Hydrophobic spandex as well as preparation method and fabric thereof

Abstract

The invention provides hydrophobic spandex and a preparation method and fabric thereof, the hydrophobic spandex is provided with an outer skin and an inner core, the outer skin component comprises hydrophobic modified polyurethane urea and a polymer except the polyurethane urea, the hydrophobic modified polyurethane urea is a continuous phase of the outer skin component, and the polymer is a dispersed phase of the outer skin component; the inner core component comprises polyurethane urea; and the mass of the outer skin accounts for 10-25% of the total mass of the hydrophobic spandex fiber. The hydrophobic spandex fabric is a waterproof fabric and is formed by blending hydrophobic spandex and other hydrophobic fibers, micromolecular siloxane is introduced into polyurethane urea of a spandex skin material in a chemical grafting mode, the hydrophobic performance of the spandex can be remarkably improved, and the hydrophobic effect is lasting.

Description

Technical Field

[0001] This invention relates to the field of polymer material preparation, specifically to a hydrophobic spandex and its preparation method, and a waterproof fabric containing the hydrophobic spandex. Background Technology

[0002] Spandex is a type of synthetic fiber, primarily composed of polyurethane. Spandex molecules contain numerous hydrophobic groups, such as methylene chains and aryl groups, making it a hydrophobic fiber suitable for the production of outdoor sportswear, swimwear, and other garments requiring high waterproofing. However, spandex itself has limited waterproofing properties, necessitating methods such as impregnation, coating, and lamination to enhance its waterproofing performance and make it more suitable for waterproofing materials. For example, patent CN103741473A creates a waterproof spandex fabric by coating two layers of liquid polypropylene and polytetrafluoroethylene onto the surface of the fabric; patent CN119932918A improves the waterproofing of spandex fabric by adding two different waterproofing agents: one containing polyurethane and the other containing paraffin and polyurethane. Existing technologies mainly achieve waterproofing by coating the surface of spandex fibers or spandex fabrics with waterproofing materials. However, this requires an additional post-processing step and more steps. Furthermore, during use, over time, especially with rubbing and machine washing, the added chemical waterproofing agents may fall off or weaken, thus reducing or even eliminating the waterproofing performance. Summary of the Invention

[0003] Technical problem: The purpose of this invention is to provide a hydrophobic spandex, its preparation method and its fabric, which has a good waterproof effect for a long time.

[0004] Technical solution: The present invention provides a hydrophobic spandex having an outer skin and an inner core. The outer skin component includes hydrophobically modified polyurethane urea and polymers other than polyurethane urea. The hydrophobically modified polyurethane urea is the continuous phase of the outer skin component, and the polymer is the dispersed phase of the outer skin component. The inner core component includes polyurethane urea.

[0005] The polymer has a melting temperature of 170°C or higher, preferably 200-280°C; and is insoluble in N,N-dimethylacetamide (DMAc) and / or N,N-dimethylformamide (DMF) below 50°C, preferably insoluble in N,N-dimethylacetamide (DMAc) and / or N,N-dimethylformamide (DMF) below 100°C.

[0006] The polymer includes polyester, which is at least one of polycarbonate, polylactic acid, and polyphthalate; the polyphthalate includes at least one of polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate; the polymer content is 5-30% by mass, calculated based on the skin mass; the polymer is in solid particulate form with a particle size of 5-10 μm.

[0007] The raw materials for preparing the hydrophobically modified polyurethane urea of ​​the outer skin component include polymeric polyols, polyisocyanates, chain extenders, end-capping agents, and hydroxysiloxanes; the raw materials for preparing the polyurethane of the inner core component include polymeric polyols, polyisocyanates, chain extenders, and end-capping agents. The polymer polyol is preferably a polyether polyol, including any one or a combination of at least two of polytetramethylene ether diol, polyethylene glycol, or polypropylene glycol, and more preferably polytetramethylene ether diol; the number average molecular weight of the polyether polyol is 1000-4000 g / mol; further, the number average molecular weight of the polyether polyol in the outer skin component is 3000-4000 g / mol, and the number average molecular weight of the polyether polyol in the inner core component is 1000-3000 g / mol.

[0008] The end-capping agent comprises a monoamine having 2 to 20 carbon atoms, more preferably any one or a combination of at least two of diethylamine, isopropylamine, n-butylamine, tert-butylamine, hexylamine diethylamine, dimethylamine, di-n-butylamine, di-tert-butylamine, diisobutylamine, diisopropylamine, diethylamine, dipropylamine, cyclohexylamine, or ethanolamine; the chain extender comprises a diamine having 2 to 30 carbon atoms, more preferably any one or a combination of at least two of ethylenediamine, propylenediamine, butyldiamine, pentanediamine, methylpentanediamine, methylpropylenediamine, hexanediamine, phenylenediamine, phenylenediamine, diaminocyclohexane, hexamethylenediamine, or 3,3'-dimethyl-4,4-diaminodicyclohexylmethane.

[0009] The hydroxysiloxanes mentioned include one or more of hexadecyl-1,15-dihydroxyoctasiloxane, 1,3-di(4-hydroxybutyl)-1,1,3,3-tetramethyldisiloxane, and 1,3-di(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane.

[0010] The polyisocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate or dicyclohexylmethane diisocyanate, and is more preferably diphenylmethane diisocyanate.

[0011] The outer sheath accounts for 10%-25% of the total mass of the hydrophobic spandex fiber.

[0012] The method for preparing hydrophobic spandex of the present invention comprises: The method for preparing the spinning solution for the outer skin includes: A method for preparing hydrophobically modified polyurethane urea includes: reacting a polymeric polyol, a hydroxysiloxane, and a polyisocyanate to obtain an isocyanate-terminated prepolymer; dissolving the prepolymer in a solvent; adding a chain extender and a capping agent to continue the reaction to obtain a hydrophobically modified polyurethane urea solution; wherein the isocyanate group content of the isocyanate-terminated prepolymer is 1.5-2.2% by mass; the hydroxysiloxane content is 5-15% by mass, calculated based on the mass of the polymeric polyol and the hydroxysiloxane; the molar ratio of the chain extender to the capping agent is 6:1-10:1; the molar ratio of the amine group to the NCO group of the prepolymer in the chain extender and the capping agent is 1.02:1-1.1:1; the solvent includes N,N-dimethylacetamide (DMAc) and / or N,N-dimethylformamide (DMF); The polymer is added to a hydrophobically modified polyurethane urea solution and mixed evenly to obtain the outer sheath spinning solution; the preparation method of the inner core spinning solution includes: A prepolymer with isocyanate-terminated structure is obtained by reacting a polymeric polyol and a polyisocyanate. The prepolymer is dissolved in a solvent, and a chain extender and a capping agent are added to continue the reaction to obtain a spinning solution containing polyurethane urea for the inner core. The isocyanate group mass content of the isocyanate-terminated prepolymer is 2.4-3.0%; the molar ratio of the chain extender to the capping agent is 6:1-10:1; the molar ratio of the amine groups to the NCO groups in the chain extender and the capping agent is 1.02:1-1.1:1; the solvent includes N,N-dimethylacetamide (DMAc) and / or N,N-dimethylformamide (DMF); the method for preparing the hydrophobic spandex includes: The outer sheath spinning solution and the inner core spinning solution are respectively fed into a spinneret sheath-core assembly with two flow paths, one for the sheath layer and one for the core layer, for spinning. Finally, they are gathered together and extruded into filaments to obtain the hydrophobic spandex with the sheath-core structure. The spinning is dry spinning. Preferably, the spinning temperature is 240-260℃ for the upper channel, 210-220℃ for the middle channel, and 170-190℃ for the lower channel.

[0013] Waterproof fabrics using the hydrophobic spandex of the present invention include fabrics made by blending hydrophobic spandex with other hydrophobic fibers, wherein the other hydrophobic fibers include one of modified polyester and / or nylon.

[0014] Beneficial effects: Introducing small-molecule siloxanes into polyurethane urea in spandex outer materials via chemical grafting can significantly improve the hydrophobic properties of spandex, resulting in a long-lasting hydrophobic effect. High-melting-temperature polymer particles that are not easily soluble in organic solvents can be uniformly dispersed in the spinning solution without dissolving. After spinning, they can be dispersed as a dispersed phase in the outer material, improving the roughness of spandex without affecting its weaving process. Furthermore, after spandex is woven into fabric, it generally requires an alkali treatment process. During alkali treatment, some polyester is hydrolyzed by the alkali solution, forming a certain rough surface on the spandex, further increasing the surface roughness of the spandex fibers and thus enhancing its water resistance. Detailed Implementation

[0015] The present invention will be further described below with reference to specific embodiments, providing a detailed explanation of the preparation method of spandex and the spandex itself. The advantages and features of the present invention will become clearer as the description unfolds. However, the embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention.

[0016] A hydrophobic spandex includes a cross-section having an outer skin and an inner core. The outer skin component includes hydrophobically modified polyurethane urea and polymers other than polyurethane urea. The hydrophobically modified polyurethane urea is the continuous phase of the outer skin component, and the other polymers are the dispersed phase of the outer skin component. The core component includes polyurethane urea; The hydrophobic spandex is obtained by dry spinning; The polymer has a melting temperature above 170°C and is insoluble in N,N-dimethylacetamide (DMAc) and / or N,N-dimethylformamide (DMF) below 50°C. Preferably, the melting temperature is 200-280℃; As an example, the melting temperature is 220-280°C; Preferably, the substance is insoluble in N,N-dimethylacetamide (DMAc) and / or N,N-dimethylformamide (DMF) below 100°C. The polymer includes polyester, and the polyester includes at least one of polycarbonate, polylactic acid, and polyphthalate; Preferably, the polyester comprises polyphthalate, and the polyphthalate comprises at least one of polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate. In this invention, the polymer is dispersed as a dispersed phase in a hydrophobically modified polyurethane urea, which is a continuous phase, and the polymer is dispersed on the surface and inside of the outer skin.

[0017] The polymer content is 5-30% by mass, calculated based on the skin mass; The outer sheath accounts for 10%-25% of the total mass of the hydrophobic spandex fiber, preferably 15%-20%.

[0018] In this invention, a lower percentage of the outer sheath mass can avoid the influence of the hydrophobic sheath on the physical properties of the spandex fiber. The raw materials for preparing the hydrophobically modified polyurethane urea include polymeric polyols, polyisocyanates, chain extenders, end-capping agents, and hydroxysiloxanes. The raw materials for preparing the polyurethane urea include polymeric polyols, polyisocyanates, chain extenders, and end-capping agents; The polymer polyols include polyether polyols, including any one or a combination of at least two of polytetramethylene ether diol, polyethylene glycol or polypropylene glycol, more preferably polytetramethylene ether diol; the number average molecular weight of the polyether polyols is 1000-4000 g / mol. Furthermore, the number average molecular weight of the polyether polyol in the skin layer is 3000-4000 g / mol, and the number average molecular weight of the polyether polyol in the core layer is 1000-3000 g / mol. In this invention, the polyether polyol of the skin layer with a molecular weight of 3000-4000 g / mol can improve the tensile properties of the spandex. The polyisocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate or dicyclohexylmethane diisocyanate, and is more preferably diphenylmethane diisocyanate. The chain extender includes diamines having 2 to 30 carbon atoms, and further includes any one or a combination of at least two of the following: ethylenediamine, propylenediamine, butanediamine, pentanediamine, methylpentanediamine, methylpropylenediamine, hexanediamine, phenylenediamine, phenylenediamine, diaminocyclohexane, hexamethylenediamine, or 3,3'-dimethyl-4,4-diaminodicyclohexylmethane; The capping agent comprises a monoamine having 2 to 20 carbon atoms, and is more preferably any one or a combination of at least two of the following: diethylamine, isopropylamine, n-butylamine, tert-butylamine, hexylamine diethylamine, dimethylamine, di-n-butylamine, di-tert-butylamine, diisobutylamine, diisopropylamine, diethylamine, dipropylamine, cyclohexylamine, or ethanolamine. The hydroxysiloxanes mentioned include one or more of hexadecyl-1,15-dihydroxyoctasiloxane, 1,3-bis(4-hydroxybutyl)-1,1,3,3-tetramethyldisiloxane, and 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane. In this invention, small molecule siloxanes are introduced into the molecular structure of polyurethane urea through chemical polymerization to obtain hydrophobically modified polyurethane urea. The small molecule siloxanes are uniformly distributed in the molecular chain. Siloxanes have better hydrophobic effects than aliphatic hydrocarbon hydrophobic agents, and the chemical grafting method has long-lasting hydrophobic properties. The method for preparing the outer sheath spinning solution includes: (1) The preparation method of hydrophobic modified polyurethane urea includes: reacting polymer polyol, hydroxysiloxane and polyisocyanate to obtain isocyanate-terminated prepolymer, dissolving the prepolymer in a solvent, adding chain extender and end-capping agent to continue the reaction to obtain hydrophobic modified polyurethane urea solution. (2) Add the polymer to the hydrophobically modified polyurethane urea solution and mix evenly to obtain the outer skin spinning solution; In step (1), the isocyanate-terminated prepolymer has an isocyanate group content of 1.5-2.2%, which can improve the tensile properties of spandex within this isocyanate group content range. The mass percentage of hydroxysiloxane in step (1) is 5-15%, calculated based on the mass of the polymer polyol and hydroxysiloxane; In step (1), the molar ratio of chain extender to end capping agent is 6:1-10:1; In step (1), the molar ratio of amine groups to NCO groups in the chain extender and end-capping agent is 1.02:1-1.1:1; The polymer in step (2) is in the form of solid particles with a particle size of 5-10 μm. In this invention, the polymer particle size refers to a D90 of 5-10 μm.

[0019] The solvents include N,N-dimethylacetamide (DMAc) and / or N,N-dimethylformamide (DMF). The method for preparing the inner core spinning solution includes: reacting a polymeric polyol and a polyisocyanate to obtain an isocyanate-terminated prepolymer, dissolving the prepolymer in a solvent, adding a chain extender and a terminator to continue the reaction to obtain an inner core spinning solution containing polyurethane urea. The isocyanate-terminated prepolymer has an isocyanate group content of 2.4-3.0% by mass. In step (1), the molar ratio of chain extender to end capping agent is 6:1-10:1; In step (1), the molar ratio of amine groups to NCO groups in the chain extender and end-capping agent is 1.02:1-1.1:1; The solvents include N,N-dimethylacetamide (DMAc) and / or N,N-dimethylformamide (DMF); Catalysts can be used to accelerate the reaction during the polymerization step of polyurethane urea.

[0020] The method for preparing hydrophobic spandex includes: passing the outer sheath spinning solution and the inner core spinning solution into a spinneret sheath-core assembly with two flow paths, sheath and core, respectively, for spinning, and finally converging them together and extruding them into filaments to obtain the hydrophobic spandex with the sheath-core structure. The spinning process is dry spinning. The dry spinning process includes the steps of spraying, stretching, and drying. Furthermore, the spinning temperature is 240-260℃ for the upper tunnel, 210-220℃ for the middle tunnel, and 170-190℃ for the lower tunnel. In this invention, the polymer is insoluble in solvents at low temperatures and exists as solid particles in the outer spinning solution. During dry spinning, although the temperature of the spinning tunnel is relatively high, the spandex has a short residence time, generally less than 1 second, and the evaporation of the solvent also carries away a large amount of heat. The fiber surface temperature is not high during the fiber formation process in the tunnel. The high melting point of the polymer prevents it from easily melting during spinning. Therefore, the polymer can always be dispersed as a dispersed phase inside and on the surface of the hydrophobic spandex outer sheath. The particle size of 5-10 μm can slightly increase the roughness of the spandex without affecting its weaving and processing. In addition, after spandex is woven into fabric, it generally needs to undergo an alkali treatment process. As the preferred dispersed phase, the polyester dispersed on the outer surface is hydrolyzed to a certain extent by the alkali solution, forming a certain rough surface on the spandex surface, further increasing the surface roughness of the spandex fiber, thereby increasing its water resistance.

[0021] If the polymer particle size is too small, it will not be able to form an effective roughness on the surface after being dissolved in alkali. However, it cannot be too large, exceeding the thickness of the sheath. If the particle size is too large, it will also cause clogging of the filter screen of the spinning component, affecting production. The amount of polymer added should ensure that it has a certain density distribution in the sheath, while minimizing its impact on the physical properties of the entire spandex fiber.

[0022] In some embodiments of the present invention, the outer sheath spinning solution and the inner core spinning solution are subjected to a curing treatment before spinning. The curing temperature is 30~50℃, and the curing time is not specifically required, as long as each raw material is fully cured. Furthermore, functional auxiliaries commonly used in the field of spandex may be optionally added to the outer sheath spinning solution and / or the inner core spinning solution, including one or more of antioxidants, UV stabilizers, anti-yellowing agents, matting agents, dyeing auxiliaries, and chlorine-resistant auxiliaries. In this invention, there is no particular limitation on the amount of functional additives added, as long as they do not degrade the performance of the spandex.

[0023] A waterproof fabric comprising the aforementioned hydrophobic spandex.

[0024] Waterproof fabrics include fabrics woven from a blend of hydrophobic spandex and other hydrophobic fibers, wherein the other hydrophobic fibers include one of modified polyester and / or nylon.

[0025] The following embodiments are used to describe the production process of the present invention in detail, but these embodiments should not be construed as limiting the present invention in any way.

[0026] Example 1: (1) Outer skin material: Hydrophobically modified polyurethane urea: the polyether polyol is polytetramethylene ether diol with a molecular weight of 3000 g / mol, the hydroxysiloxane is hexadecyl-1,15-dihydroxyoctasiloxane, the polyisocyanate is diphenylmethane diisocyanate, the diamine is ethylenediamine, the monoamine is diethylamine, and the hydroxysiloxane accounts for 12% of the total mass of the hydroxysiloxane and the polyether polyol; Polymer: Polyethylene terephthalate (PET) with a melt temperature of approximately 250°C, a D90 particle size of 6 μm, and a polymer content of 15% by mass, calculated based on the mass of the spandex sheath.

[0027] (2) Inner core material: Polyurethane urea: The polyether polyol is polytetramethylene ether diol with a molecular weight of 1800 g / mol, the polyisocyanate is diphenylmethane diisocyanate, the diamine is ethylenediamine, and the monoamine is diethylamine.

[0028] (3) Spandex fiber: The outer sheath material accounts for 18% of the total mass of spandex fiber.

[0029] Example 2: The difference from Example 1 is that in the outer skin raw material, the hydroxysiloxane is 1,3-bis(4-hydroxybutyl)-1,1,3,3-tetramethyldisiloxane, the hydroxysiloxane accounts for 8% of the total mass of hydroxysiloxane and polyether polyol, the polymer D90 particle size is 8 μm, the polymer mass content is 5%, and other aspects remain the same.

[0030] Example 3: The difference from Example 1 is that in the outer skin raw material, hydroxysiloxane accounts for 8% of the total mass of hydroxysiloxane and polyether polyol, the polymer is polybutylene terephthalate (PBT) with a melting temperature of about 230°C, the polymer D90 particle size is 8μm, the polymer mass content is 25%, and other aspects remain the same.

[0031] Example 4: The difference from Example 1 is that the polymer D90 in the outer skin material has a particle size of 3 μm, while the others remain the same.

[0032] Example 5: The difference from Example 1 is that the polymer D90 in the outer skin material has a particle size of 15 μm, while the others remain the same.

[0033] Example 6: The difference from Example 1 is that the hydroxysiloxane in the outer skin material is a 1550 g / mol molecular weight hydroxypolysiloxane (brand name Silok from Guangzhou Silok New Material Co., Ltd.). ® (8812F2 product), everything else remains the same.

[0034] Example 7: The difference from Example 1 is that the outer sheath material accounts for 40% of the total mass of the spandex fiber, while the rest remains the same.

[0035] Example 8: The difference from Example 1 is that the polyether polyol in the outer skin material is polytetramethylene ether diol with a molecular weight of 1800 g / mol, while the others remain the same.

[0036] Example 9: The difference from Example 1 is that the polymer in the outer skin material is polycarbonate with a melting temperature of about 215°C, while the others remain the same.

[0037] Example 10: The difference from Example 1 is that the polymer in the outer skin material is polylactic acid with a melting temperature of about 180°C, while the others remain the same.

[0038] Example 11: The difference from Example 1 is that the polymer in the outer skin material is polytetrafluoroethylene with a melting temperature of about 330°C, while the others remain the same.

[0039] Comparative Example 1: The difference from Example 1 is that no polymer is added to the outer skin material, while everything else remains the same.

[0040] Comparative Example 2: The difference from Example 1 is that hydroxysiloxane is not added to the outer skin material; instead, an equal mass of polytetramethylene ether diol is used as a substitute, while other aspects remain the same.

[0041] Comparative Example 3: The difference from Example 1 is that no polymer is added to the outer skin material; instead, calcium carbonate particles of equal mass are used to replace the polymer, while everything else remains the same.

[0042] The raw materials of Examples 1-11 and Comparative Examples 1-3 were used to prepare outer sheath spinning solutions and inner core spinning solutions respectively according to the following preparation methods, and then spun to obtain spandex 1-11 and comparative spandex 1-3: (1) Preparation of outer spinning solution: Polyether polyol, polyisocyanate and / or hydroxysiloxane were added to a reactor and reacted at 85°C for 2 hours to obtain an isocyanate-terminated polyurethane prepolymer with an NCO content of 2%. Polyurethane prepolymer is dissolved in DMAc and reacted with a mixed amine solution containing chain extender and end-capping agent. The reaction temperature is controlled at 60-80℃, the mass concentration of the amine solution is 7%, the molar ratio of diamine to monoamine in the mixed amine is controlled at 8:1, and the molar ratio of amine groups to NCO groups in the prepolymer in the diamine and monoamine is 1.02:1. The reaction yields a stock solution of hydrophobically modified polyurethane urea with a mass concentration of 35%. Based on the above examples and comparative raw materials, polymer particles were selectively added to the outer sheath spinning solution, and the solution was aged at 40°C for 35 hours to obtain the outer sheath spinning solution.

[0043] (2) Preparation of inner core spinning solution: Polyether polyol and polyisocyanate were added to the reactor and reacted at 85°C for 2 hours to obtain isocyanate-terminated polyurethane prepolymer. The NCO content of the prepolymer was 2.5% by mass. Polyurethane prepolymer is dissolved in DMAc and reacted with a mixed amine solution containing chain extender and end capping agent. The reaction temperature is controlled at 60-80℃, the mass concentration of the amine solution is 7%, the molar ratio of diamine to monoamine in the mixed amine is controlled at 8:1, and the molar ratio of amine groups to NCO groups in the prepolymer is 1.03:1. The reaction yields a core spinning solution with a mass concentration of 35%. The inner core spinning solution was aged at 40°C for 35 hours to obtain the inner core spinning solution.

[0044] (2) Preparation of spandex: The outer sheath spinning solution and the inner core spinning solution are respectively fed into a spinneret sheath-core assembly with two flow paths for sheath and core layers for dry spinning, spraying, stretching and drying steps, and extrusion into filaments to obtain the hydrophobic spandex with sheath-core structure, and the denier of the spandex is 44 dtex. The spinning temperatures are as follows: 240℃ for the upper tunnel, 210℃ for the middle tunnel, and 175℃ for the lower tunnel.

[0045] Performance testing of spandex fibers: (1) Mechanical properties: The spandex fiber was tested using a constant speed tensile strength tester. The elongation at break was tested under the specified length and pretension of the sample.

[0046] (2) Test of hydrophobicity of spandex fiber: The spandex fiber was woven into pure spandex socks using a special spandex knitting machine (Yicheng International Industry (Hong Kong) Co., Ltd., model AFK-S). After alkali treatment, rinsing with water and drying, the water repellency level was determined by GB / T4745-2012 "Test and evaluation of waterproof performance of textiles - water repellency method". The water repellency level is divided into 0-5 levels, and the higher the level, the better the waterproof performance.

[0047] (3) Fiber spinnability test: The number of faults that occur on a spandex spinning production line in a day is less than 5, indicating good spinnability, and 5-10 indicates average spinnability.

[0048] The properties of the spandex fibers prepared in the examples and comparative examples are as follows:

Claims

1. A hydrophobic spandex, characterized in that, The hydrophobic spandex has an outer skin and an inner core. The outer skin component includes hydrophobically modified polyurethane urea and polymers other than polyurethane urea. The hydrophobically modified polyurethane urea is the continuous phase of the outer skin component, and the polymers are the dispersed phase of the outer skin component. The inner core component includes polyurethane urea.

2. The hydrophobic spandex according to claim 1, characterized in that, The polymer has a melting temperature of 170°C or higher, preferably 200-280°C; and is insoluble in N,N-dimethylacetamide (DMAc) and / or N,N-dimethylformamide (DMF) below 50°C, preferably insoluble in N,N-dimethylacetamide (DMAc) and / or N,N-dimethylformamide (DMF) below 100°C.

3. The hydrophobic spandex according to claim 1, characterized in that, The polymer includes polyester, which is at least one of polycarbonate, polylactic acid, and polyphthalate; the polyphthalate includes at least one of polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate; the polymer content is 5-30% by mass, calculated based on the skin mass; the polymer is in solid particulate form with a particle size of 5-10 μm.

4. The hydrophobic spandex according to claim 3, characterized in that, The raw materials for preparing the hydrophobically modified polyurethane urea of ​​the outer skin component include polymeric polyols, polyisocyanates, chain extenders, end-capping agents, and hydroxysiloxanes; the raw materials for preparing the polyurethane of the inner core component include polymeric polyols, polyisocyanates, chain extenders, and end-capping agents. The polymer polyol is preferably a polyether polyol, including any one or a combination of at least two of polytetramethylene ether diol, polyethylene glycol, or polypropylene glycol, and more preferably polytetramethylene ether diol; the number average molecular weight of the polyether polyol is 1000-4000 g / mol; further, the number average molecular weight of the polyether polyol in the outer skin component is 3000-4000 g / mol, and the number average molecular weight of the polyether polyol in the inner core component is 1000-3000 g / mol.

5. The hydrophobic spandex according to claim 4, characterized in that, The end-capping agent comprises a monoamine having 2 to 20 carbon atoms, more preferably any one or a combination of at least two of diethylamine, isopropylamine, n-butylamine, tert-butylamine, hexylamine diethylamine, dimethylamine, di-n-butylamine, di-tert-butylamine, diisobutylamine, diisopropylamine, diethylamine, dipropylamine, cyclohexylamine, or ethanolamine; the chain extender comprises a diamine having 2 to 30 carbon atoms, more preferably any one or a combination of at least two of ethylenediamine, propylenediamine, butyldiamine, pentanediamine, methylpentanediamine, methylpropylenediamine, hexanediamine, phenylenediamine, phenylenediamine, diaminocyclohexane, hexamethylenediamine, or 3,3'-dimethyl-4,4-diaminodicyclohexylmethane.

6. The hydrophobic spandex according to claim 5, characterized in that, The hydroxysiloxanes mentioned include one or more of hexadecyl-1,15-dihydroxyoctasiloxane, 1,3-di(4-hydroxybutyl)-1,1,3,3-tetramethyldisiloxane, and 1,3-di(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane.

7. The hydrophobic spandex according to claim 6, characterized in that, The polyisocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate or dicyclohexylmethane diisocyanate, and is more preferably diphenylmethane diisocyanate.

8. The hydrophobic spandex according to claim 7, characterized in that, The outer sheath accounts for 10%-25% of the total mass of the hydrophobic spandex fiber.

9. A method for preparing hydrophobic spandex as described in any one of claims 1-8, characterized in that, The method for preparing the spinning solution for the outer skin includes: A method for preparing hydrophobically modified polyurethane urea includes: reacting a polymeric polyol, a hydroxysiloxane, and a polyisocyanate to obtain an isocyanate-terminated prepolymer; dissolving the prepolymer in a solvent; adding a chain extender and a capping agent to continue the reaction to obtain a hydrophobically modified polyurethane urea solution; wherein the isocyanate group content of the isocyanate-terminated prepolymer is 1.5-2.2% by mass; the hydroxysiloxane content is 5-15% by mass, calculated based on the mass of the polymeric polyol and the hydroxysiloxane; the molar ratio of the chain extender to the capping agent is 6:1-10:1; the molar ratio of the amine group to the NCO group of the prepolymer in the chain extender and the capping agent is 1.02:1-1.1:1; the solvent includes N,N-dimethylacetamide (DMAc) and / or N,N-dimethylformamide (DMF); The polymer was added to the hydrophobically modified polyurethane urea solution and mixed evenly to obtain the outer skin spinning solution; The methods for preparing the spinning solution for the inner core include: A prepolymer with isocyanate-terminated structure is obtained by reacting a polymeric polyol and a polyisocyanate. The prepolymer is dissolved in a solvent, and a chain extender and a capping agent are added to continue the reaction to obtain a spinning solution containing polyurethane urea for the inner core. The isocyanate group mass content of the isocyanate-terminated prepolymer is 2.4-3.0%; the molar ratio of the chain extender to the capping agent is 6:1-10:1; the molar ratio of the amine groups to the NCO groups in the chain extender and the capping agent is 1.02:1-1.1:1; the solvent includes N,N-dimethylacetamide (DMAc) and / or N,N-dimethylformamide (DMF). The method for preparing hydrophobic spandex includes: The outer sheath spinning solution and the inner core spinning solution are respectively fed into a spinneret sheath-core assembly with two flow paths, one for the sheath layer and one for the core layer, for spinning. Finally, they are gathered together and extruded into filaments to obtain the hydrophobic spandex with the sheath-core structure. The spinning is dry spinning. Preferably, the spinning temperature is 240-260℃ for the upper channel, 210-220℃ for the middle channel, and 170-190℃ for the lower channel.

10. The waterproof fabric according to any one of claims 1-8, characterized in that, The waterproof fabric comprises a fabric made of a blend of hydrophobic spandex and other hydrophobic fibers, wherein the other hydrophobic fibers include one of modified polyester and / or nylon.

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