Melted electrostatic spinning polymer / molecular sieve blended composite fiber as well as preparation method and application thereof

Abstract

The invention discloses a fused electrostatic spinning polymer / molecular sieve blended composite fiber as well as a preparation method and application thereof. The melt electrostatic spinning polymer / molecular sieve blended composite fiber is prepared from the following raw materials in parts by weight: 25-90 parts of a thermoplastic polymer matrix, 5-75 parts of a molecular sieve, 1-10 parts of a compatibilizer and 0-5 parts of a conductive additive. According to the polymer / molecular sieve blended composite fiber material and the preparation technology, no solvent participates in the whole process, and the green manufacturing requirement is met. Moreover, in the fiber material, the molecular sieves can be uniformly distributed on the superfine polymer fibers, scanning electron microscope pictures show that the molecular sieves are uniformly embedded into the material, no aggregate larger than 10 microns exists, and the fiber material has a hierarchical pore structure, a high specific surface area and excellent mechanical properties. Therefore, the fiber material can be applied to the fields of air filtration, catalytic reaction, drying purification, adsorption separation and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of the intersection of functional fiber materials and polymer composite materials, and specifically relates to a melt electrospun polymer / molecular sieve blended composite fiber and a preparation method and application thereof. Background Art

[0002] Molecular sieve is a synthetic hydrated aluminosilicate (zeolite) or natural zeolite with the function of screening molecules. Its structure has many pores with uniform pore size and neatly arranged holes. Molecular sieves of different pore sizes separate molecules of different sizes and shapes. It has high adsorption capacity, strong selectivity and high temperature resistance. It is widely used in organic chemical industry and petrochemical industry. It is also an excellent adsorbent for coal gas dehydration. It is also increasingly valued in waste gas purification. Existing molecular sieves are mostly used in the form of dispersed blocks and microspheres or dense membranes (non-porous) materials with a size of more than millimeters. The internal pores are easily embedded by the polymer matrix, resulting in insufficient exposure of adsorption and catalytic sites. In order to achieve better application of molecular sieves in air filtration, catalytic reaction, drying and static, adsorption separation and other fields, it is loaded on a porous film or fiber mesh with a highly porous structure. It can overcome the limitations of its traditional loading form and become an innovative idea and approach to solve its application needs.

[0003] With the development of materials science, one-dimensional nanostructured materials such as nanotubes, nanowires, and nanofibers have attracted the interest of many researchers due to their basic scientific research and wide application. In particular, polymer fiber membrane materials are widely used in applications such as filtration materials and catalyst supports due to their extremely high surface area to volume ratio and high membrane porosity. Electrospinning technology is a composite membrane production technology that can produce composite membranes composed of nanometer to micrometer-sized fibers. It can produce ultrafine natural or synthetic polymers, as well as composite fibers of inorganic nanoparticles and polymers. However, traditional solution electrospinning requires the use of organic solvents (such as DMF and THF) to dissolve polymers, which will cause solvent residues to pollute the environment and be costly (reference "Green Chemistry, 2022, 24, 2347-2375"). In addition, when using traditional solution electrospinning to prepare polymer / inorganic material composite fibers, it is easy for inorganic particles to settle or agglomerate due to density differences in the solution during electrospinning, resulting in uneven dispersion inside the fiber.

[0004] Melt electrospinning, a solvent-free, green process for producing ultrafine fibers, overcomes the environmentally unfriendly drawbacks of solution electrospinning and has broad applications in high-performance nonwovens, biomedicine, and high-efficiency filtration. Its basic principle is to heat a solid polymer to a molten state and then use an electric field to stretch the polymer melt into elongated fibers. While melt electrospinning avoids the use of solvents, its application in producing polymer / inorganic composite fibers is limited by the compatibility of the polymer and filler. Currently, molecular sieve and polymer blends are typically in the form of solid blocks or membranes, which prevents the full effectiveness of the molecular sieve's adsorption and catalytic properties from being embedded within the polymer blocks, microspheres, or membranes. Furthermore, when blending molecular sieves with polymer melts, the high surface energy of the molecular sieve as a functional filler and the low polarity of the polymer melt lead to severe aggregation, and the pore structure easily collapses under high-temperature shear. In theory, ultrafine fibers produced using melt electrospinning technology can effectively disperse molecular sieves as carriers, leveraging the porosity and large specific surface area of ​​ultrafine fiber membranes to promote the molecular sieve function of crop cargoes. However, currently, polymer / molecular sieve composite fibers have not been produced using melt electrospinning technology. The reason is that existing melt electrospinning technology has not effectively resolved the contradiction between molecular sieve dispersion, structural stability, and fiber spinnability in the melt electrospinning system. Summary of the Invention

[0005] To address the problems of existing molecular sieves, such as easy agglomeration, poor fixation, and uniform dispersion, the present invention provides a polymer / molecular sieve blended composite fiber material. The fiber exhibits a multi-level pore structure, a high specific surface area, and excellent adsorption properties.

[0006] Another object of the present invention is to provide a melt electrospinning method for preparing polymer / molecular sieve blended composite fiber materials. This method innovatively achieves uniform dispersion and interfacial strengthening of the molecular sieve during the melt electrospinning process through molecular sieve surface modification and compatibilizer design. This solves the problem of irregular fiber morphology and numerous defects caused by poor polymer / molecular sieve dispersion during melt spinning. By imparting a multi-level pore structure to the composite fibers, the overall adsorption and catalytic efficiency of the material is improved. Furthermore, this method has a simple preparation process and is suitable for mass production.

[0007] In addition, through the innovation of the above-mentioned interface modification technology and process collaborative design, the present invention enables this new polymer / molecular sieve blended composite fiber to greatly enhance the function of the molecular sieve, and enables it to be recovered in the form of an integral fiber membrane, avoiding the problem of recovering dispersed particles, thereby expanding the application scenarios of the molecular sieve.

[0008] Another object of the present invention is to provide an application of the above-mentioned polymer / molecular sieve blended composite fiber material.

[0009] The purpose of the present invention is achieved through the following technical solutions:

[0010] The polymer / molecular sieve blended composite fiber proposed in the present invention comprises the following components in parts by weight:

[0011]

[0012] In this material, the molecular sieve can be evenly distributed on the ultrafine polymer fibers to form a composite fiber material.

[0013] Preferably, the polymer / molecular sieve blended composite fiber has a fiber diameter of 0.5-20 μm and contains a multi-level pore structure composed of molecular sieve nanopores and interfiber micropores.

[0014] Preferably, the polymer / molecular sieve blended composite fiber comprises the following raw material components in parts by weight:

[0015]

[0016] More preferably, the polymer / molecular sieve blended composite fiber comprises the following raw material components in parts by weight:

[0017]

[0018] Preferably, the thermoplastic polymer matrix includes at least one of polyethylene (PE), polypropylene (PP), polylactic acid (PLA), polycaprolactone (PCL), polyamide (PA6), polycarbonate (PC), and polyurethane (PU), and its melting point range needs to be compatible with the melt electrospinning process.

[0019] Preferably, the molecular sieve includes at least one of 3A molecular sieve (potassium A type), 4A molecular sieve (sodium A type), 5A molecular sieve (calcium A type), 10Z molecular sieve (calcium Z type), 13Z molecular sieve (sodium Z type), Y type molecular sieve (sodium Y type), sodium mordenite type, etc.

[0020] Preferably, the particle size of the molecular sieve is 0.1-10 μm, and the specific surface area is ≥300 m 2 / g.

[0021] Preferably, the molecular sieve is modified with a coupling agent and then used to prepare a polymer / molecular sieve blended composite fiber. The coupling agent is at least one of a silane coupling agent (such as KH550) or a titanate coupling agent (such as NDZ-201), and the amount of the coupling agent is 1-5% of the mass of the molecular sieve.

[0022] Preferably, the compatibilizer includes at least one of maleic anhydride grafted polyolefin (such as PP-g-MAH), maleic anhydride grafted polycarbonate (PC-g-MAH), reactive compatibilizer (such as isocyanate), etc.

[0023] Preferably, the amount of the compatibilizer is 5-20% of the mass of the molecular sieve. The functional groups of the compatibilizer form chemical bonds with the hydroxyl groups on the surface of the molecular sieve.

[0024] Preferably, the conductive additive is selected from at least one of carbon nanotubes (CNTs), graphene, or conductive carbon black. The conductive additive is used to adjust the conductivity of the melt to optimize the electric field drawing effect.

[0025] The present invention provides a method for preparing polymer / molecular sieve blended composite fibers by melt electrospinning, comprising the following steps:

[0026] S1. Surface modification of molecular sieves: The molecular sieves are dispersed in a solvent, a coupling agent is added, and the mixture is heated to react to obtain a modified molecular sieve having an organic functional group grafted onto the surface;

[0027] S2. Melt blending: melt blending the thermoplastic polymer matrix, modified molecular sieve, compatibilizer and conductive additive, and extruding and granulating to obtain a uniformly dispersed blend masterbatch;

[0028] S3. Melt electrospinning: Add the blended masterbatch into the barrel of the melt electrospinning equipment, heat it to the melting temperature, and then produce the polymer / molecular sieve blended composite fiber by melt electrospinning.

[0029] Preferably, the coupling agent in step S1 is at least one of a silane coupling agent (such as KH550) or a titanate coupling agent (such as NDZ-201), etc.; the amount of the coupling agent is 1-5% of the mass of the molecular sieve.

[0030] Preferably, the heating reaction in step S1 is carried out at a temperature of 60-100° C. and for 1-2 hours.

[0031] Preferably, the solvent in step S1 is an ethanol / water mixed solution with a volume ratio of 9:1.

[0032] Preferably, the equipment used for melt blending in step S2 is a twin-screw extruder temperature, which is partitioned into 10-30°C above the melting point of the thermoplastic polymer matrix (for example, 160-200°C for PLA-based materials and 180-220°C for PP-based materials), a screw speed of 200-400 rpm, an aspect ratio of ≥40:1, and a melt residence time of ≤2 minutes to avoid damage to the molecular sieve pore structure.

[0033] Preferably, the melting temperature in step S3 refers to a temperature 10-30°C higher than the melting point of the polymer matrix, and the melt temperature is 160-220°C.

[0034] Preferably, the parameters of the melt electrospinning in step S3 are: a spinning rate of 0.1-5 mL / h, a high voltage electric field of 20-50 kV applied between the spinneret and the receiving device, and a receiving distance of 10-30 cm.

[0035] Preferably, the diameter of the continuous fibers obtained by the melt electrospinning in step S3 is 0.5-20 μm.

[0036] Preferably, the continuous fibers in step S3 may be collected into non-woven fabrics or oriented fiber mats via a winding device.

[0037] The polymer / molecular sieve blended composite fiber material of the present invention can be applied to the fields of air filtration, catalytic reaction, drying and purification, adsorption separation, etc.

[0038] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0039] (1) Environmental friendliness: The polymer / molecular sieve blended composite fiber material and preparation technology of the present invention are solvent-free throughout the entire process, meeting green manufacturing requirements. In addition, the present invention can innovatively prepare polymer-based ultrafine composite fibers loaded with molecular sieves by blending polymers, molecular sieves, and additives through melt electrospinning technology, which will greatly expand the application of molecular sieves in related fields.

[0040] (2) Dispersibility: In the polymer / molecular sieve blended composite fiber material of the present invention, the molecular sieve can be evenly distributed on the ultrafine polymer fibers. Scanning electron microscope photos show that the molecular sieve is evenly embedded in the material without agglomerates larger than 10 μm (see Appendix Figure 1 ).

[0041] (3) Multi-level pore structure: The polymer / molecular sieve blended composite fiber material of the present invention forms micron-scale pores (1-20 μm) on the surface, and the internal molecular sieve provides nano-scale channels (0.3-2 nm), which synergistically improve the application efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a scanning electron microscope (SEM) image of the cross section of the blended masterbatch prepared in step S2 of Example 1.

[0043] Figure 2 This is a SEM image of the composite fiber prepared in step S3 of Example 1.

[0044] Figure 3 This is an SEM image of the composite fiber prepared in step S3 of Example 3. DETAILED DESCRIPTION

[0045] The present invention will be described in further detail below with reference to the examples and accompanying drawings, but the embodiments of the present invention are not limited thereto. The raw materials involved in the present invention can be purchased directly from the market. For process parameters not specifically noted, conventional techniques can be used.

[0046] Example 1: PP / molecular sieve composite fiber

[0047] Raw materials: 50 parts by weight of polypropylene (PP, melt index 25 g / 10 min), 45 parts by weight of 5A molecular sieve, and 5 parts by weight of maleic anhydride grafted polypropylene (PP-g-MAH).

[0048] Preparation process:

[0049] S1 molecular sieve modification: The molecular sieve was dispersed in an ethanol / water solution, 3% by mass of the molecular sieve was added KH550 silane coupling agent, and the mixture was dried and solidified at 60 ° C for 2 hours to obtain a modified molecular sieve;

[0050] S2. Melt blending: PP, modified molecular sieve, and PP-g-MAH were added to a twin-screw extruder with the temperature zones set to 190°C / 200°C / 210°C and a screw speed of 250 rpm. Extrusion pelletization was performed to obtain a uniformly dispersed blended masterbatch.

[0051] Melt electrospinning: The masterbatch blend was added to a melt electrospinning apparatus with a melt temperature of 220°C, an applied voltage of 25 kV, a receiving distance of 15 cm, and a spinning rate of 1.5 mL / h to produce continuous fibers with a diameter of 8 ± 2 μm.

[0052] Performance testing:

[0053] Adsorption performance: The continuous fiber prepared in step S3 of this embodiment was subjected to water vapor adsorption at 25°C and 90% humidity. The water vapor adsorption capacity of the continuous fiber over 7 days was measured to be 0.12 g / g.

[0054] Structural characterization: 1) The scanning electron microscope (SEM) image of the cross section of the blended masterbatch prepared in step S2 is as follows: Figure 1 As shown, from Figure 1 It can be seen that the molecular sieve is uniformly embedded in the material, and there are no agglomerates larger than 10 μm;

[0055] 2) The SEM image of the composite fiber prepared in step S3 is as follows Figure 2 As shown in the figure, it can be seen that the fiber diameter is about 8-10 μm, the fiber diameter is uniform, the pores between fibers are distributed in the range of 5-20 μm, and the multi-layer fibers form a multi-level pore structure.

[0056] Example 2 PP / molecular sieve composite fiber

[0057] Raw materials: 70 parts by weight of polypropylene (PP, melt index 25 g / 10 min), 25 parts by weight of 4A molecular sieve, 4.5 parts by weight of maleic anhydride grafted polypropylene (PP-g-MAH), and 0.5 parts by weight of multi-walled carbon nanotubes (CNTs).

[0058] Preparation process:

[0059] S1 molecular sieve modification: The molecular sieve was dispersed in an ethanol / water solution, 3% by mass of the molecular sieve was added KH550 silane coupling agent, and the mixture was dried and solidified at 60 ° C for 2 hours to obtain a modified molecular sieve;

[0060] S2. Melt blending: PP, modified molecular sieve, PP-g-MAH, and CNT were added to a twin-screw extruder with the temperature zones set to 190°C / 200°C / 210°C and a screw speed of 250 rpm. Extrusion pelletization was performed to obtain a uniformly dispersed blend masterbatch.

[0061] Melt electrospinning: The masterbatch blend was added to a melt electrospinning apparatus with a melt temperature of 220°C, an applied voltage of 30 kV, a receiving distance of 20 cm, and a spinning rate of 1.2 mL / h to produce continuous fibers with a diameter of 4 ± 1 μm.

[0062] Performance testing:

[0063] Adsorption performance: The continuous fiber prepared in step S3 of this embodiment was subjected to an adsorption test on toluene vapor at 25°C, and the adsorption capacity for 24 hours was measured to be 0.65 g / g;

[0064] Structural characterization: SEM images show that the continuous fibers prepared in step S3 of this embodiment have uniform diameters, and the pores between the fibers are distributed in the range of 5-20 μm.

[0065] Example 3 PLA / molecular sieve composite fiber

[0066] Raw materials: 80 parts by weight of polylactic acid (PLA, molecular weight 100,000), 18 parts by weight of 13Z molecular sieve, and 2 parts by weight of diphenylmethane diisocyanate.

[0067] Preparation process:

[0068] S1. Molecular sieve modification: The molecular sieve was mixed with a titanate coupling agent NDZ-201 at a mass ratio of 100:2 and stirred at 80°C for 1 hour to obtain a modified molecular sieve;

[0069] S2. Melt blending: PLA, modified molecular sieve, and diphenylmethane diisocyanate were blended in a twin-screw extruder at 175°C / 185°C / 195°C, a screw speed of 300 rpm, and extruded into pellets to obtain a uniformly dispersed blend masterbatch;

[0070] Melt electrospinning: The masterbatch blend was added to a melt electrospinning apparatus with a melt temperature of 200°C, an applied voltage of 25 kV, a receiving distance of 15 cm, and a spinning rate of 1.0 mL / h to produce continuous fibers with a diameter of 5 ± 1 μm.

[0071] Performance testing:

[0072] Catalytic Performance: The continuous fiber prepared in step S3 of this example was used to catalyze the degradation of a methylene blue dye aqueous solution (solution concentration: 1.5 mg / mL). Under visible light irradiation, the degradation rate of methylene blue reached 95% within 2 hours (compared to 20% for pure PLA fiber).

[0073] Structural characterization: The SEM image of the composite fiber prepared in step S3 is as follows: Figure 3 As shown in the figure, it can be seen that the fiber diameter is uniform and the pores between fibers are distributed in the range of 5-20 μm.

[0074] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A polymer / molecular sieve blended composite fiber, characterized in that: The raw materials for its preparation include the following components by weight:

2. The polymer / molecular sieve blended composite fiber according to claim 1, characterized in that: The fiber diameter of the polymer / molecular sieve blended composite fiber is 0.5-20 μm, and the inside contains a multi-level pore structure composed of molecular sieve nanopores and interfiber micropores.

3. The polymer / molecular sieve blended composite fiber according to claim 1, characterized in that: The thermoplastic polymer matrix includes at least one of polyethylene, polypropylene, polylactic acid, polycaprolactone, polyamide, polycarbonate, and polyurethane.

4. The polymer / molecular sieve blended composite fiber according to claim 1, characterized in that: The molecular sieve includes at least one of 3A molecular sieve, 4A molecular sieve, 5A molecular sieve, 10Z molecular sieve, 13Z molecular sieve, Y-type molecular sieve, and sodium mordenite; The particle size of the molecular sieve is 0.1-10 μm, and the specific surface area is ≥300 m 2 / g.

5. The polymer / molecular sieve blended composite fiber according to claim 1, characterized in that: The compatibilizer includes at least one of maleic anhydride grafted polyolefin, maleic anhydride grafted polycarbonate, and a reactive compatibilizer.

6. The polymer / molecular sieve blended composite fiber according to claim 1, characterized in that: The conductive additive is selected from at least one of carbon nanotubes, graphene or conductive carbon black.

7. The method for preparing the polymer / molecular sieve blended composite fiber according to any one of claims 1 to 6, characterized in that: The steps include: S1. The molecular sieve is dispersed in a solvent, a coupling agent is added and mixed, and then heated to react to obtain a modified molecular sieve having an organic functional group grafted onto the surface; S2. The thermoplastic polymer matrix, modified molecular sieve, compatibilizer and conductive additive are melt-blended and extruded into granules to obtain a uniformly dispersed masterbatch; S3. Add the blended masterbatch into a melt electrospinning device, heat it to a melting temperature, and then produce the polymer / molecular sieve blended composite fiber by melt electrospinning.

8. The preparation method according to claim 7, characterized in that The coupling agent in step S1 is a silane coupling agent or a titanate coupling agent; the amount of the coupling agent is 1-5% of the mass of the molecular sieve; The temperature of the heating reaction in step S1 is 60-100°C; The equipment used for the melt blending in step S2 is a twin-screw extruder with a screw speed of 200-400 rpm, an aspect ratio of ≥40:1, and a melt residence time of ≤2 minutes.

9. The preparation method according to claim 7, characterized in that The parameters of the melt electrospinning in step S3 are: melt temperature of 160-220° C., spinning rate of 0.1-5 mL / h, application of a 20-50 kV high voltage electric field between the spinneret and the receiving device, and a receiving distance of 10-30 cm.

10. Use of the polymer / molecular sieve blended composite fiber according to any one of claims 1 to 6 in the fields of air filtration, catalytic reaction, drying and purification, and adsorption separation.

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