Negative pressure drafting melt-blowing spinning device

Abstract

The invention relates to the technical field of non-woven material manufacturing equipment, in particular to a negative pressure drafting melt-blowing spinning device which comprises a box body, a screen, a melt heating mechanism, a receiving mechanism and a negative pressure mechanism. A micro-channel and a negative pressure channel are formed in the box body; the screen is used for receiving and transferring the molten polymer; the melt heating mechanism is arranged towards the screen; the receiving mechanism is used for receiving fibers; and a negative pressure channel is communicated with the box body, a negative pressure environment is provided for the interior of the box body, and the molten polymer is drafted through the micro-channel. A negative pressure environment is formed in the box body through the negative pressure mechanism, local negative pressure is provided below the screen through the slits formed in the inner sides of the micro-channels, and under the gravity and negative pressure conditions, drafting of molten polymers is achieved, and melt is drafted through the negative pressure, so that the recoil effect of the screen on positive pressure airflow in the prior art is reduced, and the drafting effect is improved. Meanwhile, negative pressure can be used as main drafting force, and stable and continuous preparation of the micro-nano fibers is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of non-woven material manufacturing equipment, and particularly to a meltblown spinning device with negative pressure drawing. Background Art

[0002] The meltblowing method is an industrial method for obtaining micro-nano fiber materials by stretching the polymer melt extruded from a spinneret with a high-temperature and high-speed air flow, and is widely used in fields such as air filtration, medical materials, sound absorption and noise reduction. At present, the stretching of the polymer melt during meltblowing spinning all adopts the positive pressure air flow stretching technology. The melt is stretched forward by a high-speed air flow to form ultrafine fibers, which has the advantages of short process and high production efficiency in the production of non-woven fabrics. However, the stretching process involves high-temperature and high-speed air flow, the air flow speed is as high as 260 m / s, and the required air pressure is as high as 0.2 Mpa, resulting in high energy consumption, and accompanied by relatively large noise generated by the high-speed air flow; at the same time, the high-temperature and high-speed air flow has a greater impact on other accessories such as the spinneret, resulting in greater wear of the high-precision spinneret, and often requires polishing or even replacement.

[0003] In the prior art, a screen is mostly used to achieve meltblown spinning without spinneret holes. The screen woven by metal wires has a certain backwashing effect on the positive pressure air flow. On the one hand, it causes part of the melt to form thick fibers in the direction of the air flow backwashing, resulting in the phenomenon of floating filaments in the air; on the other hand, it also causes part of the air flow loss and the jet stretching speed to decrease. The above two problems will both lead to low meltblown spinning efficiency. Summary of the Invention

[0004] The present invention provides a meltblown spinning device with negative pressure drawing to solve the defects in the prior art that in the meltblown spinning without spinneret holes using positive pressure air flow, part of the melt forms thick fibers in the direction of the air flow backwashing, resulting in the phenomenon of floating filaments in the air, and part of the air flow loss and the jet stretching speed decrease.

[0005] The present invention provides a meltblown spinning device with negative pressure drawing, including: A box body, on which a micro-channel and a negative pressure channel are formed; A screen, disposed outside the box body and covering the micro-channel, for receiving and transferring the molten polymer; A melt heating mechanism, disposed outside the box body and facing the screen; A receiving mechanism, movably passing through the box body, and at least part of the receiving mechanism is located below the micro-channel, for receiving fibers; A negative pressure mechanism, communicating with the box body through the negative pressure channel, providing a negative pressure environment inside the box body, and the micro-channel is used to accelerate the air flow speed and generate a negative pressure turbulent field to stretch the molten polymer.

[0006] According to the meltblown spinning device with negative pressure drawing provided by the present invention, the shape of the microchannel is any one of a cuboid, a single frustum, and a double frustum; Among them, the double frustum is formed by symmetrically combining two single frustums.

[0007] According to the meltblown spinning device with negative pressure drawing provided by the present invention, it further includes: A first driving mechanism, connected to the receiving mechanism, for driving the receiving mechanism to move so as to transfer the received fibers from the inner side of the box to the outer side of the box.

[0008] According to the meltblown spinning device with negative pressure drawing provided by the present invention, it further includes: A sliding support mechanism, movably arranged inside the box, located between the negative pressure channel and the receiving mechanism and supporting the receiving mechanism. The sliding support mechanism has a plurality of through holes for the negative pressure air flow of the negative pressure mechanism to pass through, and intercepts the fibers falling from the receiving mechanism to prevent the fibers from entering the negative pressure channel.

[0009] According to the meltblown spinning device with negative pressure drawing provided by the present invention, the negative pressure channel is arranged on the wall of the box away from the microchannel, and the receiving mechanism and the sliding support mechanism are sequentially arranged between the microchannel and the negative pressure channel.

[0010] According to the meltblown spinning device with negative pressure drawing provided by the present invention, it further includes: An extrusion mechanism, arranged on the screen and located upstream of the melt heating mechanism. The extrusion mechanism is used to heat and melt the polymer resin, form molten polymer and extrude it onto the screen; The screen can transfer the molten polymer extruded by the extrusion mechanism to the lower part of the melt heating mechanism.

[0011] According to the meltblown spinning device with negative pressure drawing provided by the present invention, the screen includes any one of a sliding screen, a rotary disk screen, and a rotary drum screen.

[0012] According to the meltblown spinning device with negative pressure drawing provided by the present invention, the heating temperature of the melt heating mechanism ranges from 270 to 335 °C; the vertical distance between the melt heating mechanism and the screen ranges from 5 to 20 mm.

[0013] According to the meltblown spinning device with negative pressure drawing provided by the present invention, the minimum width of the caliber of the microchannel ranges from 1 to 15 mm, the height of the microchannel ranges from 10 to 60 mm, and the vertical distance between the inlet of the microchannel and the screen ranges from 10 to 30 mm.

[0014] According to the meltblown spinning device with negative pressure drawing provided by the present invention, the pressure provided by the negative pressure mechanism ranges from 40 to 80 Kpa, and the air volume ranges from 420 to 1300 m 3 / h.

[0015] A meltblown spinning device with negative pressure drawing provided by the present invention includes: a box body, a screen, a melt heating mechanism, a receiving mechanism, and a negative pressure mechanism. A microchannel and a negative pressure channel are formed on the box body; the screen is arranged outside the box body and above the microchannel for receiving and transferring the molten polymer; the melt heating mechanism is arranged outside the box body and above the screen and faces the screen; the receiving mechanism movably penetrates the box body, and at least part of the receiving mechanism is located below the microchannel for receiving fibers; it is communicated with the box body through the negative pressure channel to provide a negative pressure environment inside the box body, and the microchannel is used to accelerate the air flow velocity and generate a negative pressure turbulent field to draw the molten polymer. In the meltblown spinning device with negative pressure drawing provided by the present invention, the negative pressure mechanism forms a negative pressure environment in the box body through the negative pressure channel, and provides local negative pressure below the screen through the slit formed inside the microchannel. Under its gravity and negative pressure conditions, the stretching of the molten polymer is realized, and the melt is stretched by negative pressure to reduce the recoil effect of the screen on the positive pressure air flow in the prior art, reduce energy consumption, and at the same time, the negative pressure can be used as the main stretching force to realize the stable and continuous preparation of micro-nano fibers. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 is a schematic structural diagram of the meltblown spinning device with negative pressure drawing provided in Embodiment 1 of the present invention.

[0018] Figure 2 is a front view of the meltblown spinning device with negative pressure drawing provided in Embodiment 1 of the present invention.

[0019] Figure 3 is a top view of the meltblown spinning device with negative pressure drawing provided in Embodiment 1 of the present invention.

[0020] Figure 4 is a schematic structural diagram of the microchannel provided in Embodiment 1 of the present invention.

[0021] Figure 5 is a schematic structural diagram of the microchannel with a single frustum structure in one of the embodiments of the present invention.

[0022] Figure 6 It is a schematic structural diagram of a microchannel adopting a single frustum structure in one embodiment of the present invention.

[0023] Figure 7 It is a schematic structural diagram of a microchannel adopting a double frustum structure in one embodiment of the present invention.

[0024] Figure 8 It is a PLA fiber morphology diagram of the fiber prepared in Example 1 of the present invention.

[0025] Figure 9 It is a PLA fiber morphology diagram of the fiber prepared in Example 2 of the present invention.

[0026] Reference numerals: 1. Box body; 101: Microchannel; 102: Negative pressure channel; 103: Visualization window; 2. Screen; 3. Melt heating mechanism; 4. Receiving mechanism; 51. Winding drum; 52. Unwinding drum; 6. Sliding support mechanism; 7. Second driving mechanism. Detailed implementation manners

[0027] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts fall within the protection scope of the present invention.

[0028] In the description of this embodiment, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this embodiment and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to this embodiment.

[0029] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of this embodiment, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0030] In this embodiment, unless otherwise clearly defined or limited, terms such as "arranged", "installed", "connected", "joined", "fixed", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in this embodiment can be understood according to specific circumstances.

[0031] In the embodiments of the present invention, unless otherwise clearly defined or limited, the first feature being "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature can be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature can be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0032] The following will be combined with Figures 1 - 9 to describe a meltblown spinning device with negative pressure drawing of the present invention. The meltblown spinning device with negative pressure drawing includes: a box body 1, a screen 2, a melt heating mechanism 3, a receiving mechanism 4 and a negative pressure mechanism.

[0033] Among them, a microchannel 101 and a negative pressure channel ********** are formed on the box body 1; the screen 2 is arranged outside the box body 1 and covers the microchannel 101 for receiving and transferring the molten polymer; the melt heating mechanism 3 is arranged outside the box body 1 and is oriented towards the screen 2; the receiving mechanism 4 movably penetrates through the box body 1, and at least part of the receiving mechanism 4 is located below the microchannel 101 for receiving fibers; it is connected to the box body 1 through the negative pressure channel ********** to provide a negative pressure environment inside the box body 1, and the microchannel 101 is used to accelerate the air flow speed and generate a negative pressure turbulent field to draw the molten polymer.

[0034] Specifically, the screen 2 is located above the microchannel, and the melt heating mechanism 3 is located above the microchannel.

[0035] It should be noted that there is an unclear part in the original text where "**********" appears in the description of the negative pressure channel in line 12. This part has been translated as "**********" in the English version to maintain the integrity of the original text. If the specific content of this part can be determined, a more accurate translation can be provided.Specifically, the box body 1 is a negative pressure box body made of high-temperature resistant stainless steel, which has a certain ability to withstand negative pressure and ensures the sealing inside the box body 1. Two channels are formed on the box body 1, one is the micro-channel 101 and the other is the negative pressure channel 102. Both channels are through channels connecting the inner side and the outer side of the box body 1. The box body 1 is only connected to the outside at the micro-channel 101 and the negative pressure channel 102, and other positions of the box body 1 are closed during the spinning process. Therefore, the box body 1 is a semi-open box body. The negative pressure channel 102 can achieve a negative pressure environment inside the box body 1 through the negative pressure provided by the negative pressure mechanism, and through the micro-channel 101 provided on the box body 1, the molten polymer is drawn by the negative pressure air flow.

[0036] Specifically, the negative pressure mechanism forms a negative pressure environment inside the box body 1 through the negative pressure channel 102; through the slit (i.e., narrow gap) formed inside the micro-channel 101, when the air flow passes through the slit, according to the principle of mass conservation and Bernoulli's principle, the air flow velocity inside the slit will increase, and the air flow pressure below the screen 2 will decrease, generating a local negative pressure area, causing a large velocity gradient above the slit, resulting in the external air flow being sucked in. Under the conditions of its gravity and suction, the melt realizes the drawing of the molten polymer. On the other hand, the slit formed inside the micro-channel 101 guides the flow of the molten polymer and the direction of the air flow, forming a directional drawing of the air flow on the melt. The "micro" in the micro-channel 101 means that the size of its channel is smaller compared to the size of the box body 1. The air flow passes through a movement path that first contracts (the caliber of the micro-channel is smaller) and then expands (the volume of the box body is larger). When the negative pressure air flow passes through the suddenly reduced caliber of the micro-channel 101, streamline contraction will occur, generating eddy currents or streamline bending. Due to the characteristics of its rotational flow, the eddy current can cause disturbances in local areas of the fluid, and these disturbances will affect the morphological changes of the fiber during the drawing process. Through the disturbing effect of the flow of the eddy current, the stress distribution on the fiber during the stretching process is more uniform, thereby avoiding excessive or uneven local stress and ensuring that the fiber refinement process is more uniform and stable. At the same time, through the negative pressure turbulent flow field, the interaction between the melt jet and the air flow is increased. The eddy current may cause the rotational flow of the fiber, thereby leading to changes in the fiber morphology, and its morphological changes depend on the intensity of the turbulence. Through the partial orientation of the negative pressure air flow area, on the one hand, the air flow velocity speeds up the drawing of the melt, obtaining fibers with a finer diameter, and on the other hand, the air flow morphology will affect the obtained fiber morphology. In the present invention, since the negative pressure air flow is used to directionally draw the melt, a local negative pressure is formed on one side of the screen 2, and no reverse air flow will be generated, and therefore no thick fibers will be generated in the reverse direction of the reverse air flow, resulting in the phenomenon of floating filaments, and the air flow loss is reduced, and the jet drawing speed and fiber output are improved.

[0037] The screen 2 has an array of through-holes, which on the one hand enables the molten polymer to be evenly laid, and on the other hand enables the molten polymer to fall from the upper surface of the screen 2 through the through-holes into the micro-channel 101 and enter the inside of the box 1 from the micro-channel 101. Moreover, the external air flow can enter the negative pressure micro-channel through the through-holes of the screen 2, further improving the melt stretching efficiency.

[0038] The melt heating mechanism 3 is located above the micro-channel 101 and is used to further heat the molten polymer on the screen 2 to a specified temperature to ensure its flow state. Under the influence of gravity and negative pressure, the polymer melt sequentially passes through the through-holes of the screen 2 and the micro-channel 101 and enters the inside of the box 1. The melt heating mechanism 3 can adopt devices such as a hot air gun or a laser heater, or can also adopt the methods of indirect heating with hot air or indirect heating with infrared radiation.

[0039] A part of the receiving mechanism 4 is located inside the box 1 and is used to receive the formed fibers, and the received fibers are removed from the box 1 by the movement of the receiving mechanism 4. The receiving mechanism 4 preferably adopts non-woven fabric, which has excellent air permeability, is convenient for air flow to pass through, and is also easy to peel off the formed fibers.

[0040] The negative pressure mechanism provides support for the negative pressure environment inside the box 1, and it can adopt structures such as a negative pressure vortex blower or a vacuum pump.

[0041] A meltblown spinning device with negative pressure stretching provided by the present invention includes: a box 1, a screen 2, a melt heating mechanism 3, a receiving mechanism 4 and a negative pressure mechanism. A micro-channel 101 and a negative pressure channel 102 are formed on the box 1; the screen 2 is arranged outside the box 1 and is located above the micro-channel 101 and is used to receive and transfer the molten polymer; the melt heating mechanism 3 is arranged outside the box 1 and is located above the screen 2 and is arranged towards the screen 2; the receiving mechanism 4 movably penetrates through the box 1, and at least a part of the receiving mechanism 4 is located below the micro-channel 101 and is used to receive fibers; it is communicated with the box 1 through the negative pressure channel 102 to provide a negative pressure environment inside the box 1, and the micro-channel 101 is used to accelerate the air flow speed and generate a negative pressure turbulent field to stretch the molten polymer. A meltblown spinning device with negative pressure stretching provided by the present invention, the negative pressure mechanism forms a negative pressure environment inside the box 1 through the negative pressure channel 102, and provides local negative pressure below the screen 2 through the slit formed inside the micro-channel 101. Under the conditions of its gravity and negative pressure, the stretching of the molten polymer is realized, and the melt is stretched by negative pressure to reduce the backwashing effect of the screen 2 on the positive pressure air flow in the prior art, reduce energy consumption, and at the same time the negative pressure can be used as the main stretching force to realize the stable and continuous preparation of micro-nano fibers.

[0042] In one embodiment of the present invention, the shape of the micro-channel 101 is any one of a cuboid, a single frustum and a double frustum. Among them, the double frustum is formed by symmetrically combining two single frustums.

[0043] As shown Figure 4 in FIG. 1, the microchannel 101 adopts a cuboid structure. Preferably, the dimensions of the microchannel 101 are as follows: the length is 70 mm, the width is 10 mm, and the height is 50 mm.

[0044] As shown Figure 5 and 6 in FIGS. 2 and 3, the microchannel 101 adopts a single frustum structure, which has two implementation manners: one is that the caliber of the single frustum gradually expands from small to large in the direction of the negative pressure air flow, and it is a frustum of a quadrangular pyramid with a wider upper part and a narrower lower part, that is, the structure shown in Figure 5 FIG. 4. Preferably, the height of the single frustum is 50 mm, and both its melt inlet and melt outlet are rectangular. The length and width of the melt inlet are 100 mm and 20 mm respectively, and the length and width of the melt outlet are 50 mm and 10 mm respectively; the other is that the caliber of the single frustum gradually shrinks from large to small in the direction of the negative pressure air flow, and it is a frustum of a quadrangular pyramid with a narrower upper part and a wider lower part, that is, the structure shown in Figure 6 FIG. 5. Preferably, the height of the single frustum is 50 mm, and both its melt inlet and melt outlet are rectangular. The length and width of the melt inlet are 70 mm and 15 mm respectively, and the length and width of the melt outlet are 140 mm and 30 mm respectively.

[0045] As shown Figure 7 in FIG. 6, the microchannel 101 adopts a double frustum structure, which adopts a combined form of symmetric single frustum structures. The caliber of the double frustum forms a structure of first shrinking and then expanding in the direction of the negative pressure air flow, that is, the structure shown in Figure 7 FIG. 7. The air flow enters the contraction section of the microchannel 101 at a low speed. Since the shape of the microchannel 101 gradually becomes narrower, the flow rate of the gas gradually increases and the pressure gradually decreases. Then the microchannel gradually expands. Due to the decrease in pressure, the speed of the air flow continues to increase and even reaches subsonic speed, and effective refinement of the melt jet can be achieved. The height of the double frustum is 60 mm, and both the melt inlet and melt outlet are rectangular, with the length and width being 70 mm and 45 mm respectively, and the length and width of the middle contraction opening are 15.5 mm and 10 mm respectively.

[0046] In one embodiment of the present invention, the meltblown spinning device with negative pressure drawing further includes: a first driving mechanism, which is connected to the receiving mechanism 4 and is used to drive the receiving mechanism 4 to move so as to transfer the received fibers from the inside of the box body 1 to the outside of the box body 1. Preferably, the first driving mechanism includes: a winding drum 51 and an unwinding drum 52. The winding drum 51 is connected to one end of the receiving mechanism 4; the unwinding drum 52 is connected to the other end of the receiving mechanism 4, and the other end is the opposite end of the receiving mechanism 4 connected to the winding drum 51.

[0047] In the above embodiment, the first driving mechanism adopts a drum driving method. The winding drum 51 provides the winding power, and the unwinding drum 52 provides the unwinding power. Through the coordinated driving of the winding drum 51 and the unwinding drum 52, the receiving mechanism 4 is moved, and the fibers thereon are transported out of the box body 1. It should be understood that the first driving mechanism can also adopt other power devices, such as motors and the like.

[0048] In one embodiment of the present invention, the meltblown spinning device with negative pressure drawing further includes: a sliding support mechanism 6, which is movably arranged in the box body 1, located between the negative pressure channel 102 and the receiving mechanism 4 and supported on the receiving mechanism 4. The sliding support mechanism 6 has a plurality of through holes for the negative pressure air flow of the negative pressure mechanism to pass through, and intercepts the fibers falling from the receiving mechanism 4 to prevent the fibers from entering the negative pressure channel 102.

[0049] Preferably, the sliding support mechanism 6 adopts a flat receiving mesh curtain with a through hole structure, or a drum collector, etc.

[0050] In the above embodiment, the sliding support mechanism 6 has the following two effects: 1. Since the receiving mechanism 4 needs to transfer the fibers out of the box body 1, on the one hand, the sliding support mechanism 6 provides a supporting effect on the receiving mechanism 4, and on the other hand, it also provides a movement at the same moving speed as the receiving mechanism 4 to ensure that it runs at the same speed as the sieve mesh 2 and avoid the frictional loss caused by the relative movement between the two.

[0051] 2. Since the sliding support mechanism 6 is formed with a plurality of through holes, on the one hand, it can allow the negative pressure air flow to pass through, and on the other hand, since there may be falling fibers in the receiving structure, the falling fibers are intercepted by the solid structure around the through holes to avoid the problem of blockage of the negative pressure channel 102 caused by the fibers entering the negative pressure channel 102.

[0052] In one embodiment of the present invention, the meltblown spinning device with negative pressure drawing further includes: a second driving mechanism 7, which is connected to the sliding support mechanism 6 and is used to drive the sliding support mechanism 6 and the receiving mechanism 4 to move synchronously.

[0053] In the above embodiment, the second driving mechanism 7 can adopt a motor or a drum structure to drive the sliding support mechanism 6. The fixed end of the second driving mechanism 7 is supported on the bottom wall of the box body 1 and raises the sliding support mechanism 6 so that there is a height difference between it and the negative pressure channel 102.

[0054] In one embodiment of the present invention, the negative pressure channel 102 is arranged on the wall surface of the box body 1 far from the microchannel 101, and the receiving mechanism 4 and the sliding support mechanism 6 are sequentially arranged between the microchannel 101 and the negative pressure channel 102.

[0055] In the above embodiments, the negative pressure channel 102 and the microchannel 101 are respectively located on two opposite walls of the box body 1. Preferably, the negative pressure channel 102 is located on the bottom wall of the box body 1, and the microchannel 101 is located on the top wall of the box body 1. Inside the box body 1, a receiving mechanism 4 and a sliding support mechanism 6 are sequentially arranged between the top wall and the bottom wall.

[0056] In one embodiment of the present invention, the distance between the sliding support mechanism 6 and the negative pressure channel 102 ranges from 10 to 25 cm. By setting the gap between the sliding support mechanism 6 and the negative pressure channel 102, the influence of the sliding support mechanism 6 on the negative pressure air flow is avoided.

[0057] In one embodiment of the present invention, the melt-blowing spinning device with negative pressure drawing further includes: an extrusion mechanism, which is arranged on the screen 2 and is located upstream of the melt heating mechanism 3. The extrusion mechanism is used to heat and melt the polymer resin to form molten polymer and extrude it onto the screen 2. The screen 2 can transfer the molten polymer extruded by the extrusion mechanism to the lower part of the melt heating mechanism 3.

[0058] In the above embodiments, by arranging an extrusion mechanism upstream of the screen 2, it is used to extrude the molten polymer onto the screen 2. Preferably, the extrusion mechanism can adopt a screw extruder (with four temperature zones, and the temperatures of each zone are 50°C, 190°C, 230°C, and 250°C respectively). The screen 2 is movably arranged above the box body 1. Through the movement of the screen 2, the molten polymer is transferred to the lower part of the melt heating mechanism 3, and the melt heating mechanism 3 further heats the molten polymer.

[0059] In one embodiment of the present invention, the screen 2 includes any one of a sliding screen, a rotary disk screen, and a rotary drum screen. Specifically, the sliding screen can transfer the molten polymer to the lower part of the melt heating mechanism 3 through its sliding; the rotary disk screen and the rotary drum screen transfer the molten polymer to the lower part of the melt heating mechanism 3 through their rotation.

[0060] In one embodiment of the present invention, the melt-blowing spinning device with negative pressure drawing further includes: a visualization window 103, which is arranged on the side wall of the box body 1. Specifically, the formation of fibers inside the box body 1 can be observed through the visualization window 103.

[0061] In one embodiment of the present invention, the heating temperature of the melt heating mechanism 3 ranges from 270 to 335°C; the vertical distance between the melt heating mechanism 3 and the screen 2 ranges from 5 to 20 mm.

[0062] In one embodiment of the present invention, the minimum width of the caliber of the microchannel 101 ranges from 1 to 15 mm, the height of the microchannel 101 ranges from 10 to 60 mm, and the vertical distance between the inlet of the microchannel 101 and the screen 2 ranges from 10 to 30 mm.

[0063] In one embodiment of the present invention, the pressure provided by the negative pressure mechanism ranges from 40 to 80 Kpa, and the air volume ranges from 420 to 1300 m 3 / h.

[0064] The present invention provides the following two embodiments.

[0065] Embodiment 1: The structure of the meltblown spinning device with negative pressure drawing in this embodiment is as Figure 1 and Figure 4 shown.

[0066] Among them, the screw extruder is used to heat and melt the polymer resin and extrude it to form a polymer melt; the screen 2 serves as a melt carrier and moves horizontally at a preset moving speed of 5 cm / s; the hot air gun is arranged above the mobile screen 2, and the direction of its hot air flow is parallel to the direction of the negative pressure air flow, and the vertical distance from the screen 2 is 5 mm; the negative pressure box body 1 made of high-temperature resistant stainless steel is provided with a microchannel 101 at its top, which is a cuboid structure with a length, width and height of 70 mm, 10 mm and 50 mm respectively. A negative pressure environment of 60 KPa is maintained in the box body 1, and the air volume is 1100 m 3 / h (the structures of the microchannel 101 and the screen 2 are as Figure 4 shown); the receiving mesh curtain is arranged directly below the screen 2, above the negative pressure channel 102, and is 15 cm away from it. The surface of the receiving mesh curtain is covered with pores for passing the negative pressure air flow. There is a non-woven fabric above the receiving mesh curtain for receiving the formed fibers. Preferably, the non-woven fabric is connected to the winding roller 51 and the unwinding roller 52. The rotation of the winding roller 51 drives the non-woven fabric to move from the unwinding roller 52, and the fiber film or fiber felt deposited on the non-woven fabric is removed in time. Specifically, when the polylactic acid polymer melt is extruded by the screw extruder (the temperatures of each zone are 50°C, 190°C, 230°C, 250°C) and then evenly loaded on the surface of the screen 2 through the melt transfer device (its heating temperature is 265°C), when the screen 2 is transported to the melt heating area, a hot air gun with a power of 450 W is used to locally irradiate and heat the melt, and the heating temperature is 270°C, so that the melt is instantaneously heated to a low viscosity state; under the action of the negative pressure air flow, the melt is stretched to form polylactic acid ultrafine fibers with an average diameter of 600 - 2000 nm, and is finally received by the non-woven fabric above the receiving mesh curtain. The moving speed of the receiving mesh curtain is 1 cm / s, and the fiber is formed into a non-woven fabric felt (as Figure 8As shown, it is the PLA fiber morphology diagram of the fibers prepared by the device of this embodiment).

[0067] Example 2: This example only illustrates the differences from Example 1: A laser radiation unit is used instead of the hot air gun. It is arranged above the screen 2, and its laser emission direction is perpendicular to the melt conveying direction and parallel to the negative pressure air flow direction; a microchannel 101 with a symmetric quadrangular pyramid structure is provided at the top of the box body 1, forming a structure that first contracts and then expands (its structure is as Figure 7 shown). Both the melt inlet and the melt outlet are rectangular, with a length and width of 70 mm and 45 mm respectively, the length and width of the middle contraction port are 15.5 mm and 10 mm respectively, the height of the microchannel 101 is 60 mm, a negative pressure environment of 50 KPa is maintained inside the box body 1, and the air volume is 1150 m 3 / h; the rotary drum screen is arranged directly below the screen 2, above the negative pressure channel 102, and is 15 cm away from it, for collecting the formed fibers, and the rotation speed of the drum is set to 6 rpm. Specifically, when the polylactic acid polymer melt is extruded by a screw extruder (the temperatures of each zone are 50°C, 190°C, 230°C, 250°C) and then evenly loaded on the surface of the screen 2 (40 mesh) through a melt transfer module (its heating temperature is 265°C), when the screen 2 is transported to the melt heating area, a carbon dioxide laser with a power of 4 W is used to locally irradiate and heat the melt, so that the melt instantaneously rises to a low viscosity state; under the action of the negative pressure air flow, the melt is stretched to form polylactic acid nanofibers with an average diameter of 400 - 900 nm, and finally formed into a non-woven fabric felt by a drum collector (as Figure 9 shown, it is the PLA fiber morphology diagram of the fibers prepared by the device of this embodiment). Through the synergistic effect of optimizing the laser radiation parameters and the negative pressure air flow conditions in this example, the efficient preparation of polylactic acid ultrafine fibers is realized.

[0068] The device embodiments described above are merely illustrative. The units described as separation components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative labor.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A meltblown spinning device with negative pressure drawing, characterized in that, Comprising: A box body (1) on which a micro-channel (101) and a negative pressure channel (102) are formed; A screen mesh (2) provided outside the box body (1) and covering the micro-channel (101) for receiving and transferring molten polymer; A melt heating mechanism (3) provided outside the box body (1) and facing the screen mesh (2); A receiving mechanism (4) movably penetrating through the box body (1), and at least part of the receiving mechanism (4) is located below the micro-channel (101) for receiving fibers; A negative pressure mechanism communicated with the box body (1) through the negative pressure channel (102) to provide a negative pressure environment inside the box body (1). The micro-channel (101) is used to accelerate the air flow velocity and generate a negative pressure turbulent field to draw the molten polymer.

2. The meltblown spinning device with negative pressure drafting according to claim 1, characterized in that, The shape of the micro-channel (101) is any one of a cuboid, a single frustum and a double frustum; Wherein, the double frustum is formed by symmetrically combining two single frustums.

3. The meltblown spinning device with negative pressure drafting according to claim 1, characterized in that Further comprising: A first driving mechanism connected to the receiving mechanism (4) for driving the receiving mechanism (4) to move so as to transfer the received fibers from the inside of the box body (1) to the outside of the box body (1).

4. The meltblown spinning device with negative pressure drafting according to claim 1, characterized in that, Further comprising: A sliding support mechanism (6) movably provided inside the box body (1), located between the negative pressure channel (102) and the receiving mechanism (4) and supporting the receiving mechanism (4). The sliding support mechanism (6) has a plurality of through holes for the negative pressure air flow of the negative pressure mechanism to pass through and intercept the fibers falling from the receiving mechanism (4) to prevent the fibers from entering the negative pressure channel (102).

5. The meltblown spinning device with negative pressure drafting according to claim 4, characterized in that, The negative pressure channel (102) is provided on the wall surface of the box body (1) away from the micro-channel (101), and the receiving mechanism (4) and the sliding support mechanism (6) are sequentially provided between the micro-channel (101) and the negative pressure channel (102).

6. The negative pressure drafted melt-blown spinning device according to claim 1, characterized in that: Further comprising: An extrusion mechanism provided on the screen mesh (2) and located upstream of the melt heating mechanism (3). The extrusion mechanism is used to heat and melt the polymer resin to form molten polymer and extrude it onto the screen mesh (2); The screen mesh (2) can transfer the molten polymer extruded by the extrusion mechanism to below the melt heating mechanism (3).

7. The meltblown spinning device with negative pressure drawing according to any one of claims 1 to 6, characterized in that The screen mesh (2) includes any one of a sliding screen mesh, a rotary disk screen mesh and a rotary drum screen mesh.

8. The meltblown spinning device with negative pressure drafting according to any one of claims 1 to 6, characterized in that, The heating temperature of the melt heating mechanism (3) ranges from 270 to 335 °C; the vertical distance between the melt heating mechanism (3) and the screen mesh (2) ranges from 5 to 20 mm.

9. The meltblown spinning device with negative pressure drafting according to any one of claims 1 to 6, characterized in that, The minimum width of the caliber of the micro-channel (101) ranges from 1 to 15 mm, the height of the micro-channel (101) ranges from 10 to 60 mm, and the vertical distance between the inlet of the micro-channel (101) and the screen mesh (2) ranges from 10 to 30 mm.

10. The meltblown spinning device with negative pressure drafting according to any one of claims 1 to 6, characterized in that, The pressure value range provided by the negative pressure mechanism is 40 - 80 Kpa, and the air volume value range is 420 - 1300 m 3 / h.

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