Multifunctional nanofiber membrane material for protective clothing and preparation method thereof

Abstract

The application belongs to the technical field of protective materials, and relates to preparation of a nanofiber membrane, and discloses a multifunctional nanofiber membrane material for protective clothing and a preparation method.The method comprises the following steps: preparing a skin-friendly base layer of TPU material; preparing a flame-retardant layer of PBI material; preparing a filter hydrophobic layer of PVDF material; preparing a reinforcing layer of PA6 material; and coating a protective outer layer of aramid material on the surface of the four-layer fiber membrane.The application adopts a needle-free electrostatic spinning process to spin layer by layer to obtain a multilayer composite nanofiber membrane of the skin-friendly base layer, the flame-retardant layer, the filter hydrophobic layer, the reinforcing layer and the protective outer layer, and solves the problems of needle blockage and low yield in the needle spinning of the traditional electrostatic spinning technology, and is more suitable for the mass production demand of current protective clothing and other protective equipment.

Description

Technical Field

[0001] This invention belongs to the field of protective materials technology, and relates to the preparation of nanofiber membranes, specifically a multifunctional nanofiber membrane material for protective clothing and its preparation method. Background Technology

[0002] Currently, the manufacturing processes for protective materials typically include lamination / hot pressing, spunbond-meltblown-spunbond composite processes, coating finishing processes, and knitted / woven multilayer fabric processes. These traditional processes generally use adhesives, which can easily lead to residue problems and delamination issues. Furthermore, it is difficult to balance the protective properties and breathability of the resulting nanofiber membranes, and the compatibility between different materials is poor, resulting in insufficient protective levels, poor filtration efficiency stability, and insufficient interlayer bonding strength, making delamination likely. The coating also suffers from poor uniformity and insufficient weather resistance, making it prone to cracking and peeling.

[0003] Taking electrospinning technology as an example, this method uses needle spinning, which has problems such as easy clogging of the needle and low output, and is not suitable for the current demand for mass production of protective clothing and other protective equipment; in addition, knitted fibers have problems such as coarse diameter, large pores, thick fabric, and low flexibility.

[0004] Therefore, there is an urgent need to invent a method for preparing a multifunctional nanofiber membrane for protective clothing, so as to prepare a multifunctional nanofiber membrane material that combines protection and breathability, in order to overcome the above problems. Summary of the Invention

[0005] To overcome the aforementioned deficiencies of the prior art, the present invention aims to provide a multifunctional nanofiber membrane material for protective clothing and its preparation method. This addresses the technical problems inherent in traditional electrospinning technology, which uses needle spinning, resulting in easy needle clogging and low production output; the coarse diameter, large pores, and heavy fabric of knitted fibers, leading to low flexibility; and the difficulty in balancing protection and breathability in traditional protective clothing materials, resulting in insufficient protection levels, poor filtration efficiency stability, insufficient interlayer bonding strength leading to delamination; and poor coating uniformity, insufficient weather resistance, and a tendency to crack and peel off.

[0006] This invention is achieved using the following technical solution:

[0007] In a first aspect, a multifunctional nanofiber membrane material for protective clothing includes: a skin-friendly base layer of TPU (polyurethane); a flame-retardant layer of PBI (polybenzimidazole); a hydrophobic filter layer of PVDF (polyvinylidene fluoride); a reinforcing layer of PA6 (polyamide 6); and a protective outer layer of aramid material covering the surface of the four-layer fiber membrane.

[0008] Secondly, a method for preparing a multifunctional nanofiber membrane for protective clothing includes the following steps:

[0009] S1. Preparation of skin-friendly base layer: TPU is dissolved in DMF solvent and added to a spinning device. The solution is sprayed to form a continuous jet, and the TPU fiber film is formed by volatilization and deposition.

[0010] S2. Preparation of flame retardant layer: PBI is dissolved in DMAc (dimethylacetamide) solvent and added to a spinning device to spin on the surface of TPU fiber film to form TPU / PBI composite film.

[0011] S3. Preparation of the hydrophobic filter layer: Prepare a mixed solvent of DMF and acetone, add PVDF powder to obtain a PVDF mixed solution; add to a spinning device for spinning, and deposit a TPU / PBI / PVDF composite film on the surface of TPU / PBI.

[0012] S4. Preparation of the reinforcing layer: Prepare a mixed solvent of formic acid and acetic acid, add PA6 to obtain a mixed solution; add to a spinning device to spin, form a PA6 jet, and after solvent evaporation and stretching and refining, form a film on the surface of TPU / PBI / PVDF, heat treat to obtain a four-layer composite film of TPU / PBI / PVDF / PA6.

[0013] S5. Coating the protective outer layer: Prepare a mixed solvent of DMAc and LiCl, add aramid to obtain a mixed solution, degas under vacuum, add to a spinning device for spinning, deposit on the surface of a four-layer TPU / PBI / PVDF / PA6 fiber membrane, and form the finished nanofiber membrane after hot pressing.

[0014] Furthermore, in step S1, the TPU solution has a mass fraction of 12%.

[0015] Furthermore, in step S1, the specific parameters of the spinning device are: voltage 15KV, receiving distance 15cm, solution propulsion rate 1ml / h, ambient temperature 25℃, and humidity 40%.

[0016] Furthermore, in step S3, the solvents DMF and acetone in the PVDF mixed solution are prepared at a mass ratio of 7:3, and the concentration of the solute PVDF is 15wt%.

[0017] Furthermore, in step S4, the solvent of the PA6 mixed solution is formic acid with a concentration of 88wt% and acetic acid prepared at a volume ratio of 9:1, and the concentration of solute PA6 is 10wt%.

[0018] Furthermore, in step S5, the vacuum degassing pressure is -0.1 MPa and the time is 30 min; the hot pressing pressure is 1.5 MPa and the time is 1 h.

[0019] Furthermore, in step S5, the solvents DMAc and LiCl in the aramid mixed solution are mixed in a ratio of 95:5 wt%, and the concentration of the solute aramid is 8 wt%.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] This invention utilizes a needleless electrospinning process to spin fibers layer by layer, creating a multi-layered composite nanofiber membrane consisting of a skin-friendly base layer, a flame-retardant layer, a hydrophobic filtration layer, a reinforcing layer, and a protective outer layer. This solves the problems of needle clogging and low yield associated with traditional electrospinning techniques that use needles, making it more suitable for the mass production needs of protective clothing and other protective equipment.

[0022] The multifunctional nanofiber membrane material prepared by this invention has the characteristics of flame retardancy, ultra-lightweight, high strength, high comfort and stable protective performance. It makes up for the defects of traditional protective clothing materials that are difficult to balance protection and breathability, improves the protection level and is of great significance for expanding the application scenarios of protective clothing. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram showing the structure of the multifunctional nanofiber membrane of the present invention.

[0025] In the diagram: 1-Skin-friendly base layer; 2-Flame-retardant layer; 3-Water-repellent filter layer; 4-Reinforcing layer; 5-Protective outer layer. Detailed Implementation

[0026] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0027] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0028] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0029] refer to Figure 1As shown, this invention prepares a five-layer multifunctional nanofiber membrane material by spinning the fibers layer by layer using a needleless electrospinning process. Specifically, it includes: a skin-friendly base layer of TPU8880 material; a flame-retardant layer of PBI material; a hydrophobic filtration layer of PVDF material; a reinforcing layer of PA6 material; and a protective outer layer of aramid 1313 (poly(m-phenylene isophthalamide) fiber) material coated on the surface of the four-layer fiber membrane.

[0030] The preparation method of the multifunctional nanofiber membrane of the present invention includes the following steps:

[0031] (1) Preparation of skin-friendly base layer

[0032] The skin-friendly base layer 1 is made of TPU8880 material, which has a microporous structure on its surface, allowing water vapor formed by sweat evaporation to diffuse into the external environment, keeping the skin dry; in addition, TPU8880 material is soft to the touch, comfortable, non-toxic and non-irritating, and has good biocompatibility.

[0033] TPU8880 was dissolved in DMF solvent and magnetically stirred at 60°C for 4 hours until completely dissolved, preparing a homogeneous solution with a mass fraction of 12%. After standing to remove bubbles, the solution was poured into a spinning device. The spinning device voltage was set to 15KV, the receiving distance to 15cm, the solution propulsion rate to 1ml / h, and the ambient temperature to 25°C and humidity to 40%. The device was started, and the TPU8880 solution formed a Taylor cone under the action of a high-voltage electric field and was ejected as a continuous jet. After the solvent evaporated, a TPU8880 nanofiber membrane was deposited on the receiving plate.

[0034] (2) Preparation of flame retardant layer

[0035] The flame retardant layer 2 is made of PBI material. PBI molecules contain a large number of aromatic rings and imidazole rings, and the limiting oxygen index is above 41°C, which is much higher than most polymers. It is difficult to burn in air without the need to add additional flame retardants. Moreover, there is no melting and dripping phenomenon when burning, but only slow carbonization. The amount of smoke and toxic gases released is very small, which meets the flame retardant requirements of high safety standards.

[0036] PBI was dissolved in DMAc solvent and stirred at 70°C for 5 hours to obtain a homogeneous solution. After standing for 12 hours, the solution was added to a spinning device and spun on the surface of a TPU fiber membrane at an ambient temperature of 20°C and a humidity of 30% to form a TPU8880 / PBI bilayer composite membrane.

[0037] (3) Preparation of a hydrophobic filter layer

[0038] The 3rd hydrophobic filter layer is made of PVDF material. PVDF has a long perfluoroalkyl chain structure, low surface energy, and naturally good hydrophobicity. The static contact angle can reach more than 90°. It also has high porosity, which can achieve efficient interception of microbial aerosols.

[0039] DMF and acetone were mixed in a 7:3 mass ratio as a solvent system. PVDF powder was added to the mixed solvent to prepare a 15wt% PVDF mixed solution. The solution was then magnetically stirred at 60℃ for 6 hours to form a uniform and transparent solution. The solution was then spun on the surface of TPU8880 / PBI using a spinning device with a spinning voltage of 20kV and a receiving distance of 15cm, depositing a TPU8880 / PBI / PVDF composite film.

[0040] Specifically, PVDF fiber membranes formed by electrospinning have high tensile strength and flexibility. The porous structure between fibers is not easily damaged by external forces and does not lose its hydrophobic effect. It can maintain stable physicochemical properties within the range of -40℃ to 150℃.

[0041] (4) Preparation of the reinforcing layer

[0042] The reinforcing layer 4 is made of polyamide 6. The amide bonds in the molecular chain of PA6 give the fiber good mechanical properties, high tensile strength and toughness, which can effectively improve the overall tear resistance and structural stability of the fiber membrane. At the same time, the PA6 film has a uniform porous structure, which can retain good air permeability.

[0043] Formic acid (88wt%) and acetic acid were mixed at a volume ratio of 9:1 to form a solvent system. PA6 was added to the mixed solvent to prepare a 10wt% PA6 mixed solution. The solution was then dissolved in a water bath at 50°C for 4 hours to form a homogeneous viscous solution. After centrifugation at 3000 rpm for 10 minutes, micro-bubbles were removed. The solution was then added to a spinning device, and a PA6 jet was formed under a high-voltage electric field. After solvent evaporation and stretching, a thin film was formed on the surface of TPU8880 / PBI / PVDF. The film was then heat-treated for 10 minutes to improve fiber crystallinity, resulting in a four-layer fiber membrane of TPU8880 / PBI / PVDF / PA6. Furthermore, the PA6 spinning solution exhibited good compatibility, preventing interlayer delamination.

[0044] (5) Covering the outer protective layer

[0045] The protective outer layer 5 is made of aramid 1313 material. The molecular structure of aramid 1313 contains a large number of aromatic rings and amide bonds, which endow the fiber with excellent high temperature resistance and flame retardancy. At the same time, aramid 1313 material has good chemical corrosion resistance and aging resistance, and as an outer layer, it can increase the environmental tolerance of the finished nanofiber membrane.

[0046] DMAc and LiCl were mixed in a 95:5 wt% ratio to prepare an 8 wt% aramid 1313 mixed solution. The solution was then magnetically stirred at 80℃ for 6 hours, followed by low-speed stirring in a 50℃ vacuum oven for 24 hours to obtain a viscous solution. The solution was then degassed under vacuum at -0.1 MPa for 30 minutes. The solution was then added to a spinning apparatus, with a spinning temperature of 25℃ and humidity of 40%, to deposit TPU8880 / PBI / PVDF / PA6 four-layer fiber membrane to form TPU8880 / PBI / PVDF / PA6 / 1313. Finally, the membrane was hot-pressed at 1.5 MPa for 1 hour to promote the diffusion and fusion of interlayer molecular chains, resulting in a five-layer TPU8880 / PBI / PVDF / PA6 / 1313 finished nanofiber membrane.

[0047] The method of this invention produces a multifunctional nanofiber membrane material for protective clothing, which features high-efficiency protection, breathability and comfort, flame retardancy and antistatic properties, as well as high toughness and durability. It can be used in the preparation of protective clothing for microparticles, bioaerosols, and liquid permeation.

[0048] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.

Claims

1. A multifunctional nanofiber membrane material for protective clothing, characterized in that: include: Skin-friendly TPU base layer; flame-retardant PBI layer; PVDF material for the hydrophobic filter layer; PA6 material for the reinforcing layer; And a protective outer layer of aramid material covering the surface of the four-layer fiber membrane.

2. A method for preparing a multifunctional nanofiber membrane for protective clothing, characterized in that: Includes the following steps: S1. Preparation of skin-friendly base layer: TPU is dissolved in DMF solvent and added to a spinning device. The solution is sprayed to form a continuous jet, and the TPU fiber film is formed by volatilization and deposition. S2. Preparation of flame retardant layer: PBI is dissolved in DMAc (dimethylacetamide) solvent and added to a spinning device to spin on the surface of TPU fiber film to form TPU / PBI composite film. S3. Preparation of the hydrophobic filter layer: Prepare a mixed solvent of DMF and acetone, add PVDF powder to obtain a PVDF mixed solution; add to a spinning device for spinning, and deposit a TPU / PBI / PVDF composite film on the surface of TPU / PBI. S4. Preparation of the reinforcing layer: Prepare a mixed solvent of formic acid and acetic acid, add PA6 to obtain a mixed solution; add to a spinning device to spin, form a PA6 jet, and after solvent evaporation and stretching and refining, form a film on the surface of TPU / PBI / PVDF, heat treat to obtain a four-layer composite film of TPU / PBI / PVDF / PA6. S5. Coating the protective outer layer: Prepare a mixed solvent of DMAc and LiCl, add aramid to obtain a mixed solution, degas under vacuum, add to a spinning device for spinning, deposit on the surface of a four-layer TPU / PBI / PVDF / PA6 fiber membrane, and form the finished nanofiber membrane after hot pressing.

3. The method for preparing the multifunctional nanofiber membrane for protective clothing according to claim 2, characterized in that: In step S1, the TPU solution has a mass fraction of 12%.

4. The method for preparing the multifunctional nanofiber membrane for protective clothing according to claim 3, characterized in that: In step S1, the specific parameters of the spinning device are: voltage 15KV, receiving distance 15cm, solution propulsion rate 1ml / h, ambient temperature 25℃, and humidity 40%.

5. The method for preparing the multifunctional nanofiber membrane for protective clothing according to claim 2, characterized in that: In step S3, the solvents DMF and acetone in the PVDF mixed solution are prepared at a mass ratio of 7:3, and the concentration of the solute PVDF is 15wt%.

6. The method for preparing the multifunctional nanofiber membrane for protective clothing according to claim 2, characterized in that: In step S4, the solvent of the PA6 mixed solution is formic acid with a concentration of 88wt% and acetic acid prepared at a volume ratio of 9:1, and the concentration of solute PA6 is 10wt%.

7. The method for preparing the multifunctional nanofiber membrane for protective clothing according to claim 2, characterized in that: In step S5, the vacuum degassing pressure is -0.1 MPa and the time is 30 min; the hot pressing pressure is 1.5 MPa and the time is 1 h.

8. The method for preparing the multifunctional nanofiber membrane for protective clothing according to claim 7, characterized in that: In step S5, the solvents DMAc and LiCl in the aramid mixed solution are mixed at a ratio of 95:5 wt%, and the concentration of the solute aramid is 8 wt%.

Images