Nanometer and micrometer cross-scale inlaying composite net forming method

Abstract

The invention discloses a nanometer and micrometer cross-scale inlaying composite web forming method which comprises the following steps: S1, preparing raw materials and equipment: adopting PET (Polyethylene Terephthalate) short fibers as micrometer fiber raw materials and adopting DMF (Dimethyl Formamide) (the purity is greater than or equal to 99.5%) and PAN (Polyacrylonitrile) powder with the molecular weight of 80000 + / -5000 as nanometer fiber raw materials, the equipment comprises a carding machine, a photocuring 3D printer with the precision of 0.05 mm, an ultrafast laser, a high-frequency piezoelectric controller and a micro-tensile testing machine; s2, carding the micron fibers into a framework; s3, on-line preparation of nanofibers; s4, cross-scale fiber online inlaying is carried out; s5, low-temperature hot-pressing shaping is conducted, specifically, the primary product of the composite fiber web is fed into a hot-pressing roller, low-temperature hot-pressing is conducted for 15 s at the temperature of 60 DEG C and the pressure of 0.15 MPa, the nanometer and micrometer inlaid structures are cured, and fiber falling in subsequent processing is avoided; and finally, winding by a winding device to obtain a composite fiber web finished product with the breadth of 1500mm. According to the invention, the industrial common problems that the breadth of the existing cross-scale fiber web is smaller than 1m, nano / micron fibers are not uniformly mixed and large-scale production cannot be realized can be solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of textile functional material preparation, and particularly relates to a nano-micron cross-scale inlaid composite webbing method. BACKGROUND

[0002] The nano / micron cross-scale fiber assembly has important application value in multiple fields due to extremely high specific surface area, excellent mechanical properties and adjustable pore structure. However, the existing technology has three core defects: 1. width limitation: most methods are still limited to small-width experimental products (<1m), and there is a lack of systematic solution for the coordinated forming of nano / micron cross-scale fibers in a meter-level wide range; 2. mixing difficulty: the nano fibers have large specific surface area and strong agglomeration, and are prone to electrostatic adsorption or Van der Waals adsorption when directly mixed and carded with micron fibers, so it is difficult to form a uniform fiber web; 3. lack of integration: there is no online coordinated device for “nano fiber preparation-micron fiber carding-inlaid composite”, and offline mixing is required, which is low in production efficiency and unstable in performance. These defects result in that the cross-scale fiber assembly cannot meet the needs of large-scale production of high-value-added functional yarns and high-end functional textile fabrics.

[0003] Therefore, in view of the above technical problems, it is necessary to provide a nano-micron cross-scale inlaid composite webbing method.

[0004] The information disclosed in this part of the background is only intended to increase the understanding of the overall background of the application, and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art. SUMMARY

[0005] The purpose of the present application is to provide a nano-micron cross-scale inlaid composite webbing method, which can solve the industry common problems of narrow width (<1m) of cross-scale fiber webbing, uneven mixing of nano / micron fibers and inability to produce on a large scale.

[0006] In order to achieve the above-mentioned purpose, the technical scheme provided by an embodiment of the present application is as follows:

[0007] A nano-micron cross-scale inlaid composite webbing method, comprising the following steps:

[0008] S1, raw material and equipment preparation,

[0009] The micron fiber raw material is PET staple fiber,

[0010] The nano fiber raw material is DMF and PAN powder with a molecular weight of 80000,

[0011] Equipment: carding machine, light-curing 3D printer with a precision of 0.05mm, ultrafast laser, high-frequency piezoelectric controller and micro-tension testing machine;

[0012] S2, carding micron fibers into a skeleton, first send the polyester micron fibers into the carding machine, control the speed of the cylinder 400 r / min, the speed of the doffer 50 r / min, form a uniform micron skeleton web with a surface density of 25 g / m² on the XY plane, and convey it to the online coupling structure through the guide roller;

[0013] S3, online preparation of nanofibers, configure a 13wt% PAN / DMF solution, stir at 100°C for 3h, adjust the viscosity to 700cP, and then stand for 2h, inject into the pre-oriented micro channel; start the high-frequency piezoelectric module and the jet stretching module, the PAN solution is extruded through a 4μm spinneret, and then stretched by air flow into nanofibers with a diameter of 180±15nm;

[0014] S4, online embedding of cross-scale fibers, through the reciprocating vibration mechanism of the online coupling structure, the nanofibers are vertically embedded in the micron skeleton web along the Z direction, and the web speed is controlled at 100m / min; during the process, the uniformity of the web is monitored in real time by a CCD camera to ensure that there is no local aggregation, and a composite web primary product is obtained;

[0015] S5, low-temperature hot pressing, the composite web primary product is sent into the hot pressing roller, and the low-temperature hot pressing is carried out at 60°C and 0.15MPa for 15s, the nanometer and micron embedded structure is solidified, and the fibers are prevented from falling off during subsequent processing; finally, it is wound up through the winding device to obtain a 1500mm wide composite web finished product.

[0016] In one or more embodiments of the present application, the pre-oriented micro channel in step S3 is formed by light-cured 3D printing, the cross section of the flow channel is 2mm×1.5mm, the length is 50mm, the stable flow of polyacrylonitrile polymer solution is ensured, local retention is avoided, and the inner surface of the pre-oriented micro channel is modified by plasma to optimize the wetting angle to 55-65°.

[0017] In one or more embodiments of the present application, the online coupling structure in step S2 includes a piezoelectric jet unit and a matched eccentric wheel type reciprocating vibration mechanism, 8 sets of piezoelectric jet units are arranged in parallel along the 1500mm width, and the distance between every two sets of piezoelectric jet units is 187.5mm, and the piezoelectric jet unit is driven by a synchronous belt with a transmission ratio of 1:5; the amplitude of the matched eccentric wheel type reciprocating vibration mechanism is 8mm, and the frequency is 1Hz, which ensures that the nanofibers are uniformly scattered to the micron fiber skeleton along the width.

[0018] In one or more embodiments of the present application, the jet stretching module in step S3 is a curved hole type designed based on the three-dimensional Navier-Stokes equation of turbulent flow, and a gas pressure stabilizing valve is arranged in the hole, the compressed air flow is 0.3-0.4m³ / h, the air pressure is 0.3-0.35MPa, and the extruded PAN solution is instantaneously stretched into nanofibers with a diameter of ≤200nm.

[0019] In one or more embodiments of the present application, the jet stretching module in step S3 works at a flow rate of 0.35 m³ / h and a gas pressure of 0.32 MPa.

[0020] In one or more embodiments of the present application, the high-frequency piezoelectric module in step S3 is composed of four barium ferrite piezoelectric ceramics connected in series, and has a working frequency of 3-8 kHz, a voltage of 100-180 V, a maximum displacement of 0.3 mm, and a real-time matching of PAN solution viscosity through a piezoelectric controller to provide stable extrusion power.

[0021] In one or more embodiments of the present application, the axis of the curved surface of the mold is the SP axis, and the high-frequency piezoelectric module has a working frequency of 5 kHz and a voltage of 150 V when it is in operation.

[0022] In one or more embodiments of the present application, the 4 μm spinning hole in step S3 is obtained by superfast laser thermal coupling processing, and has a laser power of 50 W and a processing time of 8 s / hole during processing, and a heat-affected zone ≤5 μm; the 4 μm spinning hole has a three-section structure of "75° flared-80 μm straight hole-60° constricted", and the inner wall of the hole is plasma polished to prevent PAN solution from remaining and blocking.

[0023] Compared with the prior art, the one-nano-micron cross-scale inlaid composite webbing method has the following beneficial effects:

[0024] 1. The one-nano-micron cross-scale inlaid composite webbing method adopts a pre-oriented micro-channel assembly, a photo-curing method, a 3D printing forming method, a high-frequency piezoelectric module, a 4 μm spinning hole assembly, a jet stretching module, and an online coupling structure (1500 mm web width arrangement of 8 piezoelectric units), and realizes the four steps of "micron carding-nano preparation-online inlaying-thermal setting" through the one-nano-micron cross-scale inlaid composite webbing method, breaks through the width limitation of existing devices, realizes a 1500 mm width and above of the one-nano-micron cross-scale inlaid composite webbing method, and meets the large-scale production demand of ≥14400 m² per day of the one-nano-micron cross-scale inlaid composite webbing method;

[0025] 2. The online cooperation of nano-fiber preparation and micron-fiber carding is realized, the problem of nano-fiber agglomeration is solved, and the inlaying uniformity is ≥85%;

[0026] 3. The composite fiber web has mechanical properties (tensile strength ≥25 MPa) and air permeability (≥600 mm / s) to adapt to high-end functional textile applications;

[0027] 4. The composite fiber web can be compatible with polypropylene / PAN, polyester / PAN, nylon / PAN, cellulose cotton yarn / PAN, and other 5 kinds of cross-scale fibers, providing core technical support for the high-end functional textile industry;

[0028] 5. The integrated online webbing process saves the offline mixing process, reduces production energy consumption by 30%, reduces the spinning hole blockage rate to ≤1%, extends the maintenance cycle to 24 months, and reduces the comprehensive cost by 25%. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to make the technical solutions in the embodiments or the prior art clearer, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0030] Figure 1 The key technology and mechanism of the cross-scale fiber assembly controllable forming manufacturing of the present application;

[0031] Figure 2 The experimental data of the present application compared with the prior art;

[0032] Figure 3 The nanometer PAN and micrometer PET fiber inlay structure of the present application;

[0033] Figure 4 The nanometer PAN fiber and PP fiber inlay structure of the present application. DETAILED DESCRIPTION

[0034] In order to make the technical solutions in the embodiments or the prior art clearer, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0035] To solve the existing cross-scale fiber web width narrow (<1m), nanometer / micron fiber mixed uneven, unable to scale production of industry common problems. The embodiment provides a web forming method, the web forming speed reaches 100m / min, the nanofiber diameter is ≤200nm, and the mosaic uniformity is ≥85%. The application can be compatible with 5 types of cross-scale fibers, and provides core technology for large-scale production of high-end functional textiles

[0036] As shown in Figure 1 The schematic diagram of the key technology and mechanism research of the cross-scale fiber assembly controllable forming manufacturing (micro-channel design and 3D printing structure assembly, high-frequency voltage module design, jet module design and 3D printing structure assembly, fiber air jet head design, nanofiber preparation and carding, nanometer / micron fiber mosaic structure 6 key technology modules) is shown.

[0037] More specifically, the embodiment is a 1500mm nanometer, micron cross-scale mosaic composite web forming method, which is realized by four steps of "micron carding-nanometer preparation-online mosaic-heat setting", breaks through the existing device width limit, realizes 1500mm and above wide web forming, meets the large-scale production demand of ≥14400m² per day, including the following steps:

[0038] S1, raw material and equipment preparation,

[0039] The micron fiber raw material adopts PET short fiber, the diameter is 20μm, the length is 38mm, and the breaking strength is 4.5cN / dtex;

[0040] Nanofiber raw material: DMF (analytical pure) and PAN powder with molecular weight of 80000 are used,

[0041] Equipment: carding machine, precision 0.05mm photocuring 3D printer, ultrafast laser (pulse width 10ps, wavelength 1064nm), high-frequency piezoelectric controller and micro-tension testing machine;

[0042] S2, carding the micron fiber into a skeleton, first send the polyester micron fiber into the carding machine, control the speed of the cylinder 400r / min, the speed of the doffer 50r / min, form a uniform micron skeleton web with a surface density of 25g / m² on the XY plane, and convey it to the online coupling structure through the guide roller;

[0043] The online coupling structure comprises a piezoelectric jet unit and a matched eccentric wheel type reciprocating vibration mechanism, 8 sets of piezoelectric jet units are arranged in parallel along a width of 1500 mm, the distance between every two sets of piezoelectric jet units is 187.5 mm, and the piezoelectric jet unit is driven by a synchronous belt with a transmission ratio of 1:5; the amplitude of the matched eccentric wheel type reciprocating vibration mechanism is 8 mm, and the frequency is 1 Hz, so that the nanofiber is uniformly scattered to the micron fiber skeleton along the width;

[0044] S3, online preparation of nanofiber, 13wt% PAN / DMF solution is prepared, stirred at 100℃ for 3h, the viscosity is adjusted to 700cP (tested by rotary viscometer NDJ-5S), then the solution is left for 2h, and then injected into the pre-oriented microchannel; the high-frequency piezoelectric module and the jet stretching module are started, and the PAN solution is extruded through the 4μm spinneret, and then stretched by the airflow into nanofiber with a diameter of 180±15nm;

[0045] The pre-oriented microchannel is formed by light-cured 3D printing, the cross section of the microchannel is 2mm×1.5mm, and the length is 50mm, so that the polyacrylonitrile polymer solution can flow stably and avoid local retention, and the inner surface of the pre-oriented microchannel is modified by plasma to optimize the wetting angle to 55-65°, and in this embodiment, the pre-oriented microchannel is printed by 3D printing with a layer thickness of 0.1mm and a wetting angle of 60°;

[0046] The jet stretching module is designed based on the three-dimensional Navier-Stokes equation of turbulent flow, and a gas pressure stabilizing valve is arranged in the hole, the compressed air flow is 0.3-0.4m³ / h, and the air pressure is 0.3-0.35MPa, so that the extruded PAN solution is instantaneously stretched into nanofiber with a diameter of ≤200nm;

[0047] The high-frequency piezoelectric module is composed of 4 pieces of barium ferrite piezoelectric ceramic connected in series, the working frequency is 3-8kHz, the voltage is 100-180V, the maximum displacement is 0.3mm, the piezoelectric controller is used to match the viscosity of the PAN solution in real time to provide stable extrusion power, the size of the ferrite ceramic is 10mm×5mm×2mm, and the frequency and voltage are accurately matched through the piezoelectric controller;

[0048] The 4μm spinneret is obtained by superfast laser thermal coupling machining, the laser power is 50W during machining, the machining time is 8s / hole, and the heat affected zone is ≤5μm; the hole of the 4μm spinneret has a three-section structure of “75° flaring-80μm straight hole-60° conical”, and the inner wall of the hole is polished by plasma to prevent the PAN solution from remaining and blocking;

[0049] S4, cross-scale fiber online inlay, through the reciprocating vibration mechanism of the online coupling structure, the nanofiber is inlaid in the micron skeleton fiber web along the Z direction vertically, the webbing speed is controlled to be 100 m / min; during the period, the uniformity of the fiber web is monitored in real time through the CCD camera, it is ensured that there is no local agglomeration, the composite fiber web preliminary product is obtained, the webbing process needs to be continuously operated for 8 hours, there is no spinneret blockage, the width of the fiber web is stable at 1500 mm (tested by a laser width tester), and the edge is free of defects

[0050] S5, low-temperature hot pressing, the composite fiber web preliminary product is sent into a hot pressing roller, 60℃, 0.15 MPa low-temperature hot pressing is adopted for 15 s, the nanometer and micron inlay structure is solidified, fiber falling off in subsequent processing is avoided, finally, the product is wound through a winding device, and a 1500 mm width composite fiber web product is obtained.

[0051] In the embodiment, when the jet drafting module in step S3 works, the flow is 0.35 m³ / h, and the air pressure is 0.32 MPa; the axis of the curved surface of the mold is the SP axis; when the high-frequency piezoelectric module works, the working frequency is 5 kHz, and the voltage is 150 V.

[0052] The obtained product is subjected to structure detection: scanning electron microscopy (SU8010) observation (see Figure 3 ), the nanometer PAN fiber (180±15 nm) is uniformly inlaid in the gap between the micron PET fibers, the inlaying density is 110 roots / mm², Figure 3 , which shows the inlaying state of the nanofiber (180±15 nm) and the micron PET fiber (20 μm), and proves the uniformity of webbing.

[0053] In combination with Figure 3 , reference is made to Figure 3 , which is an SEM graph of the inlaying structure of the nanometer PAN fiber and the PP fiber (scale 10 μm), the inlaying morphology of the 180 nm PAN nanofiber and the PP micron fiber is marked, the compatibility of the device of the application to the PP / PAN system is proved, the device of the application can be compatible with 5 types of cross-scale fibers such as PP / PAN, PET / PAN, nylon / PAN, cellulose cotton yarn / PAN and spandex / PAN, and can provide core technical support for the high-end functional textile industry.

[0054] Performance detection: according to the GB / T 3923.1-2013 standard, the tensile strength is 25 MPa, the elongation at break is 18%, the air permeability is 600 mm / s, the thickness is 0.2 mm, and the deviation is ≤5% by using a micro-tensile testing machine, an air permeability tester (YG461E) and a thickness tester; various experimental data are referred to Figure 2 .

[0055] Furthermore, it should be understood that although the specification is described in terms of embodiments, not every embodiment includes every feature described. The specification can include implicit combinations of explicitly mentioned features and / or explicit combinations of implicitely mentioned features. Each embodiment depends on the explicit combinations of features and / or the implicit combinations of features made specifically within that embodiment, and each such embodiment can be combined with every other such embodiment to create further embodiments.

Claims

1. A nano-micro cross-scale tessellation composite network method, characterized in that, The method comprises the following steps: S1, raw material and equipment preparation, The micron fiber raw material is PET short fiber, The nanometer fiber raw material is PAN powder with a molecular weight of 80000 and DMF, The equipment is a carding machine, a light-curing 3D printer with a precision of 0.05 mm, an ultrafast laser, a high-frequency piezoelectric controller and a micro-tension testing machine; S2, carding the micron fibers into a skeleton, first, send the polyester micron fibers into the carding machine, control the speed of the cylinder to 400 r / min and the speed of the doffer to 50 r / min, form a uniform micron skeleton web with a surface density of 25 g / m² on the XY plane, and convey it to the online coupling structure through the guide roller; S3, online preparation of nanometer fibers, configure a 13wt% PAN / DMF solution, stir at 100°C for 3h, adjust the viscosity to 700cP, and then stand for 2h to remove bubbles, and inject it into the pre-oriented micro-channel; start the high-frequency piezoelectric module and the jet stretching module, and the PAN solution is extruded through a 4μm nozzle and stretched into nanofibers with a diameter of 180±15nm by air flow; S4, online embedding of fibers with different scales, through the reciprocating vibration mechanism of the online coupling structure, the nanofibers are vertically embedded in the micron skeleton web along the Z direction, and the web forming speed is controlled to 100m / min; during the process, the uniformity of the web is monitored in real time by a CCD camera to ensure that there is no local aggregation, and a composite web is obtained; S5, low-temperature hot pressing, the composite web is sent into the hot pressing roller, and the low-temperature hot pressing is carried out at 60°C and 0.15MPa for 15s to solidify the nanometer and micron embedded structure and avoid fiber shedding in subsequent processing; finally, the product is wound up through the winding device to obtain a 1500mm wide composite web product.

2. The method of claim 1, wherein, The pre-oriented micro-channel in step S3 is formed by light-curing 3D printing, the cross section of the channel is 2mm×1.5mm, and the length is 50mm, which ensures the stable flow of polyacrylonitrile polymer solution and avoids local retention, and the inner surface of the pre-oriented micro-channel is modified by plasma to optimize the wetting angle to 55-65°.

3. The method of claim 2, wherein, The online coupling structure in step S2 includes a piezoelectric jet unit and a matched eccentric wheel type reciprocating vibration mechanism, 8 sets of piezoelectric jet units are arranged in parallel along the 1500mm width, and the distance between every two sets of piezoelectric jet units is 187.5mm, and the piezoelectric jet unit is driven by a synchronous belt with a transmission ratio of 1:5; the amplitude of the matched eccentric wheel type reciprocating vibration mechanism is 8mm, and the frequency is 1Hz, which ensures that the nanofibers are evenly scattered to the micron fiber skeleton along the width.

4. The method of claim 3, wherein, The jet stretching module in step S3 is designed based on the three-dimensional Navier-Stokes equation of turbulent flow, and a gas pressure stabilizing valve is arranged in the hole, the compressed air flow is 0.3-0.4m³ / h, and the air pressure is 0.3-0.35MPa, which can instantaneously stretch the extruded PAN solution into nanofibers with a diameter of ≤200nm.

5. The method of claim 4, wherein, When the jet stretching module in step S3 works, the flow is 0.35m³ / h, and the air pressure is 0.32MPa.

6. The method of claim 3, wherein, The high-frequency piezoelectric module in step S3 is composed of 4 pieces of barium ferrite piezoelectric ceramics in series, has a working frequency of 3-8 kHz, a voltage of 100-180 V, a maximum displacement of 0.3 mm, and provides stable extrusion power by real-time matching of the viscosity of the PAN solution through a piezoelectric controller.

7. The method of claim 6, wherein, The high-frequency piezoelectric module has a working frequency of 5 kHz and a voltage of 150 V in actual work.

8. The method of claim 3, wherein, The 4-μm spinning hole in step S3 is obtained by superfast laser thermal coupling processing, has a laser power of 50 W and a processing time of 8 s / hole, and has a heat-affected zone of ≤5 μm; the hole channel of the 4-μm spinning hole has a three-section structure of "75° flaring-80-μm straight hole-60° necking", and the inner wall of the hole channel is plasma polished to prevent residual PAN solution from blocking.

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