Production method of super-hydrophobic composite base cloth and easy-folding umbrella

Abstract

A super-hydrophobic composite base cloth production method and an easy-folding umbrella belong to the field of textile processing technology, comprising the following steps: step S1, preparation of a polyester surface layer; step S2, preparation of a waterproof fiber membrane; the waterproof fiber membrane is prepared by electrospinning, and the raw materials include styrene-acrylonitrile copolymer and double solvent; the double solvent is a good solvent for styrene-acrylonitrile copolymer; step S3, lamination: the woven fabric is used as the inner layer, the waterproof fiber membrane is used as the middle layer, and the polyester surface layer is used as the outer layer, and lamination and ironing are carried out to form a composite base cloth. The umbrella is double-warp woven, the yarn gap is increased, the physical space is reserved for the pre-folding mark, and the regular folding mark is formed through hot pressing and setting. When it is folded, it can be stored and shaped along the folding mark, and the durable water-repellent effect is realized through the micro-nano rough structure of the waterproof fiber membrane.

Description

Technical Field

[0001] This invention belongs to the field of textile processing technology, specifically relating to a method for producing a superhydrophobic composite base fabric and an easy-folding umbrella. Background Technology

[0002] Traditional umbrella fabrics (such as nylon and polyester) offer some water resistance, but their hydrophobic properties are insufficient, leading to water residue, a damp canopy, and inconvenient storage. For example, Chinese patent CN107190508A discloses a water-repellent fabric and an umbrella made from it. The fabric is a high-density plain-weave fabric woven from ultra-fine polyester fibers, with a hydrophobic coating on the surface. While it provides basic water resistance, its hydrophobic properties are limited by the material's surface chemical properties and microstructure, resulting in the following problems:

[0003] 1. Insufficient hydrophobicity: The contact angle of traditional coatings is usually less than 120° (the contact angle of coated fabrics on the smooth solid surface with the lowest surface energy can only be increased to 120° at most), which easily leads to rainwater sticking to the wall.

[0004] 2. Lack of self-cleaning ability: Traditional coatings cannot form a micro-nano rough structure similar to lotus leaves; dust easily floats on the umbrella surface, requiring regular cleaning.

[0005] Meanwhile, traditional folding umbrellas rely on manual folding of the canopy, which easily leads to messy creases and fabric deformation. Therefore, it is necessary to develop an umbrella fabric that is superhydrophobic while also facilitating umbrella folding. Summary of the Invention

[0006] In view of the above-mentioned problems in the existing technology, the first objective of the present invention is to provide a method for producing superhydrophobic composite substrate fabric.

[0007] A second objective of this invention is to provide an umbrella manufactured using the above-described preparation process.

[0008] The present invention achieves its objective through the following technical solutions.

[0009] A method for producing a superhydrophobic composite substrate fabric includes the following steps:

[0010] Step S1, preparation of the polyester surface layer;

[0011] Step S2, preparation of the waterproof fiber membrane; the waterproof fiber membrane is prepared by electrospinning, and its raw materials include styrene-acrylonitrile copolymer and a two-component solvent; the two-component solvent is a good solvent for styrene-acrylonitrile copolymer; the two-component solvent consists of a low-boiling-point non-water-soluble first solvent and a high-boiling-point hydrophilic second solvent, and the volume ratio of the first solvent to the second solvent is (7-9):(1-3); the boiling point of the first solvent is below 133℃; the boiling point of the second solvent is above 146℃;

[0012] Step S3, Lamination: The woven fabric is used as the inner layer, the waterproof fiber membrane as the middle layer, and the polyester surface layer as the outer layer. The layers are laminated and ironed to form a composite base fabric.

[0013] Further, step S1 includes:

[0014] Step S101, weaving: both warp and weft yarns are made of 30D / 48F polyester textured network yarn, which is woven on a loom to obtain polyester grey fabric; the polyester grey fabric has a basic unit of double warp and double weft; the arrangement pattern of the warp yarns is: synchronous two up and two down, that is, two adjacent warp yarns float synchronously on two weft yarns, and then the next two weft yarns sink synchronously.

[0015] Step S102, Pre-shrinking: The polyester fabric is pre-shrinked using a pre-shrinking machine to remove residual tension, followed by rinsing and dewatering;

[0016] Step S103, Water-repellent pretreatment: Impregnate the polyester fabric with a water-repellent finishing agent and dry it.

[0017] Further, step S2 includes:

[0018] Step S201, preparing the electrospinning solution: Styrene-acrylonitrile copolymer is used as the polymer solute and mixed with a two-element solvent. Then tetrabutylammonium perchlorate is added. The mixture is then placed on a heating stirrer and heated and stirred until it becomes clear and transparent to obtain the electrospinning solution. The electrospinning solution is then allowed to stand and cool to room temperature.

[0019] Step S202, set the electrospinning experiment parameters:

[0020] Step S203: Perform electrospinning, collect the electrospun fibers, and take out a waterproof fiber membrane with a thickness of about 200 μm.

[0021] Furthermore, in step S201, the concentration of the styrene-acrylonitrile copolymer is 300~375 mg / mL; the concentration of tetrabutylammonium perchlorate is not greater than 2.5 mg / mL; the heating and stirring conditions are: heating temperature 65℃ and stirring for 12 hours; the first solvent is chloroform or chlorobenzene; the second solvent is dimethyl sulfoxide or N,N-dimethylformamide.

[0022] Furthermore, in step S202, the feed flow rate is set to 1.5 mL / h; the voltage is set to 10.9 kV; the working distance is set to 19 cm; the temperature is controlled at 23-28℃; and the ambient relative humidity is controlled at approximately 60% RH.

[0023] Further, step S3 includes:

[0024] Step S301, Inner layer pretreatment:

[0025] First, sprinkle ethylene-vinyl acetate copolymer powder onto the upper surface of the woven fabric, at a rate of 12-15 g / m². 2 Preheat the inner layer at a temperature of 120-125℃ for 2-2.5 minutes to allow the ethylene-vinyl acetate copolymer powder to initially bond with the woven fabric, preventing it from spilling during subsequent processing.

[0026] Step S302, outer layer pretreatment;

[0027] Then, polytetrafluoroethylene nanoparticles with an average particle size of approximately 50 nm are sprinkled onto the waterproof fiber membrane at a rate of 12-15 g / m². 2 The polyester surface layer is covered on the surface of the waterproof fiber membrane and then heated and dried at a temperature of 90~95℃ for 3~3.5 minutes.

[0028] Step S303, three-layer composite lamination:

[0029] Next, the dried waterproof fiber membrane bottom layer is covered on the upper surface of the woven fabric to form a composite base fabric, and then laminated and ironed. The ironing temperature is 130~135℃, the ironing time is 5~5.5min, and the pressure is 0.4~0.5MPa.

[0030] Step S304, gradient curing and shaping:

[0031] Finally, the composite base fabric is dried in an oven at 80°C for 1 hour, then at 50°C for 2 hours, and then air-cooled at 20°C for 3 minutes.

[0032] A method for producing a superhydrophobic composite base fabric further includes step S4, molding creases: using a molding process, the composite base fabric is folded at a specified position, a pressure of 5~8MPa is applied, and an electric heating film is heated to 110~120℃; the pressure holding time is 90~120 seconds to form creases.

[0033] A foldable umbrella, the canopy of which is made of the aforementioned composite base fabric.

[0034] This design employs a double-ply warp and weft weave, with the warp and weft yarns interwoven in a plain weave to form a double-warp, double-weft basic unit. Compared to the traditional 1:1 warp and weft interweaving structure, while maintaining tear resistance, the double-ply yarn offers better guidance and lower bending resistance, providing a physical buffer for subsequent heat-pressing folding and mitigating plastic deformation caused by excessive fiber compression. After heat-pressing and shaping, the umbrella can fold regularly along pre-set creases during storage, ensuring a flat canopy and preventing deformation.

[0035] In this design, the umbrella fabric is a composite base fabric. Through material property optimization, it is endowed with excellent hydrophobic properties, ensuring that rainwater quickly slides off after contact, effectively preventing water droplets from lingering on the surface or forming a sticky residue. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the warp yarn arrangement pattern;

[0037] Figure 2 This is a SEM image of the fiber cross-section from Example 1;

[0038] Figure 3 This is a water contact angle profile diagram of Example 1;

[0039] Figure 4 This is a SEM image of the fiber cross-section from Example 2;

[0040] Figure 5 This is a SEM image of the fiber cross-section from Example 3;

[0041] Figure 6 This is a SEM image of the fiber cross-section from Example 4;

[0042] Figure 7 This is a SEM image of the fiber cross-section from Example 5;

[0043] Figure 8 This is a SEM image of the fiber cross-section of Example 6. Detailed Implementation

[0044] The technical solution of the present invention will now be clearly and completely described in conjunction with the accompanying drawings.

[0045] Superhydrophobic fabric technology, by constructing micro-nano rough structures, may break through the performance bottlenecks of traditional umbrellas. Superhydrophobic fabrics, such as GORE-TEX, are generally used in the form of thin-film linings in rain jackets. They are porous films with 1.4 billion micropores per square centimeter, which are 20,000 times smaller than a water droplet, and have excellent water-repellent properties.

[0046] If superhydrophobic fabrics are applied to umbrellas, the hydrophobic properties of the umbrella surface can be increased, and the umbrella surface can be easily spun dry in the case of a small amount of rain. However, superhydrophobic fabrics are mostly laminated fabrics, which have the following drawbacks:

[0047] 1. Superhydrophobic films are usually bonded to umbrella substrates using adhesives such as hot melt adhesives. However, the adhesives may penetrate into the micropores of the superhydrophobic film, compromising its hydrophobicity.

[0048] 2. If the superhydrophobic film is prepared by electrospinning, the production of porous fibers on the surface mostly uses a combination of good and bad solvents. Fibers with pores on the surface can only be obtained under specific conditions: (1) the boiling point of the good solvent must be lower than that of the bad solvent; (2) the good solvent is insoluble in water; (3) the bad solvent is highly polar and soluble in water. For example, Chinese invention application CN112442210A and application number 202010846922.X discloses a method for manufacturing porous bodies of non-water-soluble polymers. It discloses a step of preparing a solution in a mixed solvent containing a good solvent and a bad solvent of the non-water-soluble polymer, wherein the boiling point of the bad solvent is higher than that of the good solvent. The determination of whether a particular solvent is a good or bad solvent relative to a specific polymer can be made using the Hansen solubility parameter (HSP). The boiling point of the good solvent must be lower than that of the bad solvent, which greatly limits the range of solvents that can be selected. Undesirable solvents typically have high boiling points (such as cyclohexanol 161°C and ethylene glycol 244°C), and are difficult to remove from fibers by conventional drying, which may affect the chemical stability or biocompatibility of the superhydrophobic film.

[0049] In this scheme, all solvents are good solvents for polymer solutes, and the controllable generation of fiber pores is achieved through spontaneous phase separation, thereby endowing the fiber with superhydrophobicity.

[0050] A method for producing a superhydrophobic composite base fabric and an easy-folding umbrella, comprising the following steps:

[0051] Step S1, preparation of the polyester surface layer.

[0052] Step S101, weaving: Both warp and weft yarns are made of 30D / 48F polyester textured network yarn (DTY), which is woven on a loom to obtain polyester fabric.

[0053] Figure 1 This is a schematic diagram of the warp yarn arrangement pattern; such as Figure 1 Therefore, polyester grey fabric has a basic unit of double warp and double weft. The basic unit of traditional grey fabric is 1 / 1 warp and weft interlacing. The basic unit of polyester grey fabric in this scheme is 2 / 2 warp and weft interlacing, and the arrangement pattern of the warp yarns is: synchronous two up and two down, that is, two adjacent warp yarns rise synchronously on two weft yarns, and then the next two weft yarns sink synchronously.

[0054] Elasticity and softness: This structure is more symmetrical and balanced, with evenly distributed interlacing points. The float and sink lengths of the warp and weft yarns are equal (both 2), and the gaps between each set of yarns (warp and weft) are increased, so the yarns are not tightly bound.

[0055] Wrinkle resistance: Compared to 2 / 1 twill or 2 / 2 twill weaves, the 2 / 2 warp and weft interweaving in this design is similar to plain weave, featuring a symmetrical structure that is easily resilient. The fabric structure is also looser, allowing the yarns more freedom of movement. When subjected to external force, the yarns can more easily slip, bend, or stretch, and return to their original shape after the force is released.

[0056] The polyester textured network yarn has a fineness of 30D, making the yarn finer and the polyester fabric lighter and softer; the monofilament count is 48F, which is soft, has a delicate surface texture, and good drape.

[0057] To achieve this solution, the loom can be a double warp beam loom that synchronously feeds two sets of warp yarns and adopts a double shed design. Of course, other technical means can also be used to achieve double warp and double weft.

[0058] The basic unit of double warp and double weft allows the polyester fabric to retain its original properties (strength, elasticity, and breathability) while effectively increasing the gap between adjacent yarns (warp and weft), reserving space for creases and forming a pre-crease guide.

[0059] Both warp and weft yarn densities are 85–95 yarns / cm; this avoids overly tight fabric that can cause stiffness and affect the umbrella's folding performance.

[0060] Step S102, Pre-shrinking: The polyester fabric is pre-shrinked using a pre-shrinking machine to remove residual tension, and then rinsed and dehydrated.

[0061] Step S103, Water-repellent pretreatment: Impregnate the polyester fabric with a water-repellent finishing agent and dry it.

[0062] Water-repellent finishing agents can be modified resin-based fluorine-free water-repellent finishing agents (such as the ECORING model from the HOLPOSON brand) or polyurethane-based fluorine-free water-repellent finishing agents (such as the M630 model from the TEXNOLOGY brand), thereby giving the polyester fabric a preliminary water-repellent property.

[0063] Step S2, preparation of waterproof fiber membrane.

[0064] This method uses electrospinning to prepare waterproof fiber membranes, which is easy and simple to manufacture and can produce nanoscale porous fibers.

[0065] Electrospinning: The prepared electrospinning solution is injected into a syringe and propelled at a constant flow rate by a syringe pump to a metal needle. At the needle tip, the solution forms spherical droplets due to surface tension. A high-voltage DC electric field (typically 10–30 kV) is applied to the metal needle, causing surface charges to accumulate and generate electrostatic repulsion. When the electric field exceeds the surface tension and viscoelastic resistance (originating from polymer chain entanglement), the spherical droplets are stretched into a conical structure, known as a Taylor cone. The charged jet ejected from the tip of the Taylor cone is accelerated in the electric field and subjected to the following effects: charge repulsion (continuously stretching the jet), viscoelastic resistance (inhibiting jet breakage), and air turbulence (causing high-frequency helical oscillations in the jet). This process reduces the jet diameter from the micrometer scale to the nanometer scale (typically 50–500 nm). During the jet's movement, the solvent rapidly evaporates (the evaporation rate is controlled by the solvent's boiling point and ambient temperature and humidity), increasing the polymer concentration to the curing point, thus curing the fibers. The cured fibers are deposited on a grounded collection device (such as a flat plate, roller, or disc), forming a nonwoven fiber film.

[0066] Step S201, preparing electrospinning solution: mix the polymer solute with the two solvents, then add tetrabutylammonium perchlorate; then place it on a heating stirrer and heat and stir until clear and transparent to obtain electrospinning solution, and then let the electrospinning solution stand and cool to room temperature.

[0067] In the electrospinning solution, the concentration of the polymer solute is 300~375 mg / mL; the two solvents are both good solvents for the polymer solute, including a low-boiling-point non-water-soluble first solvent and a high-boiling-point hydrophilic second solvent; the volume ratio of the first solvent and the second solvent is (7-9):(1-3); the concentration of tetrabutylammonium perchlorate is not greater than 2.5 mg / mL.

[0068] Furthermore, the heating and stirring conditions are as follows: heating temperature 65℃ and stirring for 12 hours.

[0069] Polymer solute: The length of the polymer chain is determined by its molecular weight. When the concentration of the polymer solute increases, the molecular chain density per unit volume increases, the inter-chain interaction is enhanced, and the solution viscosity increases significantly. If the concentration of the polymer solute increases to a critical value, the polymer chains entangle with each other, stabilizing the jet and reducing droplet formation. The fiber diameter will increase significantly with the increase of polymer concentration. However, when the concentration is too high, in addition to the possibility that the syringe pump may not be able to push it, the excessive entanglement of molecular chains leads to a sharp increase in the viscoelasticity of the solution, making it difficult for the jet to be fully stretched, and the fiber diameter distribution becomes wider and more prone to adhesion.

[0070] In this scheme, the polymer solute is styrene-acrylonitrile copolymer, English name: Poly(styrene-co-acrylonitrile) (SAN). This substance is a thermoplastic plastic, which is copolymerized from two monomers, styrene and acrylonitrile. Its average molecular weight (Mw) is about 165,000 g / mol, and it can be purchased from Sigma-Aldrich.

[0071] Tetrabutylammonium perchlorate: As a highly efficient electrolyte, it can significantly enhance the overall conductivity of the solution, effectively inhibit spindle formation by increasing the surface charge density of the jet, reduce fiber diameter, and improve fiber morphology uniformity; English name: Tetrabutylammonium Perchlorate, TBAP; purity >98%, molecular weight Mw=341.92g / mol, available from Tokyo Chemical Industry Co., Ltd.

[0072] Solvents: The conductivity and boiling point of the solvent both affect the results of electrospinning fibers. High solvent conductivity results in a higher tensile force in the jet, producing finer fibers without spindles. If the solvent conductivity is too low, the droplet surface lacks sufficient charge density to form a stable Taylor cone, leading to beading in the spun fibers and even electrospraying. Boiling point affects the solvent's evaporation rate, primarily influencing fiber diameter. Solvents with higher boiling points evaporate more slowly, allowing for a longer stretching process before jet solidification, resulting in finer fibers. Conversely, solvents with lower boiling points evaporate faster, causing rapid jet solidification and resulting in coarser fibers. In some cases, the surface may be dry, but the fiber interior may not be solidified, and the weak outer polymer shell cannot maintain the fiber's cylindrical shape, ultimately causing the fiber to collapse and flatten.

[0073] In this scheme, both solvents are good solvents for polymer solutes.

[0074] A dual-solvent designation comprises a low-boiling-point, water-insoluble first solvent and a high-boiling-point, hydrophilic second solvent. Further, the standard for the low boiling point of the first solvent is: a boiling point below 133°C. The standard for the high boiling point of the second solvent is: a boiling point above 146°C. Water-insoluble means insoluble in water, with low solubility under normal conditions (25°C, 1 atm), solubility <0.1 g / 100 g water. Hydrophilic means readily soluble in water, with high solubility under normal conditions (25°C, 1 atm), solubility ≥10 g / 100 g water.

[0075] Preferably, the first solvent is chloroform (CF) or chlorobenzene (CB); the second solvent is dimethyl sulfoxide (DMSO) or N,N-dimethylformamide (DMF).

[0076] In the comparative example, the first solvent was methyl isobutyl ketone (MIBK) or 1,1,2,2-tetrachloroethane (TeCA); the second solvent was N,N-dimethylacetamide (DMAc).

[0077] Step S202, setting electrospinning experimental parameters:

[0078] Feed flow rate is set to 1.5 mL / h; S202 voltage is set to 10.9 kV; working distance is set to 19 cm; temperature is controlled at 23-28℃; ambient relative humidity is controlled at approximately 60% RH.

[0079] Feed flow rate: Increasing the feed flow rate leads to an increase in fiber diameter, mainly because the volume of solution flowing out per unit time increases, and the electric field stretching force cannot fully refine the jet. When the flow rate is too low, insufficient solution supply can easily cause jet breakage, forming a spindle structure.

[0080] Voltage: The voltage needs to reach a critical value so that the electrostatic force overcomes the surface tension of the solution, thereby stabilizing the jet from the needle tip and forming a Taylor cone. Increasing the voltage can enhance the electric field stretching force, improve electrospinning stability, and promote fiber diameter refinement. However, excessively high voltage can cause jet whipping instability, leading to multiple jets, a wider fiber diameter distribution, or even a reverse increase in diameter, and even needle tip forking.

[0081] Working distance: When the working distance (distance between needle tip and collecting plate) is too short (e.g., <15cm), the solvent evaporation time is insufficient, and residual solvent when the fiber reaches the collecting plate can easily cause the fiber to redissolve, stick together, or flatten. As the distance increases, the jet flight path lengthens, and the stretching time and solvent evaporation time increase synchronously, which is beneficial for the full refinement of the fiber. However, if the distance is too long (e.g., >20cm), it will weaken the electric field strength, reduce the fiber deposition efficiency, and may cause drift.

[0082] Temperature: Increased temperature accelerates solvent evaporation and reduces the viscosity of the polymer solution. Lower viscosity is beneficial for optimizing molecular chain orientation and promoting fiber diameter reduction; however, accelerated evaporation may shorten curing time. A balance must be struck between these two factors to avoid nozzle clogging. Extremely high temperatures may induce polymer degradation or uneven diameter distribution.

[0083] Relative humidity: Higher relative humidity indicates a higher concentration of water vapor in the environment. In high-humidity electrospinning environments, water vapor acts as a poor solvent, inducing rapid phase separation in hydrophobic polymers. This causes premature fiber precipitation and curing, resulting in increased fiber diameter and a porous surface morphology. Conversely, for hydrophilic polymers, high humidity delays curing, prolongs jet stretching time, and significantly reduces fiber diameter. Humidity needs to be precisely controlled based on the polymer's hydrophilicity / hydrophobicity to optimize morphology.

[0084] Step S203: Perform electrospinning, collect the electrospun fibers, and take out the waterproof fiber membrane, which is about 200 μm thick.

[0085] The method of collecting electrospun fibers can be a rotating drum collector (such as Chinese Patent No. CN102493001A), or aluminum foil substrate pretreatment (such as Chinese Patent No. CN104480639A), or other existing technologies in the field. This solution does not limit the method.

[0086] Step S3, lamination.

[0087] The woven fabric is used as the inner layer, the waterproof fiber membrane as the middle layer, and the polyester surface layer as the outer layer. The layers are then laminated and ironed to form a composite base fabric.

[0088] For woven fabrics, polyester taffeta is the preferred choice. As a lining, polyester taffeta has good shape retention, reducing deformation and wrinkling.

[0089] Step S301, inner layer preprocessing.

[0090] First, sprinkle ethylene-vinyl acetate copolymer (EVA) onto the upper surface of the woven fabric, at a powdering rate of 12-15 g / m². 2 (Preferred 13g / m 2 The inner layer is preheated at 120-125℃ for 2-2.5 minutes to allow the ethylene-vinyl acetate copolymer powder to initially bond with the woven fabric, preventing spillage during subsequent processing. The powder surface melts at 120℃ to form viscous microspheres, which are initially anchored in the gaps between the woven fabric fibers. At the same time, the time is shortened to prevent the woven fabric from aging due to heat.

[0091] Step S302, outer layer preprocessing.

[0092] Then, polytetrafluoroethylene (PTFE) nanoparticles (average particle size approximately 50 nm) are sprinkled onto the waterproof fiber membrane at a rate of 12-15 g / m². 2 The polyester surface layer is covered on the surface of the waterproof fiber membrane and then heated and dried at 90-95℃ for 3-3.5 minutes. The polytetrafluoroethylene nanoparticles have low surface energy and bind to the fiber membrane through transient dipole interaction, filling only the surface pits of the fiber membrane without clogging the internal micropores.

[0093] Step S303, three-layer composite lamination.

[0094] Next, the dried waterproof fiber membrane is applied to the upper surface of the woven fabric to form a composite base fabric, and then laminated and ironed at 130-135℃ for 5-5.5 minutes with a pressure of 0.4-0.5 MPa. At this point, the hot melt adhesive powder is completely melted and has excellent fluidity, penetrating the fiber pores and reaching the non-bonded surface of the woven fabric under pressure. The PTFE nanoparticles on the surface of the waterproof fiber membrane are bonded by van der Waals forces, preventing chemical cross-linking agents from damaging the original porous structure of the fiber membrane and reducing damage to the hydrophobic structure. Simultaneously, the PTFE nanoparticles are mechanically embedded by the polyester fibers, improving peel strength.

[0095] Step S304, gradient curing and shaping.

[0096] Finally, the composite base fabric is dried in an oven at 80°C for 1 hour, then at 50°C for 2 hours, and then air-cooled at 20°C for 3 minutes (rapid cooling increases the crystallinity of tetrafluoroethylene and enhances its hydrophobicity).

[0097] Gradient curing and shaping eliminates differences in thermal expansion between layers, reduces internal stress, and avoids interlayer delamination.

[0098] The powder-spreading device uses a commercially available electrostatic ion powder spreader. The lamination equipment uses a commercially available flatbed hot press to ensure uniform pressure.

[0099] Step S4, molding creases.

[0100] The composite base fabric is folded in half at the folding point to be stored using a molding process. A pressure of 5-8 MPa is applied, and the electric heating film is heated to 110-120°C to replace steam and avoid the influence of humidity. The pressure holding time is 90-120 seconds to form creases and ensure that the creases penetrate into the fiber.

[0101] The molding equipment can employ the load crease device disclosed in Chinese Patent Publication No. CN113737358A.

[0102] This solution involves heating and molding the composite base fabric to create creases that conform to the folding trend of the umbrella surface when it is stored.

[0103] Example 1: A dual solvent of chlorobenzene as the first solvent and dimethyl sulfoxide as the second solvent (low-boiling point non-aqueous + high-boiling point hydrophilic).

[0104] The process parameters are as follows:

[0105] The volume ratio (v / v) of the first solvent to the second solvent is 9:1, 7:3, and 5:5 (v / v) for chlorobenzene and dimethyl sulfoxide, respectively.

[0106] Concentration of styrene-acrylonitrile copolymer: 350 mg / mL;

[0107] Ambient humidity 80%RH; voltage 12kV; flow rate 0.8mL / h;

[0108] The concentration of tetrabutylammonium perchlorate is 2.5 mg / mL;

[0109] Figure 2 This is a SEM image of the fiber cross-section from Example 1; as shown... Figure 2 As shown, Figure 2 The left figure shows that when the volume ratio of chlorobenzene / dimethyl sulfoxide is 9:1, there are tiny pores on the fiber surface that extend into the fiber interior. The diameter of the pores inside the fiber is larger than that of the pores on the fiber surface, but no pores appear in the fiber core. Figure 2 The central figure shows that when the volume ratio of chlorobenzene / dimethyl sulfoxide is 7:3, the pores extend from the fiber surface to the fiber core, and the pore diameter is relatively large, occupying most of the fiber space. Figure 2 The right-hand figure shows that when the volume ratio of chlorobenzene / dimethyl sulfoxide is 5:5, the fiber surface appears rough and granular, and the fiber interior exhibits a porous structure, but no obvious pores extending from the fiber surface to the fiber interior are observed.

[0110] Figure 3 This is a water contact angle profile diagram of Example 1; as shown Figure 3 As shown, Figure 3 The figure on the left shows that when the volume ratio of chlorobenzene to dimethyl sulfoxide is 9:1, the water contact angle is 134.88°. Figure 3 The central figure shows that when the volume ratio of chlorobenzene / dimethyl sulfoxide is 7:3, the water contact angle is 151.53°. Figure 3 The right-hand figure shows that when the volume ratio of chlorobenzene / dimethyl sulfoxide is 5:5, the water contact angle is 132.75°. It is evident that the waterproof fiber membranes of Example 1 all exhibit highly hydrophobic properties, especially when the volume ratio of chlorobenzene / dimethyl sulfoxide is 7:3, the water contact angle is 151.53°, demonstrating superhydrophobic properties.

[0111] Example 2: A dual solvent of chlorobenzene as the first solvent and N,N-dimethylformamide (DMF) as the second solvent.

[0112] The process parameters are as follows:

[0113] The volume ratio (v / v) of the first solvent to the second solvent: chlorobenzene / N,N-dimethylformamide are 9:1, 7:3, and 5:5 (v / v), respectively.

[0114] Concentration of styrene-acrylonitrile copolymer: 350 mg / mL;

[0115] Ambient humidity 80%RH; voltage 12kV; flow rate 0.8mL / h;

[0116] The concentration of tetrabutylammonium perchlorate is 2.5 mg / mL;

[0117] Figure 4 This is a SEM image of the fiber cross-section from Example 2; as shown. Figure 4 As shown, Figure 4 The left-hand figure shows that when the volume ratio of chlorobenzene to N,N-dimethylformamide is 9:1, there are tiny pores on the fiber surface, but these pores do not extend into the fiber interior. Figure 4 The central figure shows that when the volume ratio of chlorobenzene to N,N-dimethylformamide is 7:3, the pores extend from the fiber surface but do not extend to the fiber core. Figure 4 The right-hand figure shows that when the volume ratio of chlorobenzene to N,N-dimethylformamide is 5:5, the fiber surface is relatively smooth, but the fiber interior exhibits a porous structure. However, no obvious pores extending from the fiber surface to the fiber interior are observed. This is because when the proportion of hydrophilic solvent increases to a certain level, chlorobenzene evaporates first, causing water vapor in the air to condense. Due to the high proportion of hydrophilic solvent, water vapor can penetrate into the fiber jet. Water can be considered as a non-solvent of the polymer solute. When water evaporates with N,N-dimethylformamide (DMF), a porous morphology is formed inside the fiber.

[0118] The water contact angle of Example 2 is greater than 130°, which indicates that it has high hydrophobicity.

[0119] Example 3: A dual solvent of chlorobenzene as the first solvent and N,N-dimethylacetamide (DMAc) as the second solvent.

[0120] The process parameters are as follows:

[0121] The volume ratio (v / v) of the first solvent to the second solvent: chlorobenzene / N,N-dimethylacetamide are 9:1, 7:3, and 5:5 (v / v), respectively.

[0122] Concentration of styrene-acrylonitrile copolymer: 350 mg / mL;

[0123] Ambient humidity 80%RH; voltage 12kV; flow rate 0.8mL / h;

[0124] The concentration of tetrabutylammonium perchlorate is 2.5 mg / mL;

[0125] Figure 5 This is a SEM image of the fiber cross-section from Example 3; as shown. Figure 5 As shown, Example 3 and Example 2 have similar results. Figure 5 The left-hand figure shows that when the volume ratio of chlorobenzene to N,N-dimethylacetamide is 9:1, there are tiny pores on the fiber surface, but these pores do not extend into the fiber interior. Figure 5The central figure shows that when the volume ratio of chlorobenzene to N,N-dimethylacetamide is 7:3, the pores extend from the fiber surface but do not extend to the fiber core. Figure 5 The right-hand figure shows that when the volume ratio of chlorobenzene to N,N-dimethylacetamide is 5:5, the fiber surface is relatively smooth, but the fiber interior exhibits a porous structure. However, no obvious pores extending from the fiber surface to the fiber interior are observed. This is because when the proportion of hydrophilic solvent increases to a certain level, chlorobenzene evaporates first, causing water vapor in the air to condense. Due to the high proportion of hydrophilic solvent, water vapor can penetrate into the fiber jet. Water can be considered as a non-solvent of the polymer solute. When water and N,N-dimethylacetamide evaporate, a porous morphology is formed inside the fiber.

[0126] In Examples 1, 2, and 3, the first solvent was chlorobenzene, and the second solvent was dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide, respectively. When the hydrophilic second solvent constituted a low volume percentage (below 30%), surface pores were formed. When the hydrophilic second solvent accounted for a certain volume percentage (e.g., 50%), a porous structure was formed inside the fiber. The first solvent was always chlorobenzene, and the second solvent was dimethyl sulfoxide. A chlorobenzene / dimethyl sulfoxide volume ratio of 7:3 showed good performance in forming giant pores on the fiber surface.

[0127] Example 4: A dual solvent of chloroform as the first solvent and dimethyl sulfoxide as the second solvent.

[0128] Since dimethyl sulfoxide (DMSO) facilitates the formation of pores on the fiber surface, the second solvent is fixed as DMSO. In this embodiment, the first solvent is chloroform. The volume ratio (v / v) of the first solvent to the second solvent is 9:1 (v / v) for chloroform and DMSO.

[0129] Concentration of styrene-acrylonitrile copolymer: 350 mg / mL;

[0130] Ambient humidity 80%RH; voltage 12kV; flow rate 0.8mL / h;

[0131] The concentration of tetrabutylammonium perchlorate is 2.5 mg / mL.

[0132] Figure 6 This is a SEM image of the fiber cross-section in Example 4; the fiber is flat with nanoscale pores on its surface. Due to the low boiling point of chloroform and the high boiling point of dimethyl sulfoxide (189°C), chloroform evaporates rapidly during electrospinning, causing the fiber surface to solidify quickly. However, residual solvent remains inside the fiber. Therefore, when the fiber reaches the collecting plate, the outer polymer shell is too weak to maintain the cylindrical shape of the fiber, and the fiber collapses into a flat shape.

[0133] Example 5: A dual-solvent system consisting of a first solvent, methyl isobutyl ketone, and a second solvent, dimethyl sulfoxide.

[0134] Process parameters:

[0135] The volume ratio (v / v) of the first solvent to the second solvent is 9:1, 7:3, and 5:5 (v / v) for methyl isobutyl ketone and dimethyl sulfoxide, respectively.

[0136] Concentration of styrene-acrylonitrile copolymer: 350 mg / mL;

[0137] Ambient humidity 80%RH; voltage 12kV; flow rate 0.8mL / h;

[0138] The concentration of tetrabutylammonium perchlorate is 2.5 mg / mL.

[0139] Figure 7 This is a SEM image of the fiber cross-section from Example 5;

[0140] like Figure 7 As shown, Figure 7 The left figure shows that when the volume ratio of methyl isobutyl ketone / dimethyl sulfoxide is 9:1, there are small pores on the fiber surface. These pores extend slightly into the fiber interior, but the fiber collapses into a flat shape, which is the same as in Example 4. Figure 7 The central figure shows that when the volume ratio of methyl isobutyl ketone / dimethyl sulfoxide is 7:3, the pores extend from the fiber surface but do not extend to the fiber core. At the same time, small circular pores appear in the fiber core. Figure 7 The right-hand figure shows that when the volume ratio of methyl isobutyl ketone / dimethyl sulfoxide is 5:5, the fiber surface is relatively smooth, but the fiber interior exhibits a porous structure, although no obvious pores extending from the fiber surface to the fiber interior are observed.

[0141] Example 6: A dual solvent consisting of a first solvent, 1,1,2,2-tetrachloroethane (TeCA), and a second solvent, dimethyl sulfoxide.

[0142] Process parameters:

[0143] The volume ratio (v / v) of the first solvent to the second solvent is 9:1, 7:3, and 5:5 (v / v) for 1,1,2,2-tetrachloroethane and dimethyl sulfoxide, respectively.

[0144] Concentration of styrene-acrylonitrile copolymer: 350 mg / mL;

[0145] Ambient humidity 80%RH; voltage 12kV; flow rate 0.8mL / h;

[0146] The concentration of tetrabutylammonium perchlorate is 2.5 mg / mL.

[0147] Figure 8 This is a SEM image of the fiber cross-section from Example 6;

[0148] like Figure 8 As shown, Figure 8 The left-hand figure shows that when the volume ratio of 1,1,2,2-tetrachloroethane / dimethyl sulfoxide is 9:1, the fiber is spindle-shaped and has tiny pores on its surface. Figure 8 The central figure shows that when the volume ratio of 1,1,2,2-tetrachloroethane / dimethyl sulfoxide is 7:3, the pores extend from the fiber surface but do not extend to the fiber core. At the same time, small circular pores appear in the fiber core. Figure 8 The right-hand figure shows that when the volume ratio of 1,1,2,2-tetrachloroethane / dimethyl sulfoxide is 5:5, the fiber surface is relatively smooth, but the fiber interior exhibits a porous structure, although no obvious pores extending from the fiber surface to the fiber interior are observed.

[0149] Compare with Example 1, a dual solvent of chloroform and chlorobenzene.

[0150] The process parameters are the same as in Example 1 because both chloroform and chlorobenzene are good solvents for styrene-acrylonitrile copolymers and are immiscible with water. When using a dual solvent of chloroform and chlorobenzene, regardless of the ratio of the two solvents, it is impossible to stably electrospin fibers because both have low dielectric constants and low surface charges that prevent the formation of Taylor cones.

[0151] Compare with Example 2, a dual solvent of chloroform and ethanol.

[0152] Chloroform is a good solvent for styrene-acrylonitrile copolymers, while ethanol is a non-solvent for them. Ethanol has a boiling point of 78.4℃, slightly higher than chloroform (61.2℃). Due to this difference in boiling points, chloroform is more volatile than ethanol. When chloroform evaporates, the fiber surface temperature drops, and water vapor in the air condenses on the fiber surface. Water can be considered a non-solvent for polymers, and water and ethanol are well miscible. During electrospinning, droplets are dispersed on the fiber surface. When the solvent completely evaporates, surface pits are formed. Cross-sections show that these pits are only on the fiber surface, while the fiber center remains solid. However, its water contact angle is 118°, lower than 130°.

[0153] This method produces a waterproof fiber membrane using electrospinning with two solvents, both of which are good solvents for high-molecular-weight polymer solutes. Under specific parameters, fibers with surface pores and superhydrophobic properties can also be produced using a lower-boiling-point insoluble solvent and a higher-boiling-point soluble solvent.

[0154] It is worth noting that, since both solvents are good solvents, and exhibit a different pore morphology generation principle compared to traditional electrospinning methods:

[0155] Initially, since both are good solvents, the polymer is distributed in both solvents.

[0156] During jetting, water droplets condense on the jet surface. Since the minority of the secondary solution is hydrophilic, it tends to approach the jet surface and merge with the water droplets. At this point, the jet forms two phase regions: the main phase region and the surface phase region.

[0157] The main phase region, which is the main body of the jet, is mainly composed of the first solution and polymer.

[0158] The surface phase region is a granular region extending from the surface of the jet inwards. It is densely distributed on the surface of the jet and is mainly composed of the second solution and condensate.

[0159] First evaporation stage: In the main phase region, due to the lower boiling point of the first solution, it evaporates first, causing the main phase region to shrink. This shrinkage leads to an increase in the diameter of the surface phase region, which extends towards the core of the jet. The first solution in the main phase region continues to evaporate, leaving behind the polymer molecules to form the fibrous main structure.

[0160] Post-evaporation stage: After the second solution and condensate in the surface phase evaporate, pores are formed in the fibers.

[0161] Therefore, the binding ability of the hydrophilic second solvent with water has a crucial impact on the formation of pores on the fiber surface. In addition, the choice of a low-boiling-point, water-insoluble first solvent is also important for the formation of surface pores. If the boiling point of the first solvent is too low, it will lead to the formation of flat fibers, while the degree of hydrophobicity of the low-boiling-point solvent will also affect the formation of pore structures on the fiber surface.

[0162] Furthermore, due to the rapid evaporation rate, the initial evaporation stage and the subsequent evaporation stage are not entirely independent and sequential; these two stages partially overlap. In this case, the volume ratio of the first solvent to the second solvent affects the overlap between the two stages. When the volume ratio of the second solution is small, the initial evaporation stage dominates, the jet contracts overall, and the subsequent evaporation stage is mainly confined to the surface of the jet. Therefore, the resulting fibers mainly have tiny pores on the fiber surface. As the volume ratio of the second solution increases, the pores extend from the fiber surface to the fiber core. When the volume ratio of the first solution to the second solution is 1:1, pores are generated spontaneously inside the fiber, and these pores are not interconnected with the pores on the fiber surface.

[0163] An easy-folding umbrella is obtained by manufacturing an umbrella from the aforementioned composite base fabric.

[0164] This umbrella is woven with double-strand warp and weft threads, increasing the gap between the yarns to allow physical space for pre-creases. Regular creases are formed through heat pressing, allowing it to fold up neatly along these creases when closed. The rest of the umbrella surface exhibits excellent wrinkle resistance.

[0165] This umbrella has a contact angle of ≥150° (traditional coatings ≤120°), and its self-cleaning ability is close to that of a lotus leaf. It achieves long-lasting hydrophobicity through the micro-nano rough structure of the fiber membrane.

[0166] This umbrella uses EVA / PTFE partitioned bonding and gradient curing to strengthen the lamination interface and improve peel strength.

[0167] This umbrella uses readily available SAN raw materials and its process is compatible with existing equipment (pre-shrink machine, electrospinning machine, hot press). Through material innovation and process synergy, it achieves a balance between superhydrophobicity and easy folding, combining performance breakthroughs with mass production feasibility.

[0168] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any appropriate changes and variations made to the above embodiments within the essential spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for producing a superhydrophobic composite substrate, characterized in that, Includes the following steps: Step S1, preparation of the polyester surface layer; Step S2, preparation of the waterproof fiber membrane; the waterproof fiber membrane is prepared by electrospinning, and its raw materials include styrene-acrylonitrile copolymer and a two-component solvent; the two-component solvent is a good solvent for styrene-acrylonitrile copolymer; the two-component solvent consists of a low-boiling-point non-water-soluble first solvent and a high-boiling-point hydrophilic second solvent, and the volume ratio of the first solvent to the second solvent is (7-9):(1-3); the boiling point of the first solvent is below 133℃; the boiling point of the second solvent is above 146℃; Initially, since both solvents are good solvents, the styrene-acrylonitrile copolymer is distributed in both solvents; During jetting, water droplets condense on the jet surface. Since the minority second solvent is hydrophilic, it tends to approach the jet surface and merge with the water droplets. At this time, the jet forms two phase regions: the main phase region and the surface phase region. The main phase region, which is the main body of the jet, is mainly composed of the first solvent and styrene-acrylonitrile copolymer; The surface phase region is a granular region that extends from the surface of the jet inward. It is distributed with a high density on the surface of the jet and is mainly composed of the second solvent and condensate. First evaporation stage: In the main phase region, due to the lower boiling point of the first solvent, the first solvent evaporates first, and the main phase region shrinks. As a result, the diameter of the surface phase region increases and extends towards the core of the jet; the first solvent in the main phase region continues to evaporate, and the styrene-acrylonitrile copolymer is left behind to form the main fiber structure. Post-evaporation stage: After the second solvent and condensate in the surface phase evaporate, pores are formed in the fibers; Step S3, Lamination: The woven fabric is used as the inner layer, the waterproof fiber membrane is used as the middle layer, and the polyester surface layer is used as the outer layer. The layers are laminated and ironed to form a composite base fabric. Step S3 includes: Step S301, Inner layer pretreatment: First, sprinkle ethylene-vinyl acetate copolymer powder on the upper surface of the woven fabric at a rate of 12-15 g / m2; then preheat the inner layer at a temperature of 120-125℃ for 2-2.5 minutes to allow the ethylene-vinyl acetate copolymer powder to initially adhere to the woven fabric and prevent it from spilling during subsequent processing. Step S302, outer layer preprocessing; Then, polytetrafluoroethylene nanoparticles with an average particle size of 50nm are sprinkled on the waterproof fiber membrane at a rate of 12-15g / m2. The polyester surface layer is then covered on the surface of the waterproof fiber membrane and heated and dried at a temperature of 90-95℃ for 3-3.5 minutes. Step S303, three-layer composite lamination: Next, the dried waterproof fiber membrane bottom layer is covered on the upper surface of the woven fabric to form a composite base fabric, and then laminated and ironed. The ironing temperature is 130~135℃, the ironing time is 5~5.5min, and the pressure is 0.4~0.5MPa. Step S304, gradient curing and shaping: Finally, the composite base fabric is dried in an oven at 80°C for 1 hour, then at 50°C for 2 hours, and then air-cooled at 20°C for 3 minutes.

2. The method for producing a superhydrophobic composite substrate according to claim 1, characterized in that, Step S1 includes: Step S101, weaving: both warp and weft yarns are made of 30D / 48F polyester textured network yarn, which is woven on a loom to obtain polyester grey fabric; the polyester grey fabric has a basic unit of double warp and double weft; the arrangement pattern of the warp yarns is: synchronous two up and two down, that is, two adjacent warp yarns float synchronously on two weft yarns, and then the next two weft yarns sink synchronously. Step S102, Pre-shrinking: The polyester fabric is pre-shrinked using a pre-shrinking machine to remove residual tension, followed by rinsing and dewatering; Step S103, Water-repellent pretreatment: Impregnate the polyester fabric with a water-repellent finishing agent and dry it.

3. The method for producing a superhydrophobic composite substrate according to claim 2, characterized in that, Step S2 includes: Step S201, preparing the electrospinning solution: Styrene-acrylonitrile copolymer is used as the polymer solute and mixed with a two-element solvent. Then tetrabutylammonium perchlorate is added. The mixture is then heated and stirred until it is clear and transparent to obtain the electrospinning solution. The electrospinning solution is then allowed to stand and cool to room temperature. Step S202: Set the electrospinning experiment parameters; Step S203: Perform electrospinning, collect the electrospun fibers, and take out a waterproof fiber membrane with a thickness of 200μm.

4. The method for producing a superhydrophobic composite substrate according to claim 3, characterized in that, In step S201, the concentration of the styrene-acrylonitrile copolymer is 300~375 mg / mL; the concentration of tetrabutylammonium perchlorate is not greater than 2.5 mg / mL; the heating and stirring conditions are: heating temperature 65℃ and stirring for 12 hours; the first solvent is chloroform or chlorobenzene; the second solvent is dimethyl sulfoxide or N,N-dimethylformamide.

5. The method for producing a superhydrophobic composite substrate according to claim 3, characterized in that, In step S202, the feed flow rate is set to 1.5 mL / h; the voltage is set to 10.9 kV; the working distance is set to 19 cm; the temperature is controlled at 23-28℃; and the ambient relative humidity is controlled at 60%RH.

6. The method for producing a superhydrophobic composite substrate according to claim 3, characterized in that, It also includes step S4, molding crease: using molding process, the composite base fabric is folded at a specified position, a pressure of 5~8MPa is applied, and the electric heating film is heated to 110~120℃; the pressure holding time is 90~120 seconds to form a crease.

7. A foldable umbrella, characterized in that, Its umbrella surface is made of composite base fabric produced by the composite base fabric production method as described in any one of claims 1-6.

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