "rigid core@flexible shell" core-shell structure. Without the core-shell structure, it would all melt after heating to form a film and would not present this "island structure".

[0052] Figure 2 Scanning electron microscope photo of the polyester textile after being treated in Example 1. For the treated polyester fabric, the rigid microspheres were evenly and densely distributed on the fiber surface, having an obvious rough structure.

[0053] Table 1 shows the test data of the hydrophobicity of the polyester fabric treated in Example 1, its wash resistance, hand feel, and hand scratch resistance in the hanging-dry and tumble-dry states. Different from the traditional direct use of nanoparticles, this method utilizes nano-microspheres coated with polyurethane-based pressure-sensitive adhesives. The soft segments and hard segments of the adhesives are intertwined, which can not only provide a rough structure (enhancing the superhydrophobic performance) but also ensure strong adhesion (excellent wash resistance), without affecting the hand feel and hand scratch resistance of the fabric.

[0054] Table 1 Details of the test results of the polyester fabric treated in Example 1

[0055]

[0056]

[0057] Example 2:

[0058] A fluorine-free superhydrophobic polyamide textile based on the adhesiveness of polyurethane pressure-sensitive adhesive, the preparation method is the same as that in Example 1, except that: polyamide textile is used instead of polyester textile.

[0059] Example 3:

[0060] A fluorine-free superhydrophobic aramid textile based on the adhesiveness of polyurethane pressure-sensitive adhesive, the preparation method is the same as that in Example 1, except that: aramid textile is used instead of polyester textile.

[0061] Example 4:

[0062] A fluorine-free superhydrophobic spandex textile based on the adhesiveness of polyurethane pressure-sensitive adhesive, the preparation method is the same as that in Example 1, except that: spandex textile is used instead of polyester textile.

[0063] Example 5:

[0064] (1) Emulsion A: 4.45 g of isophorone diisocyanate (i.e., 20.00 mmol) and 10 g of tetramethylene ether glycol (molecular weight of 1000 g / mol, i.e., 10.00 mmol) were pre-polymerized at 60 °C for 4 h according to a molar ratio of 2:1, and then 0.8 g of N-methyldiethanolamine (i.e., 6.71 mmol) was added for chain extension for 3 h. After neutralization to pH = 6 with 0.4 g of acetic acid, 50 g of deionized water was added to emulsify to a milky white color to obtain a cationic aqueous polyurethane; 7.5 g of styrene and 2.5 g of divinylbenzene were swollen into the prepared cationic aqueous polyurethane emulsion containing hydrophilic groups, and then a mixed solution of 0.05 g of potassium persulfate and 10 g of deionized water was added dropwise over 0.5 h, and the monomer polymerization was carried out for 8 h to obtain a fluorine-free superhydrophobic emulsion with a mass fraction of 29.5% based on the adhesiveness of polyurethane pressure-sensitive adhesive;

[0065] (2) Emulsion B: After mixing 3 g of a 30% silicone-based waterproofing agent and 0.5 g of a 30% methyl ethyl ketoxime-blocked isocyanate crosslinking agent, 46.5 mL of deionized water was added for dilution to obtain a fluorine-free waterproofing agent emulsion with a mass fraction of 2.1%.

[0066] (3) After uniformly mixing 1 g of Emulsion A and 50 g of Emulsion B, a polyester fabric (25×25 cm) was first immersed in the mixed solution for 10 s, with a nip roll pressure of 0.4 MPa and a vehicle speed of 6.5 m / min, and then dried at 150 °C for 60 s to obtain a fluorine-free superhydrophobic polyester textile based on the adhesiveness of polyurethane pressure-sensitive adhesive.

[0067] Example 6:

[0068] A fluorine-free superhydrophobic polyamide textile based on the adhesiveness of polyurethane pressure-sensitive adhesive was prepared in the same way as in Example 5, except that a polyamide textile was used instead of a polyester textile.

[0069] Example 7:

[0070] A fluorine-free superhydrophobic aramid textile based on the adhesiveness of polyurethane pressure-sensitive adhesive was prepared in the same way as in Example 5, except that an aramid textile was used instead of a polyester textile.

[0071] Example 8:

[0072] A fluorine-free superhydrophobic spandex textile based on the adhesiveness of polyurethane pressure-sensitive adhesive was prepared in the same way as in Example 5, except that a spandex textile was used instead of a polyester textile.

[0073] As can be seen from the above examples, the present invention prepares a hydrophilic macromolecular polyurethane chain based on the principle of step polymerization, uses this hydrophilic macromolecular chain as a macromolecular emulsifier, and the free-radical polymerization monomers enter the interior of the polyurethane latex particles for polymerization due to their hydrophobicity, finally forming a "rigid core@flexible shell" polymer microsphere emulsion with a core-shell structure. By adopting the dip-roll-dry process, a variety of fluorine-free superhydrophobic textiles have been successfully prepared. This method not only ensures excellent superhydrophobicity and washability, but also has the characteristics of environmental friendliness, easy large-scale production, and wide applicability.

[0074] Matters not covered in the present invention are well-known technologies.

Claims

1. A preparation method of a core-shell fluorine-free superhydrophobic emulsion based on the adhesiveness of polyurethane pressure-sensitive adhesive, characterized in that the method comprises the following steps: Mix emulsion A and emulsion B to obtain a core-shell fluorine-free superhydrophobic emulsion based on the adhesiveness of polyurethane pressure-sensitive adhesive; Among them, The mass ratio of emulsion A to emulsion B is 1:0.1 - 100; The preparation method of the said emulsion A comprises the following steps: Mix the isocyanate group monomer and the oligomeric alcohol monomer, and pre-polymerize at 60 - 120 °C for 2 - 6 h, then add a hydrophilic chain extender for chain extension reaction for 2 - 7 h to obtain a prepolymer; then cool down to 30 - 80 °C, add a neutralizer to adjust the pH value to 3 - 12, and emulsify with deionized water under stirring for 0.2 - 1 h until the emulsion color is light blue or milky white, then add a free radical polymerization monomer, and then dropwise add an aqueous solution of an initiator, and then polymerize the monomer for 3 - 24 h to finally form a core-shell structure emulsion A with polyurethane as the shell and rigid polymer microspheres as the core; Among them, the molar ratio of the isocyanate group monomer to the oligomeric alcohol monomer is 20 - 0.5:1; the molar ratio of the hydrophilic chain extender to the isocyanate group monomer is 0.2 - 20:1; the addition amount of the initiator is 0.02 - 10% of the mass of the free radical polymerization monomer; the mass ratio of the free radical polymerization monomer to the prepolymer is 10 - 0.1:20; The mass of deionized water is 0.5 - 10 times the total mass of the prepolymer; The said isocyanate monomer is one or more of isophorone diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate; The said oligomeric alcohol monomer is one or more of polyether polyol, polyester polyol, tetramethylene ether glycol, polyethylene glycol, polypropylene glycol, polyester amide, acrylic polyol, castor oil-based polyol, polydimethylsiloxane, polycarbonate diol; The said hydrophilic chain extender is one or more of dimethylolpropionic acid, sodium 2-aminoethanesulfonate, diethylenetriamine, N-methyldiethanolamine; The said neutralizer is one or more of triethylamine, ammonia water, sodium hydroxide, hydrochloric acid, acetic acid, epichlorohydrin; The said free radical polymerization monomer is one or more of styrene, ethyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, lauryl methacrylate, n-octyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, acrylamide, N-hydroxymethylacrylamide, diacetone acrylamide, ethyl acetoacetate methacrylate, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, divinylbenzene, γ-methacryloxypropyltrimethoxysilane; The said initiator includes one or more of benzoyl peroxide, azobisisobutyronitrile (AIBN), azobisisoheptonitrile, potassium persulfate, ammonium persulfate, tert-butyl peroxybenzoate, tert-butyl hydroperoxide, cumene hydroperoxide; The preparation method of the said emulsion B: Mix the fluorine-free water repellent with a blocked isocyanate crosslinking agent, and dilute it with deionized water into a low-concentration fluorine-free water repellent emulsion, namely Emulsion B; The specific blocked isocyanate crosslinking agent is one of a phenol-type isocyanate crosslinking agent, an ethanol-type isocyanate crosslinking agent, a caprolactam-type isocyanate crosslinking agent, a methyl ethyl ketone oxime-type isocyanate crosslinking agent, and a sodium bisulfite-type isocyanate crosslinking agent; The mass ratio of the fluorine-free water repellent to the blocked isocyanate crosslinking agent is 1:0.01 to 1; The fluorine-free water repellent is one or several of a silicone water repellent, a polyurethane water repellent, and an acrylate water repellent.

2. The preparation method of the core-shell fluorine-free superhydrophobic emulsion based on the adhesiveness of polyurethane pressure-sensitive adhesive is characterized in that, The mass fraction of the aqueous solution of the initiator is 0.1 to 5%; the dropping time of the aqueous solution of the initiator is 0.1 to 2 h.

3. The preparation method of the core-shell fluorine-free superhydrophobic emulsion based on the adhesiveness of polyurethane pressure-sensitive adhesive is characterized in that, The stirring rate is 300 to 5000 rpm.

4. The preparation method of the core-shell fluorine-free superhydrophobic emulsion based on the adhesiveness of polyurethane pressure-sensitive adhesive is characterized in that, The molecular weight of the polyurethane macromolecular emulsifier is 300 to 20000.

5. The preparation method of the core-shell fluorine-free superhydrophobic emulsion based on the adhesiveness of polyurethane pressure-sensitive adhesive, characterized in that, The particle size of the core-shell structured Emulsion A with a polyurethane shell and rigid polymer microspheres as the core is 30 to 1000 nm; the mass fraction of the polymer microspheres is 5 to 40%.

6. The preparation method of the core-shell fluorine-free superhydrophobic emulsion based on the adhesiveness of polyurethane pressure-sensitive adhesive is characterized in that, The mass fraction of the polymer in the fluorine-free water repellent is 10 to 80%; The mass fraction of the polymer in the low-concentration fluorine-free water repellent emulsion is 0.2 to 5%.

7. Use of the core-shell fluorine-free superhydrophobic emulsion based on the adhesiveness of polyurethane pressure-sensitive adhesive prepared by the method according to claim 1, characterized in that, It includes the following steps: Immerse the fabric in the core-shell fluorine-free superhydrophobic emulsion based on the adhesion of the polyurethane pressure-sensitive adhesive for 1 to 100 s, then roll it with a rolling machine under a pressure of 0.1 to 10 MPa and a vehicle speed of 1 to 80 m / min, and perform high-temperature setting at 120 to 180 °C for 30 to 600 s to obtain a fluorine-free superhydrophobic textile; The fabric can be one of cotton, acrylic, polyester, aramid, spandex, nylon, vinylon, polypropylene, non-woven fabric or a blended fabric.

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