A melt-blown spinneret and preparation method thereof

Abstract

The present invention discloses a meltblown spinneret and a preparation method thereof, and relates to the technical field of spinnerets. The meltblown spinneret of the present invention has a double-sided heterogeneous integrated structure, one side of which is the end face where the feed port is located, and the other side is the end face where the discharge port is located; the component of the part where the feed port is located is at least one of 4Cr13, 316L, and SUS304; the component of the part where the discharge port is located is a mixture of the component of the part where the feed port is located and ceramic powder; the ceramic powder contains at least one of Al2O3, ZrO2, and TiB2. The present invention can reduce the surface tension between the discharge port surface and the droplets by selecting the components of the feed port and the discharge port of the meltblown spinneret, and can also reduce the thermal conductivity of the discharge port end face, thereby promoting the smooth flow of the droplets at the feed port end face and the solidification and smooth separation at the discharge port end face.

Description

Technical Field

[0001] The invention relates to the technical field of spinnerets, and in particular to a melt-blown spinneret and a preparation method thereof. Background Art

[0002] The meltblown die head is the core component of the main meltblown production equipment for producing meltblown cloth and other chemical fiber products. The die head generally includes a die head body, a spinneret and an air plate. The function of the spinneret is to convert the viscous polymer melt or solution into a thin flow with a specific cross-sectional shape through micropores with a specific shape, and obtain the filaments after solidification by a coagulation medium such as air or a coagulation bath. The spinneret is a precision part on a chemical fiber spinning machine. Its material, shape and physical size are important conditions to ensure the high quality of fiber products. The two sides of the spinneret in the working state are in contact with different media. The temperature of the side where the discharge port is located is lower, while the temperature of the side where the feed port is located is higher. The relatively low temperature environment on the side of the discharge port will reduce the temperature of the side of the feed port, which is not conducive to the flow of the liquid in the micropores, so it may also cause condensation and blockage of the holes. On the other hand, there is surface tension between the surface where the discharge port of the spinneret is located and the droplets of the production material. The surface tension between the two is an important factor affecting the smooth separation of the two, and directly affects the spinnability of the fiber. The smaller the surface tension between them, the smoother the separation of the two. Therefore, the surface material of the spinneret outlet has a significant impact on the formation of the primary fiber, especially for advanced dry-wet spinning, this factor is particularly important. If the surface tension between the two is large, the liquid will flow on the surface of the spinneret, not only unable to form new filaments, but also stick to the surface of the spinneret, affecting the normal spinning of other surrounding spinnerets, resulting in all broken ends. Therefore, the material selection of the spinneret is particularly important. At present, most spinnerets at home and abroad are made of uniform stainless steel, and spinnerets made of a single material will have the above-mentioned shortcomings to a greater or lesser extent.

[0003] The core problem of spinneret manufacturing is the problem of dense micro-hole processing. Depending on the aperture and shape of the micro-hole, the fiber diameter and cross-sectional shape are different, and therefore the quality and application are also different. With the increasing quality requirements for meltblown cloth and chemical fiber products, the shape of these micro-holes has become more and more complex, and has developed from simple circular holes to more complex special-shaped holes. The production and processing of these fine holes are crucial. Their geometric shape and surface smoothness directly affect the flow characteristics of the melt, and are closely related to the production efficiency and quality of meltblown cloth and chemical fiber products. These micro-holes are not only shaped, but also have a certain depth. Based on the existing technology, the commonly used solutions for spinneret processing micro-holes are electrospark processing, laser processing, and micro-drilling processing. The processing is difficult and the processing time often takes several months. As people pay more attention to the living environment and sanitary conditions, people's demand for meltblown cloth and chemical fiber products is increasing, especially the demand for meltblown cloth used to produce protective masks. Therefore, the production and preparation of high-quality meltblown spinnerets is particularly important. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a melt-blown spinneret with a double-sided heterogeneous integrated structure and a preparation method thereof.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a melt-blown spinneret having a double-sided heterogeneous integrated structure, one side of which is the end face where the feed port is located, and the other side is the end face where the discharge port is located; the composition of the part where the feed port is located is at least one of 4Cr13, 316L, and SUS304; the composition of the part where the discharge port is located is a mixture of the composition of the part where the feed port is located and ceramic powder; the ceramic powder contains at least one of Al2O3, ZrO2, and TiB2.

[0006] The applicant of the present invention can ensure that the feed liquid will not block the hole and can also ensure a higher spinning rate by selecting the components of the feed port and the discharge port.

[0007] Preferably, the mass fraction of the ceramic powder in the component of the portion where the discharge port is located is 5-10%.

[0008] The purpose of controlling the mass fraction of ceramic powder to 5-10% is to ensure that the prepared melt-blown spinneret has good mechanical properties and will not cause the spinneret to crack due to the different compositions of the feed port and the discharge port. At the same time, it can also ensure that the spinneret can be quickly separated from the spinning liquid to improve the spinning efficiency.

[0009] Preferably, a guide hole is provided at the feed inlet, and a group of fine spinneret holes is provided at the discharge outlet.

[0010] Preferably, the guide holes are composed of conical guide holes and cylindrical guide holes from top to bottom, respectively, the cylindrical guide holes are connected to the micro-spinneret holes below, the micro-spinneret holes include at least one of a circular hole and at least one non-circular shaped hole, and the cross-section of the shaped hole includes at least one of a triangle, a regular pentagon, a regular hexagon, and a regular octagon.

[0011] Preferably, the conical guide hole has an inclination angle of 25 to 35° and a depth of 1.5 to 2.5 mm.

[0012] The setting of the conical guide hole can increase the feeding area and speed up the feeding rate. In the structure described in the present invention, limiting the inclination angle and depth of the conical guide hole as mentioned above can increase the spinning rate while ensuring the spinning quality remains unchanged and the spinning is not interrupted.

[0013] Preferably, the diameter of the inscribed circle of the irregular hole is the same as that of the circular hole, both of which are 0.2-0.3 mm; the fine spinneret holes are distributed on a circle coaxial with the guide hole, and the diameter of the circle is half the diameter of the cylindrical guide hole.

[0014] Preferably, the depth of the fine spinneret hole is 20 times the diameter of the inscribed circle of the special-shaped hole or the circular hole.

[0015] Preferably, the diameter of the cylindrical flow guide hole is 20 times the diameter of the inscribed circle of the special-shaped hole or the circular hole; and the center distance between two adjacent cylindrical flow guide holes is the diameter of the cylindrical flow guide hole plus 4-5 mm.

[0016] Preferably, the ratio of the total depth of the conical guide hole and the cylindrical guide hole to the diameter of the cylindrical guide hole is 1:1.

[0017] The purpose of limiting the aspect ratio of the spinneret, the diameter ratio of the inscribed circle of the cylindrical guide hole and the special-shaped hole or the circular hole, and the depth of the guide hole and the diameter ratio of the cylindrical guide hole is to further increase the spinning rate.

[0018] In addition, the present invention also discloses a method for preparing the meltblown spinneret, comprising the following steps:

[0019] (1) Printing a double-sided heterogeneous integrated structure using a high-energy beam 3D printing process; the high-energy beam 3D printing process includes: electron beam additive manufacturing (EBAM), laser near-net shaping (LENS), laser metal forming (LMF), and selective laser melting (SLM) technology;

[0020] (2) The above-mentioned double-sided heterogeneous integrated structure is polished by abrasive flow polishing technology to make the average roughness of its surface and interior R a Less than 0.4 μm, the melt-blowing spinneret is obtained.

[0021] Abrasive flow polishing technology, also known as fluid polishing technology (AFM), is an advanced surface finishing technology. It mainly uses chemically inactive, non-corrosive flexible abrasives, and squeezes the viscoelastic flexible abrasives to flow with the workpiece, so as to achieve the purpose of removing burrs in the inner cavity, finishing and polishing the inner surface, and processing fillets. Especially for the inner surface, guide grooves, long holes, cavities, etc. of the workpiece, which are difficult to process using traditional polishing processes, for workpieces with complex internal shapes, fluid polishing is an ideal, efficient and fine polishing and deburring process. Fluid polishing performs deburring, filleting and polishing of different areas of the workpiece (including hidden and difficult-to-process areas) at the same time, which can be completed at one time, reducing the number of processing steps. When using the abrasive flow processing technology, it is necessary to use appropriate abrasive temperature, flow rate and viscosity to obtain the expected effect. Combined with the characteristics of the spinneret, the abrasive flow polishing process is used to post-process the spinneret prepared by 3D printing, which can not only remove the powder remaining in the pores during the printing process, but also make the inner wall of the pores smoother and the spinneret smoother, thereby extending the service life of the mold.

[0022] Preferably, in step (1), the high energy beam 3D printing process is as follows:

[0023] A. Weigh the raw material powder and sieve it to obtain a powder with a particle size of 15-53 μm;

[0024] B. Ball milling and mixing the powders required for the discharge port;

[0025] C. Drying powder;

[0026] D. Printing with a selective laser melting 3D printer: Use SolidWorks software to build a three-dimensional model, import the three-dimensional model into the printing system, and use Magic software to add processing allowance and slice it; use laser to melt the powder in the parts where the discharge port and the feed port are located in turn. During the printing process, the laser power of the discharge port is 155-165W, the spot diameter is 90-110μm, the scanning speed is 1350-1450mm / s, the powder thickness is 0.025-0.035mm, and the scanning spacing is 0.075-0.085mm; the laser power of the feed port is 135-145W, the spot diameter is 95-105μm, the scanning speed is 1350-1450mm / s, the powder thickness is 0.025-0.035mm, and the scanning spacing is 0.075-0.085mm; the substrate temperature is 90-110℃.

[0027] Selective laser melting 3D printing technology has the advantage of high-precision one-piece molding. Its research on metal preparation has made great progress, and the use of this technology to manufacture porous alloys has become increasingly mature. The use of 3D printing technology can achieve customized preparation of porous structural parts of different specifications. Its production cycle is short and the fine pores are precisely formed. It can greatly alleviate or even solve the problem of long processing time for preparing meltblown die heads using existing technologies, and promote the development of the chemical fiber industry.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The spinneret with a double-sided heterogeneous integrated structure obtained by the above design of the present invention has upper and lower end faces of different materials designed for the different working temperatures of the feed port end face and the discharge port end face of the spinneret, and ceramic material is added to the end face where the discharge port is located, which can not only reduce the surface tension between the discharge port surface and the droplets, but also reduce the thermal conductivity of the end face, thereby promoting the smooth flow of droplets on the feed port end face and the solidification and smooth separation on the discharge port end face; on the other hand, the designed guide hole can also increase the flow rate of the liquid material and improve the production efficiency; in addition, the designed fine outlet hole with a special-shaped cross-section can provide a solution to meet the increasingly higher and more complex quality requirements of meltblown cloth and chemical fiber products.

[0030] (2) The present invention also provides a method for preparing a meltblown spinneret, which adopts high-energy beam 3D printing integrated molding technology and abrasive flow polishing post-processing technology. It can not only solve the problems of difficult processing of special-shaped micro-pore structures using traditional methods and long processing cycles, but also improve the production efficiency and quality of the spinneret, thereby alleviating the pressure on the meltblown cloth and chemical fiber industry, and at the same time can also broaden the practical application field of high-energy beam 3D printing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural diagram of the melt-blown spinneret of the present invention;

[0032] Figure 2 The feed port end view and enlarged detail view of the meltblowing spinneret described in Example 1;

[0033] Figure 3 The end view of the discharge port and the schematic cross-sectional view of the special-shaped holes of the melt-blown spinneret described in Example 1;

[0034] Figure 4 The present invention is a flow chart of the preparation of the melt-blown spinneret;

[0035] Figure 5 A simplified schematic diagram of the selective laser melting 3D printing technology. DETAILED DESCRIPTION

[0036] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0037] Example 1

[0038] An embodiment of the meltblown spinneret of the present invention, the structure of the meltblown spinneret of this embodiment is as follows Figure 1 As shown, the feed port is composed of a conical guide hole and a cylindrical guide hole, and the cylindrical guide hole is connected to the fine spinneret hole at the discharge port end; Figures 2-3 They are respectively the feed port end view and enlarged detail view of the meltblown spinneret described in this embodiment, the discharge port end view and the cross-sectional schematic diagram of the special-shaped hole. In the micro-spinneret holes described in this embodiment, the diameter D1 of the inscribed circle of the special-shaped holes other than the circular holes is equal to the diameter D1 of the circular holes, both of which are 0.2 mm; the diameter D of the cylindrical guide hole is 4 mm, the depth L1 of the guide hole is 4 mm, the depth L2 of the conical guide hole is 2 mm, the depth L3 of the micro-shaped hole is 4 mm, the diameter D3 of the circumference of the micro-shaped hole is half the diameter of the cylindrical guide hole, that is, 2 mm, and the center distance between two adjacent guide holes is the diameter of the cylindrical guide hole plus 4 mm ( Figure 1 The S in the figure is 8mm.

[0039] In this embodiment, a meltblowing spinneret having fine spinneret holes with circular, triangular, regular pentagonal, regular hexagonal and regular octagonal structures is prepared by printing using selective laser melting technology. The specific steps are as follows:

[0040] (1) Prepare the raw powder material to be printed: Use an automatic powder screening device to screen the commercial atomized 316L powder material, and select the powder with a particle size of 15 to 53 μm and an average particle size of 30.65 μm to facilitate powder spreading during the printing process; ball-mill a portion of the screened 316L powder with Al2O3-(10wt.%)ZrO2 powder with a particle size of 60 to 100 nm in a mass ratio of 92:8 to serve as the raw material for the discharge port.

[0041] (2) Oven baking powder: Place the powder in an oven, close the oven door, turn on the oven power, open the exhaust valve, start the vacuum pump to evacuate the oven so that the pressure in the oven is 120 MPa, close the exhaust valve, disconnect the vacuum pump, set the oven temperature to 120°C, and continue for 2 hours. Then, open the exhaust valve. After the exhaust is complete, open the oven door and use heat-insulating gloves to take out the powder.

[0042] (3) Model design and production: Use SolidWorks software to design and model the following Figures 2-3The three-dimensional model of the meltblown spinneret is shown; and the three-dimensional model is imported into the dedicated computer of the printing system, and the Magic supporting software is used to add processing allowance and slice it. The processing allowance is set at the bottom where the three-dimensional model contacts the substrate, with a thickness of 0.2mm and a slice thickness of 0.03mm.

[0043] (4) Addition of powder and setting of printing process parameters: Printing is performed using a selective laser melting 3D printer. Printing here means that the laser selectively melts the powder layer by layer in accordance with the computer-aided design of the three-dimensional model and digital graphic information. In this embodiment, the three-dimensional model of the spinneret designed with the aid of computer SolidWorks software and the digital graphic information obtained after slicing by Magic software are used for printing. The laser melts the powder prepared in step (2) layer by layer in sequence, and a nitrogen atmosphere is used for protection. Before printing begins, the air in the printing chamber is exhausted using the protective gas until the oxygen content is less than 0.1 vol.%. The supply of protective gas is maintained so that the oxygen content is always less than 0.1 vol.%; during printing, the laser power at the discharge port end is set to 160 W; the spot diameter is set to 1 00μm, the scanning speed is set to 1400mm / s, the powder thickness is set to 0.03mm, and the scanning spacing is set to 0.08mm; in addition, in order to reduce the thermal stress between the substrate and the workpiece, the substrate temperature is set and maintained at 100℃; the laser power at the feed port end face is set to 140W; the spot diameter is set to 100μm, the scanning speed is set to 1400mm / s, the powder thickness is 0.03mm, and the scanning spacing is set to 0.08mm; similarly, in order to reduce the thermal stress between the substrate and the workpiece, the substrate temperature is set and maintained at 100℃.

[0044] (5) Workpiece sampling and post-polishing processing: After printing is completed, the remaining unmelted powder is recovered and the powder on the surface of the molded part is removed using a special vacuum cleaner before sampling. The machining excess part of the molded workpiece in contact with the substrate is cut and separated by the electric spark wire cutting method to obtain a spin-molded part with the same size as the involved dimensions; after sampling, the molded part is post-processed, and the abrasive flow polishing process is selected to clean the powder in the micropores and polish the workpiece. Silicon carbide soft abrasive is selected as the polishing abrasive. The fiber optic sensor roughness measuring instrument is used to measure the roughness of the spinneret surface and the inside of the micropores. The average roughness R a Less than 0.4μm.

[0045] Example 2

[0046] An embodiment of the meltblown spinneret of the present invention. The structure and preparation method of the meltblown spinneret in this embodiment are the same as those in Example 1, with the only difference being that, in the raw materials of the discharge port part, the mass proportion of 316L powder and Al2O3-(10wt.%)ZrO2 powder is 15%.

[0047] Comparative Example 1

[0048] A meltblown spinneret, whose structure is the same as that of Example 1, except that the raw materials used for the discharge port and the feed port are both 316L, and the printing parameters of the discharge port part are the same as the printing parameters of the feed port part.

[0049] The performance of the meltblown spinnerets of Examples 1 to 2 and Comparative Example 1 was tested, and the hardness of the spinnerets was measured using a Rockwell hardness tester; a static compression test was performed using a multifunctional material mechanical testing instrument, and a static axial compression test was performed using a constant load. The test results are shown in Table 1.

[0050] Table 1

[0051] project <![CDATA[Hardness (HV 0.2 )]]> Compressive yield strength (MPa) strain Example 1 220-240 180-190 0.07-0.08 Example 2 200-220 170-180 0.06-0.07 Comparative Example 1 190-210 160-170 0.06-0.07

[0052] It can be seen from Table 1 that the meltblown spinneret prepared by the method of the present invention has good mechanical properties and is suitable for application in various fields.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a meltblown spinneret, characterized in that: The steps include: (1) Printing a double-sided heterogeneous integrated structure using a high-energy beam 3D printing process; the high-energy beam 3D printing process includes: electron beam additive manufacturing, laser near-net forming, laser metal forming, and selective laser melting technology; (2) polishing the double-sided heterogeneous integrated structure by abrasive flow polishing technology so that the average roughness Ra of the surface and the interior is less than 0.4 μm, thereby obtaining the meltblown spinneret; The meltblown spinneret has a double-sided heterogeneous integrated structure, one side of which is the end face where the feed port is located, and the other side is the end face where the discharge port is located; the composition of the part where the feed port is located is at least one of 4Cr13, 316L, and SUS304; the composition of the part where the discharge port is located is a mixture of the composition of the part where the feed port is located and ceramic powder; the ceramic powder contains at least one of Al2O3, ZrO2, and TiB2.

2. The method for preparing a meltblown spinneret according to claim 1, wherein: The mass fraction of ceramic powder in the component of the portion where the discharge port is located is 5-10%.

3. The method for preparing a meltblown spinneret according to claim 1, wherein: The feed inlet is provided with a guide hole, and the discharge outlet is provided with a group of fine spinneret holes.

4. The method for preparing a meltblown spinneret according to claim 3, wherein: The guide holes are composed of conical guide holes and cylindrical guide holes from top to bottom, respectively. The cylindrical guide holes are connected to the fine spinneret holes below. The fine spinneret holes include circular holes and at least one non-circular special-shaped hole. The cross-section of the special-shaped hole includes at least one of a triangle, a regular pentagon, a regular hexagon, and a regular octagon.

5. The method for preparing a meltblown spinneret according to claim 4, characterized in that: The inclination of the conical guide hole is 25-35° and the depth is 1.5-2.5 mm; the diameter of the inscribed circle of the special-shaped hole is the same as the diameter of the circular hole, both of which are 0.2-0.3 mm; the fine spinneret holes are distributed on the circumference coaxial with the guide hole, and the diameter of the circle is half the diameter of the cylindrical guide hole.

6. The method for preparing a meltblown spinneret according to claim 5, characterized in that: The depth of the micro-spinning hole is 20 times the diameter of the inscribed circle of the special-shaped hole or the circular hole.

7. The method for preparing a meltblown spinneret according to claim 6, wherein: The diameter of the cylindrical flow guide hole is 20 times the diameter of the inscribed circle of the special-shaped hole or the circular hole; and the center distance between two adjacent cylindrical flow guide holes is the diameter of the cylindrical flow guide hole plus 4 to 5 mm.

8. The method for preparing a meltblown spinneret according to claim 7, wherein: The ratio of the total depth of the conical guide hole and the cylindrical guide hole to the diameter of the cylindrical guide hole is 1:

1.

9. The method for preparing a meltblown spinneret according to claim 1, wherein: In the step (1), the high energy beam 3D printing process is as follows: A. Weigh the raw material powder and sieve it to obtain a powder with a particle size of 15-53 μm; B. Ball milling and mixing the powders required for the discharge port; C. Drying powder; D. Printing with a selective laser melting 3D printer: Use SolidWorks software to build a three-dimensional model, import the three-dimensional model into the printing system, and use Magic software to add processing allowance and slice it; use laser to melt the powder in the parts where the discharge port and the feed port are located in turn. During the printing process, the laser power of the discharge port is 155-165W, the spot diameter is 90-110μm, the scanning speed is 1350-1450mm / s, the powder thickness is 0.025-0.035mm, and the scanning spacing is 0.075-0.085mm; the laser power of the feed port is 135-145W, the spot diameter is 95-105μm, the scanning speed is 1350-1450mm / s, the powder thickness is 0.025-0.035mm, and the scanning spacing is 0.075-0.085mm; the substrate temperature is 90-110℃.

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