Preparation process and system of superfine fiber non-woven fabric based on regenerated cellulose

Abstract

The invention discloses a preparation process and system of superfine fiber non-woven fabric based on regenerated cellulose, and belongs to the technical field of non-woven fabric production. On one hand, the invention provides a preparation process which comprises the working procedures of filtering, spinning, blowing, spraying, spunlacing, drying and the like, and solves the problems that in the preparation process of the superfine fiber non-woven fabric, the fiber bonding degree is high, films are formed in more areas, the number of monofilaments in the non-woven fabric is small, and part of monofilaments are embedded in the films, so that the non-woven fabric is difficult to deform. Part of monofilaments are highly crossed and bridged among the films; on the other hand, an adaptive preparation system is provided, and orderliness, controllability and stability of the preparation process are guaranteed; finally, the melt-blown non-woven fabric of the superfine fibers is obtained, and in the obtained melt-blown non-woven fabric of the superfine fibers, the fibers are fine and soft, the diameters of the fibers are uniform, and diameter distribution is concentrated.

Description

Technical Field

[0001] The invention relates to a nonwoven fabric preparation process and system, and in particular to a nonwoven fabric preparation process and system based on regenerated cellulose ultrafine fiber, belonging to the technical field of nonwoven fabric production. Background Art

[0002] Meltblown is a nonwoven fabric technology that heats and pressurizes polymers into a molten state, and then extrude them into a web through a spinneret and a nozzle. Since the fiber diameter produced by meltblown nonwoven fabric technology is 1 to 10 μm, it shows the advantages of ultra-fine fibers, making meltblown nonwoven fabrics widely used in civil and industrial fields. With the development of technology in various fields and the enhancement of people's environmental awareness, meltblown nonwoven fabric technology has also developed rapidly in recent years. In terms of the development of new raw materials, efforts are being made to study meltblown nonwoven fabric technology using cellulose solution as raw material.

[0003] At present, regenerated cellulose ultrafine fiber non-woven fabrics are prepared based on the melt-blown method using cellulose solution as raw material. Generally, the nascent fiber web is first collected on a dry and clean drum, and then the nascent fiber web is washed through a water washing process to wash away excess solvent in the fibers and regenerate the fibers. The fibers obtained by this method have high adhesion, and more areas form thin films, resulting in a smaller number of monofilaments in the product non-woven fabric, some monofilaments are embedded in the thin films, and some monofilaments are highly cross-bridged between the films.

[0004] Prior art CN109487435A discloses "a kind of ultrafine fiber mesh non-woven fabric", wherein PET and PA6 two-component orange-peel composite filament fibers are prepared by spunbonding method; CN102926135A discloses "a kind of biodegradable composite ultrafine fiber non-woven fabric and its preparation method", wherein the specific materials are polylactic acid ultrafine fibers and poly-ε-caprolactone ultrafine fibers, and the problem of performance degradation in use caused by phase separation is avoided; CN117026520A discloses "a method for manufacturing ultrafine fiber long fiber non-woven fabric", wherein polypropylene, polyester, PET, PA6, etc. are used as raw materials, and the raw materials are directly extruded by spinning after hot melting, and the raw materials are stretched, elongated and thinned by high-speed wind during the spinning extrusion process through the action of a traction device to form fine fibers, but the melt spinning method is adopted, and the fiber diameter formed is generally 16-20μm, that is, the fiber diameter is relatively large; at the same time, the prior art is for conjugated synthetic polymer artificial filaments, and the prepared non-woven fabric does not have the advantages of environmental protection and degradability. Summary of the invention

[0005] In order to solve the problems that the fiber bonding degree of the ultrafine fiber non-woven fabric prepared in the prior art is high, a large number of regions form thin films, the number of monofilaments in the non-woven fabric is small, and some monofilaments are embedded in the thin films and some monofilaments are highly cross-bridged between the thin films, a preparation process and system of ultrafine fiber non-woven fabric based on regenerated cellulose is proposed, which ensures that 97-99% of the solvent (N-methylmorpholine-N-oxide, NMMO) is removed instantly when the dissolving pulp is ejected from the spinneret hole, the thin flow of the dissolving pulp is more easily deformed under the action of the airflow, and the entanglement degree between the fibers (film bonding) is reduced. Therefore, after regeneration (destroying the solvent dissolution stability, the fibers are gradually precipitated from the solvent), the final form of the fibers is maintained, that is, the fiber diameter is 2-7.5µm, and the fiber diameter is concentrated in 3.5-6.5µm (accounting for 80-88%). In addition, the remaining solvent (1-3%) is removed in time through the lateral cold air and water washing process, maintaining the final shape of the regenerated fiber, that is, ensuring the preparation of melt-blown non-woven fabrics with concentrated fiber diameter and uniform appearance.

[0006] In order to achieve the above technical objectives, the following technical solutions are proposed: The first purpose of the technical solution is to provide: a preparation process of ultrafine fiber nonwoven fabric based on regenerated cellulose, comprising: S1 filtration: the cellulose dissolving pulp is passed through a twin-screw extruder into a filter device with a filter mesh diameter of 0.04-0.06 mm, and filtered to obtain a filtered cellulose dissolving pulp; Among them, a twin-screw extruder is used to further dissolve and disperse the dissolving slurry, so as to further eliminate the bubbles in the dissolving slurry and further dissolve the undissolved impurities, which is beneficial to the stability of subsequent spinning and the improvement of the quality of the final filaments. And the temperature in the twin-screw extruder is controlled: the temperature of zone one is 95-98°C, the temperature of zone two is 95-98°C, the temperature of zone three is 95-98°C, and the temperature of zone four is 95-98°C. Further limitation of the temperature of each zone ensures that the twin screw homogenizes the dissolving slurry and performs a double dissolution of the undissolved rubber blocks by the twin screw, that is, the shear force of the screw machine is used to break the rubber blocks and dissolve them again. At the same time, the undissolved impurities are dissolved again to improve the dissolution uniformity of the dissolving slurry and effectively reduce the influence of impurities on the subsequent spinning stability. In addition, the temperature of the four zones can be controlled to be consistent, which effectively improves the dissolution uniformity of the dissolving slurry. The zoning setting ensures the independent adjustability of the temperature of each zone. The indicators of cellulose dissolving pulp after filtration include: filtration value is 140-150 L / h, particle number ≤70, secondary glue block ≤18. Among them, "filtration value" refers to the volume (L) of the melt passing through the filter per unit time (h); "particle number" refers to the number of undissolved impurities with a diameter greater than 10µm, counted under a microscope; "secondary glue block" refers to the number of undissolved raw pulp boards after passing through the filter; S2 spinning: passing the filtered cellulose dissolving pulp obtained in step S1 into a spinning device with a pore size of 0.15-0.25 mm, controlling the hot air volume of the Roots blower in the upper air duct of the spinning device to 1000-1300 Hz and the temperature to 95-98° C., and controlling the die temperature of the spinning device to 95-98° C., to obtain fiber filaments; Wherein, after the filtered cellulose dissolving pulp obtained in step S1 passes through the holes of the spinneret, the dissolving pulp is gradually stretched under the action of hot air, and finally forms fiber filaments; The indicators of fiber filaments include: diameter of 2-7.5 µm; the diameter is concentrated in 3.5-6.5 µm, accounting for 80-88%; S3 blowing: using a laying conveyor belt to receive the fiber filaments obtained in step S2, and using transverse cold air with a humidity of 75-90% RH, a temperature of 25-27° C., and an air volume of 200-400 Hz to blow the fiber filaments on both sides of the fiber filaments between the filament outlet of the spinning device and the laying conveyor belt; The distance between the outlet of the spinning device and the web laying conveyor is 10-16cm, and the web forming speed of the motor of the web laying conveyor is 150-180m / min. The high humidity cold air is used, and the fibers of the ejected filaments become thinner and fixed under the action of the high humidity cold air, and the web is laid on the receiving web laying conveyor; The indicators of the fiber web on the web laying conveyor belt include: solvent residue ≤3%, monofilament ratio 99-99.5%; S4 spraying: The received fiber web is sent to the spraying device through the web laying conveyor belt; at the spraying station, it is washed with deionized water; In this spraying process, the water pressure is controlled at 20-30 bar and the water temperature is 20-26℃; After spraying, the fiber web indicators are: whiteness is 75-85%, solvent residue is ≤3%; S5 spunlace: the washed fiber web is fed into the spunlace machine; at the spunlace station, the fiber web is spunlace to obtain the primary product of regenerated cellulose ultrafine fiber nonwoven fabric; In the hydroentanglement process, the water pressure is controlled at 65-75 bar and the water temperature is 15-26°C to further enhance the strength of the nonwoven fabric; After spunlacing, the indicators of the initial non-woven fabric include: transverse strength of 40-48N / 60gsm, transverse elongation at break of 48-55% / 60gsm, longitudinal strength of 75-80 N / 60gsm, longitudinal elongation at break of 50-55% / 60gsm; S6 Drying: The primary non-woven fabric is fed into the dryer; in the drying station, moisture is removed to obtain the regenerated cellulose microfiber non-woven fabric product, which can be rolled up, packaged, etc. according to demand; In the drying process, the temperature is controlled at 75-90°C.

[0007] Preferably, the solvent waste liquid formed in the spinning, blowing and spraying processes is recovered and directly used to dissolve the raw material-pulp board.

[0008] The second purpose of the technical solution is to provide: a preparation system of ultrafine fiber nonwoven fabric based on regenerated cellulose, comprising a cellulose dissolving pulp tank, a filtering device, a spinning device, a web laying conveyor, a spraying device, a spunlacing machine and a drying machine; The cellulose dissolving pulp tank is arranged at the front side of the station of the filtering device, and the cellulose dissolving pulp tank is connected to the filtering device through a twin-screw extruder; The spinning device is arranged at the rear side of the station of the filtering device, and the filtering device is connected to the spinning device; the spinning device is connected to a hot air blower (such as a Roots blower) through a hot air pipe; The web laying conveyor is arranged below the spinning device, the distance between the upper thread outlet of the spinning device and the web laying conveyor is 10-16 cm, and a transverse cold air blowing device is arranged between the upper thread outlet of the spinning device and the web laying conveyor, and the transverse cold air blowing device is connected to a water vapor inlet pipe; the air outlets of the transverse cold air blowing device are distributed on both sides of the silk strip, and a continuous passage for silk strip outlet, cold air blowing and receiving is formed between the upper thread outlet of the spinning device and the web laying conveyor; The spray device is arranged at the rear side of the working position of the web laying conveyor, and the web laying conveyor extends to the spray working position below the spray device through the web laying conveyor belt; The hydroentanglement machine is located behind the spraying device, and the web laying conveyor extends to the hydroentanglement station below the hydroentanglement machine; The dryer is located behind the hydroentanglement machine, and the web laying conveyor belt extends to the feed port of the dryer; A continuous passage for preparing the ultrafine fiber nonwoven fabric is formed between the cellulose dissolving pulp tank, the twin-screw extruder, the filtering device, the spinning device, the transverse cold air blowing device, the web laying conveyor, the spraying device, the spunlace machine and the drying machine.

[0009] Furthermore, a dissolving pulp buffer barrel is provided at the rear side of the station of the cellulose dissolving pulp tank, and the dissolving pulp tank outlet is connected to the dissolving pulp buffer barrel, and the dissolving pulp buffer barrel outlet is connected to the feeding port of the twin-screw extruder. By setting the dissolving pulp buffer barrel, the dissolving pulp is buffered, which can better connect the cellulose dissolving pulp tank and the twin-screw extruder, thereby ensuring the orderliness and stability of the discharging of the cellulose dissolving pulp tank and the feeding of the twin-screw extruder.

[0010] Furthermore, a metering pump is provided between the filtering device and the spinning device to improve the controllability and meterability of the spinning process.

[0011] Furthermore, the horizontal cold air blowing device includes an air outlet mechanism and a ventilation duct, the air outlet mechanism is connected to the ventilation duct, and the air outlet is arranged at the end of the ventilation duct; the water vapor inlet pipe is connected to a humidifier, the water vapor inlet pipe is connected to the ventilation duct, the cold air is humidified by the humidifier, and the humidified air is cooled down the wire strip through the air outlet.

[0012] Furthermore, there are multiple air outlets evenly distributed on both sides of the filaments, so as to evenly blow cold air to the filaments ejected from the outlets on the spinneret device.

[0013] Furthermore, a solvent collecting tank I is provided below the web conveyor, and a solvent collecting tank II is provided below the spray device. Both solvent collecting tank I and solvent collecting tank II are connected to the cellulose dissolving pulp tank through a reflux pipe to realize solvent recovery and reuse. More preferably, the recovered solvent contains impurities, so it needs to be filtered, purified, and then reused. Among them, solvent recovery and purification can effectively reduce production costs. The equipment involved mainly includes an evaporator, that is, the solvent collecting tank I is connected to the evaporator through a reflux pipe, the solvent collecting tank II is connected to the evaporator through a reflux pipe, and the evaporator discharge port is connected to the cellulose dissolving pulp tank.

[0014] The positional relationships involved in this technical solution, such as "rear side of the workstation", "between", "front side of the workstation", "below", and "above", are defined according to the actual usage conditions. They are conventional terms in this technical field and are also conventional terms used by technical personnel in this field in actual use.

[0015] In the description of the present technical solution, it should be noted that, unless otherwise clearly specified and limited, "setting" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0016] The beneficial technical effects brought about by adopting this technical solution are: 1. The present invention is based on the melt-blowing method, which not only obtains a melt-blown nonwoven fabric of regenerated cellulose ultrafine fibers, but also has uniform fiber diameter and concentrated diameter distribution in the obtained melt-blown nonwoven fabric of regenerated cellulose ultrafine fibers, thereby avoiding the shortcomings of "high fiber adhesion, film formation in more areas, small number of monofilaments in the nonwoven fabric, and part of the monofilaments embedded in the film, and part of the monofilaments highly cross-bridged between the films", so as to meet the actual needs; 2. In the present invention, by controlling the spinning process, it is ensured that 97-99% of the solvent (N-methylmorpholine-N-oxide, NMMO) is removed instantly when the dissolving pulp is ejected from the spinneret hole, the dissolving pulp stream is more easily deformed under the action of the airflow, and the degree of entanglement between the fibers is reduced. Therefore, the final form of the fiber is maintained after regeneration, that is, the fiber diameter is 2-7.5µm, and the fiber diameter is concentrated in 3.5-6.5µm (accounting for 80-88%); In addition, the residual solvent (1-3%) is removed in time through the horizontal cold air and water washing process, maintaining the final shape of the regenerated fiber, that is, ensuring the preparation of melt-blown nonwoven fabrics with concentrated fiber diameter and uniform appearance; 3. In the present invention, the forming of ultrafine fibers is achieved by controlling the blowing process; the removal of solvents in ultrafine fibers is achieved by controlling the spraying process; the reinforcement of ultrafine fiber webs is achieved by controlling the spunlacing process; and the drying process is controlled to dry the wet nonwoven fabric after spunlacing ultrafine fibers, which is convenient for subsequent treatment. Fourth, in the present invention, an orderly, stable and controllable production of ultrafine fiber nonwoven fabrics based on regenerated cellulose is achieved through an adapted preparation system, including a cellulose dissolving pulp tank, a twin-screw extruder, a filtering device, a spinning device, a transverse cold air blowing device, a web laying conveyor, a spraying device, a spunlacing machine and a drying machine; 5. The preparation process of the ultrafine fiber non-woven fabric involved in the present invention has the characteristics of high efficiency and short process, and the production system involved has high integration, and the obtained product has the advantages of fine fibers and softness. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a process flow chart of the present invention; Figure 2 This is a working principle diagram of the present invention; Figure 3 It is a working principle diagram of the spinning and blowing processes in the present invention; Figure 4 It is a schematic diagram of the equipment layout of the preparation system of the present invention; Figure 5 This is an electron microscope scanning image of a portion of the ultrafine fiber nonwoven fabric involved in the present invention; In the figure, 1, cellulose dissolving pulp tank, 2, twin-screw extruder, 3, filtering device, 4, spinning device, 5, transverse cold air blowing device, 6, web conveyor, 7, spraying device, 8, spunlace machine, 9, dryer, 10, hot air pipe, 11, water vapor inlet pipe, 12, filament strip, 13, web conveyor belt, 14, dissolving pulp buffer barrel, 15, metering pump, 16, solvent collecting tank I, 17, solvent collecting tank II, 18, reflux pipe, 19, hot air blower, 20, evaporator. DETAILED DESCRIPTION

[0018] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] In the prior art, when preparing melt-blown nonwoven fabrics of regenerated cellulose ultrafine fibers, the fiber bonding degree is high, more areas form thin films, the number of monofilaments in the nonwoven fabric is small, and some monofilaments are embedded in the thin films, while some monofilaments are highly cross-bridged between the films.

[0020] To this end, by timely removing most of the solvent (N-methylmorpholine-N-oxide, NMMO), the dissolving pulp flow is easier to deform under the action of airflow, and the degree of entanglement between fibers is reduced. Therefore, the final form of the fiber is maintained after regeneration, that is, the fiber diameter is 2-7.5µm, and the fiber diameter is concentrated in 3.5-6.5µm; and, through transverse cold air and water washing, the remaining solvent (1-3%) is removed in time, maintaining the final form of the regenerated fiber, that is, ensuring the preparation of melt-blown non-woven fabrics with concentrated fiber diameters and uniform appearance.

[0021] The invention is specifically described by the following examples.

[0022] The testing standards for fiber whiteness, transverse strength of non-woven fabrics, transverse elongation at break of non-woven fabrics, longitudinal strength of non-woven fabrics and longitudinal elongation at break of non-woven fabrics involved in the following examples are all: FZ / T 64033.

[0023] And, the fiber fineness involved was measured by scanning electron microscopy (JEOL, Japan, model JSM-IT300A), where a scanning electron microscope (SEM) was used to observe and analyze the microscopic surface morphology of the sample. Before the test, a layer of about 10 nm gold film was plated on the surface of the sample by vacuum deposition, and a voltage of 15 kV was used for detection.

[0024] Example 1 This embodiment provides: a preparation process of a superfine fiber nonwoven fabric based on regenerated cellulose, such as Figure 2 As shown, including: S1 filtration: the cellulose dissolving pulp is passed through a twin-screw extruder into a filter device with a filter mesh diameter of 0.04-0.06 mm, and filtered to obtain a filtered cellulose dissolving pulp; Among them, a twin-screw extruder is used to further dissolve and disperse the dissolving slurry, so as to further eliminate the bubbles in the dissolving slurry and further dissolve the undissolved impurities, which is beneficial to the stability of subsequent spinning and the improvement of the quality of the final filaments. And the temperature in the twin-screw extruder is controlled: the temperature of zone one is 95-98°C, the temperature of zone two is 95-98°C, the temperature of zone three is 95-98°C, and the temperature of zone four is 95-98°C. Further limitation of the temperature of each zone ensures that the twin screw homogenizes the dissolving slurry and dissolves the undissolved impurities again, thereby improving the dissolution uniformity of the dissolving slurry and effectively reducing the impact of impurities on the stability of subsequent spinning. The indicators of the filtered cellulose dissolving pulp include: filtration value 140-150L / h, particle number ≤70, secondary glue block ≤18; S2 Spinning: Figure 3 As shown, the cellulose dissolving pulp obtained after filtering in step S1 is passed into a spinning device with a pore size of 0.15-0.25 mm, the hot air volume of the Roots blower in the upper air duct of the spinning device is controlled to be 1000-1300 Hz and the temperature is controlled to be 95-98° C., and the die temperature of the spinning device is controlled to be 95-98° C., to obtain fiber filaments; Wherein, after the filtered cellulose dissolving pulp obtained in step S1 passes through the holes of the spinneret, the dissolving pulp is gradually stretched under the action of hot air, and finally forms fiber filaments; The indicators of fiber filaments include: diameter of 2-7.5 µm; the diameter is concentrated in 3.5-6.5 µm, accounting for 80-88%; S3 blowing: using a web conveyor belt to receive the fiber filaments obtained in step S2, and using transverse cold air with a humidity of 75-90% RH, a temperature of 25-27° C., and an air volume of 200-400 Hz to blow the fiber filaments on both sides of the fiber filaments between the filament outlet of the spinning device and the web conveyor belt (such as Figure 3 shown); The distance between the outlet of the spinning device and the web laying conveyor is 10-16cm, and the web forming speed of the motor of the web laying conveyor is 150-180m / min. The high humidity cold air is used, and the fibers of the ejected filaments become thinner and fixed under the action of the high humidity cold air, and the web is laid on the receiving web laying conveyor; The indicators of the fiber web on the web laying conveyor belt include: solvent residue ≤3%, monofilament ratio 99-99.5%; S4 spraying: The received fiber web is sent to the spraying device through the web laying conveyor belt; at the spraying station, it is washed with deionized water; In this spraying process, the water pressure is controlled at 20-30 bar and the water temperature is 20-26℃; After spraying, the fiber web indicators are: whiteness is 75-85%, solvent residue is ≤3%; S5 spunlace: the washed fiber web is fed into the spunlace machine; at the spunlace station, the fiber web is spunlace to obtain the primary product of regenerated cellulose ultrafine fiber nonwoven fabric; In the hydroentanglement process, the water pressure is controlled at 65-75 bar and the water temperature is 15-26°C to further enhance the strength of the nonwoven fabric; After spunlacing, the indicators of the initial non-woven fabric include: transverse strength of 40-48N / 60gsm, transverse elongation at break of 48-55% / 60gsm, longitudinal strength of 75-80 N / 60gsm, longitudinal elongation at break of 50-55% / 60gsm; S6 Drying: The primary non-woven fabric is fed into the dryer; in the drying station, moisture is removed to obtain the regenerated cellulose microfiber non-woven fabric product, which can be rolled up, packaged, etc. according to demand; In the drying process, the temperature is controlled at 75-90°C.

[0025] In addition, the solvent waste liquid generated in the spinning, blowing and spraying processes is recovered and directly used to dissolve the raw material-pulp board.

[0026] Example 2 Based on Example 1, this example provides: a system for preparing ultrafine fiber nonwoven fabric based on regenerated cellulose, such as Figure 4 As shown, it includes a cellulose dissolving pulp tank 1, a filtering device 3, a spinning device 4, a web laying conveyor 6, a spraying device 7, a spunlacing machine 8 and a drying machine 9; The cellulose dissolving pulp tank 1 is arranged at the front side of the station of the filtering device 3, and the cellulose dissolving pulp tank 1 is connected to the filtering device 3 through a twin-screw extruder 2; the spinning device 4 is arranged at the rear side of the station of the filtering device 3, and the filtering device 3 is connected to the spinning device 4; the spinning device 4 is connected to a hot air blower 19 (such as a Roots blower) through a hot air pipe 10; the web laying conveyor 6 is arranged below the spinning device 4, and the distance between the spinning device 4 and the web laying conveyor 6 is 10-16cm, and a transverse cold air blowing device 5 is arranged between the spinning device 4 and the web laying conveyor 6, and the transverse cold air blowing device 5 is connected to a water vapor inlet pipe 11; the air outlets of the transverse cold air blowing device 5 are distributed on both sides of the filament 12, and a continuous passage for the filament 12 to be discharged, blown with cold air and received is formed between the spinning device 4 and the web laying conveyor 6; The spray device 7 is arranged at the rear side of the working position of the web laying conveyor 6, and the web laying conveyor 6 extends to the spraying position below the spray device 7 through the web laying conveyor belt 13; the spunlacing machine 8 is arranged at the rear side of the working position of the spray device 7, and the web laying conveyor belt 13 extends to the spunlacing position below the spunlacing machine 8; the dryer 9 is arranged at the rear side of the working position of the spunlacing machine 8, and the web laying conveyor belt 13 extends to the feed port of the dryer 9; A continuous passage for preparing ultrafine fiber nonwoven fabric is formed between the cellulose dissolving pulp tank 1, the twin-screw extruder 2, the filtering device 3, the spinning device 4, the transverse cold air blowing device 5, the web laying conveyor 6, the spraying device 7, the spunlace machine 8 and the drying machine 9.

[0027] Furthermore, a dissolving pulp buffer barrel 14 is provided at the rear side of the station of the cellulose dissolving pulp tank 1, and the discharging port of the cellulose dissolving pulp tank 1 is connected to the dissolving pulp buffer barrel 14, and the discharging port of the dissolving pulp buffer barrel 14 is connected to the feeding port of the twin-screw extruder 2. By setting the dissolving pulp buffer barrel 14, the dissolving pulp is buffered, which can better connect the cellulose dissolving pulp tank 1 and the twin-screw extruder 2, thereby ensuring the orderliness and stability of the discharging of the cellulose dissolving pulp tank 1 and the feeding of the twin-screw extruder 2.

[0028] Furthermore, a metering pump 15 is provided between the filtering device 3 and the spinning device 4 to improve the controllability and meterability of the spinning process.

[0029] Furthermore, the horizontal cold air blowing device 5 includes an air outlet mechanism and a ventilation duct, the air outlet mechanism is connected to the ventilation duct, and the air outlet is arranged at the end of the ventilation duct; the water vapor inlet pipe 11 is connected to a humidifier, and the water vapor inlet pipe 11 is connected to the ventilation duct. The cold air is humidified by the humidifier, and the humidified air cools the wire strip 12 through the air outlet.

[0030] Furthermore, there are multiple air outlets evenly distributed on both sides of the filament 12, so as to evenly blow cold air to the filament 12 ejected from the outlet of the spinneret 4.

[0031] Furthermore, a solvent collecting tank I16 is provided below the web conveyor 6, and a solvent collecting tank II17 is provided below the spray device 7. Both the solvent collecting tank I16 and the solvent collecting tank II17 are connected to the cellulose dissolving pulp tank 1 through a reflux pipe 18 to realize the recovery and reuse of the solvent. More preferably, the recovered solvent contains impurities, so it needs to be filtered, purified, and then reused. Among them, solvent recovery and purification can effectively reduce production costs. The equipment involved mainly includes an evaporator 20, that is, the solvent collecting tank I16 is connected to the evaporator 20 through a reflux pipe 18, the solvent collecting tank II17 is connected to the evaporator 20 through a reflux pipe 18, and the discharge port of the evaporator 20 is connected to the cellulose dissolving pulp tank 1.

[0032] Example 3 This embodiment combines actual production to demonstrate the debugging process and results in part of the production process to further illustrate the technical solution.

[0033] A preparation process of ultrafine fiber nonwoven fabric based on regenerated cellulose, such as Figure 1 As shown, the specific steps include: 1) Using pulp as raw material, the cellulose dissolving pulp is obtained through pulp cutting, mixing, pre-dissolving and dissolving; 2) The cellulose dissolving pulp is passed through a twin-screw extruder and then passed into a filtering device for filtering to obtain filtered cellulose dissolving pulp. The number of subsequent spinneret blockages involved in adding a twin-screw extruder and not adding a twin-screw extruder is counted, and the results are shown in Table 1 below; Table 1 shows the number of subsequent spinneret plugging results It can be further known that: the shear force of the twin-screw extruder is used to dissolve some of the undissolved impurities again, and the stirring effect of the twin-screw is used to homogenize the dissolved slurry, thereby improving the stability of subsequent spinning; The indicators of cellulose dissolving pulp before filtration are shown in Table 2 below; Table 2 Cellulose dissolving pulp indicators (before filtration) The indicators of the cellulose dissolving pulp after filtration are shown in Table 3 below; Table 3 Cellulose dissolving pulp indicators (after filtration) 3) The filtered cellulose dissolving pulp is passed into a spinneret with a pore size of 0.15-0.25 mm, the hot air volume of the Roots blower in the upper air duct of the spinneret is controlled to be 1000-1300 Hz and the temperature is controlled to be 95-98°C, and the die head temperature of the spinneret is controlled to be 95-98°C to obtain fiber filaments. After the filtered cellulose dissolving pulp passes through the holes of the spinneret, the dissolving pulp is gradually stretched under the action of hot air, and finally, fiber filaments are formed; the results of the control conditions involved are shown in Table 4-5 below; Table 4 Effect of control conditions on subsequent processes and final product performance Table 5 Statistical results of fiber fineness 4) Using a web-laying conveyor belt to receive fiber filaments, and using transverse cold air with a humidity of 75-90%RH, a temperature of 25-27°C, and an air volume of 200-400Hz to blow the fiber filaments on both sides of the fiber filaments between the outlet of the spinneret and the web-laying conveyor belt. The distance between the outlet of the spinneret and the web-laying conveyor belt is 10-16cm, and the web-laying speed of the motor of the web-laying conveyor belt is 150-180m / min. The test results of the fiber web on the web-laying conveyor belt are shown in Table 6. Table 6 Test results of the fiber web formed after blowing 5) The received fiber web is sent to a spraying device through a web laying conveyor belt; at the spraying station, the fiber web is washed with deionized water; wherein the washing conditions involved are shown in Table 7 below; Table 7 Washing conditions And, the test results of the fiber web after washing are shown in Table 8; Table 8 Test results of fiber web after washing 6) feeding the washed fiber web into a spunlacing machine; spunlacing at the spunlacing station to obtain a primary regenerated cellulose ultrafine fiber nonwoven fabric; wherein the spunlacing conditions are shown in Table 9 below; Table 9 Hydroentanglement conditions And, the test results of the initial nonwoven fabric formed after spunlacing are shown in Table 10; Table 10 Test results of non-woven fabric (weight: 60gsm) 7) The non-woven fabric is fed into a dryer; in the drying station, water is removed to obtain a regenerated cellulose microfiber non-woven fabric product (such as Figure 5 As shown), it can be rolled up, packaged, etc. according to the needs; wherein the drying conditions involved are shown in Table 11; Table 11 Drying conditions Discussion Example This discussion example is based on Example 3 and discusses as follows: 1. The main control point of the preparation process of ultrafine fiber non-woven fabric based on regenerated cellulose is to control the aperture of the spinneret. The aperture of the spinneret is generally 0.15-0.38 mm, which can control the diameter distribution of the melt-blown fiber, as shown in Table 12 below Table 12 shows the melt-blown cellulose ultrafine fibers with different spinneret apertures. It can be seen that under the same test conditions, as the aperture of the spinneret increases, the fiber diameter gradually increases. Therefore, in order to ensure the stable production and product quality of ultrafine fiber non-woven fabrics, a spinneret with an aperture of 0.15-0.25 mm is selected.

[0034] Second, by controlling the air volume of the hot air blower, the fiber diameter and its distribution range can be adjusted within a certain range. Specifically, a 0.25mm aperture spinneret was used as the test condition, and the fiber diameters under different hot air volumes were statistically analyzed, as shown in Table 13 below; Table 13 shows the fiber diameters of the 0.25 mm aperture spinneret at different hot air volumes It can be seen that under the same test conditions, as the air volume of the hot air blower increases, the fiber diameter gradually decreases. Therefore, in order to ensure the stable production and product quality of ultrafine fiber non-woven fabrics, the air volume of the hot air blower is selected to be 1000-1300Hz.

[0035] 3. After the spinning solution exits the spinneret, hot air is used to draw the spinning solution. At the same time, transverse cold air is used to cool the ejected filaments, so that the solute is precipitated and the nascent fibers are hot-drawn. The transverse cold air is used to evenly shape the fibers over the entire width. 4. The solvent can be recovered through the suction device, and the recovered solvent can be used again after filtering and purification. According to the test, the solvent recovery rate can reach 99%; 5. Wash the prepared fiber web through a spray device to remove the solvent on the fiber surface and ensure that there is no solvent residue on the fiber. According to testing, the solvent recovery rate here can reach 0.1%. The recovered solvent can be used again after filtering and purification; 6. After washing, the solvent recovery rate can reach more than 99%, realizing solvent recovery and reuse; In summary, fiber quality is closely affected by the aperture of the spinneret and the hot air volume. In addition, the influencing factors are not limited to the aperture of the spinneret and the hot air volume, but also affected by the cold air humidity, cold air temperature, cold air volume, web forming distance (the distance between the outlet of the spinneret and the web laying conveyor belt), etc., which will not be discussed one by one.

[0036] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A process for preparing ultrafine fiber nonwoven fabric based on regenerated cellulose, characterized in that: The steps include: S1 filtration: the cellulose dissolving pulp is passed through a twin-screw extruder into a filter device with a filter mesh aperture of 0.04-0.06 mm, and filtered to obtain a cellulose dissolving pulp with a filtration value of 140-150 L / h, a particle number of ≤70, and a secondary rubber block of ≤18; S2 spinning: passing the filtered cellulose dissolving pulp obtained in step S1 into a spinning device with a pore size of 0.15-0.25 mm, controlling the hot air volume of the Roots blower in the upper air duct of the spinning device to 1000-1300 Hz and the temperature to 95-98° C., and controlling the die temperature of the spinning device to 95-98° C., to obtain fiber filaments; S3 blowing: using a laying conveyor belt to receive the fiber filaments obtained in step S2, and using transverse cold air with a humidity of 75-90% RH, a temperature of 25-27° C., and an air volume of 200-400 Hz to blow the fiber filaments on both sides of the fiber filaments between the filament outlet of the spinneret and the laying conveyor belt; S4 spraying: The received fiber web is sent to the spraying device through the web laying conveyor belt; at the spraying station, it is washed with deionized water to obtain a fiber web with a whiteness of 75-85% and a solvent residue of ≤3%; S5 spunlace: the washed fiber web is fed into the spunlace machine; in the spunlace station, spunlace is performed to obtain a microfiber nonwoven fabric having a transverse strength of 40-48N / 60gsm, a transverse elongation at break of 48-55% / 60gsm, a longitudinal strength of 75-80 N / 60gsm, and a longitudinal elongation at break of 50-55% / 60gsm; S6 Drying: The non-woven fabric is fed into the dryer; at the drying station, the drying temperature is controlled at 75-90°C to obtain the ultra-fine fiber non-woven fabric product.

2. The process for preparing the ultrafine fiber nonwoven fabric based on regenerated cellulose according to claim 1, characterized in that: In step S1, the temperature in the twin-screw extruder is controlled to be: 95-98°C in zone 1, 95-98°C in zone 2, 95-98°C in zone 3, and 95-98°C in zone 4.

3. The process for preparing the ultrafine fiber nonwoven fabric based on regenerated cellulose according to claim 1, characterized in that: In step S2, the diameter of the obtained fiber filaments is 2-7.5 µm; the diameter is concentrated in the range of 3.5-6.5 µm, accounting for 80-88%.

4. The process for preparing the ultrafine fiber nonwoven fabric based on regenerated cellulose according to claim 1, characterized in that: In step S3, the distance between the spinning outlet on the spinning device and the web laying conveyor belt is 10-16 cm, and the web forming speed of the motor of the web laying conveyor belt is 150-180 m / mi; the indicators of the fiber web on the web laying conveyor belt include: solvent residue ≤3%, and monofilament ratio 99-99.5%.

5. The process for preparing the ultrafine fiber nonwoven fabric based on regenerated cellulose according to claim 1, characterized in that: In step S4, the water pressure is controlled to be 20-30 bar and the water temperature is controlled to be 20-26°C.

6. The process for preparing the ultrafine fiber nonwoven fabric based on regenerated cellulose according to claim 1, characterized in that: In step S5, the water pressure is controlled to be 65-75 bar and the water temperature is controlled to be 15-26°C.

7. The process for preparing the ultrafine fiber nonwoven fabric based on regenerated cellulose according to claim 1, characterized in that: The solvent waste liquid generated in the spinning, blowing and spraying processes is recovered and used to dissolve the raw material - pulp board.

8. A system for preparing ultrafine fiber nonwoven fabric based on regenerated cellulose, characterized in that: A preparation system used in the preparation process according to any one of claims 1 to 7, the preparation system comprising a cellulose dissolving pulp tank (1), a filtering device (3), a spinning device (4), a web conveyor (6), a spraying device (7), a spunlacing machine (8) and a drying machine (9); The cellulose dissolving pulp tank (1) is arranged at the front side of the working station of the filtering device (3), and the cellulose dissolving pulp tank (1) is connected to the filtering device (3) through a twin-screw extruder (2); the spinning device (4) is arranged at the rear side of the working station of the filtering device (3), and the filtering device (3) is connected to the spinning device (4); the spinning device (4) is connected to a hot air blower (19) through a hot air pipe (10); the web laying conveyor (6) is arranged below the spinning device (4), and a transverse cold air blowing device (5) is arranged between the upper thread outlet of the spinning device (4) and the web laying conveyor (6), and the transverse cold air blowing device (5) is connected to a water vapor inlet pipe (11); the air outlets of the transverse cold air blowing device (5) are distributed on both sides of the filament (12), and a continuous passage for the filament (12) to be discharged, blown with cold air and received is formed between the upper thread outlet of the spinning device (4) and the web laying conveyor (6); The spray device (7) is arranged at the rear side of the working position of the web laying conveyor (6), and the web laying conveyor (6) extends to the spraying position below the spray device (7) through the web laying conveyor belt (13); the spunlacing machine (8) is arranged at the rear side of the working position of the spray device (7), and the web laying conveyor belt (13) extends to the spunlacing position below the spunlacing machine (8); the drying machine (9) is arranged at the rear side of the working position of the spunlacing machine (8), and the web laying conveyor belt (13) extends to the feed port of the drying machine (9); A continuous passage for preparing ultrafine fiber nonwoven fabric is formed between the cellulose dissolving pulp tank (1), the twin-screw extruder (2), the filtering device (3), the spinning device (4), the transverse cold air blowing device (5), the web laying conveyor (6), the spraying device (7), the spunlace machine (8) and the drying machine (9).

9. The system for preparing ultrafine fiber nonwoven fabric based on regenerated cellulose according to claim 8, characterized in that: The horizontal cold air blowing device (5) comprises an air outlet mechanism and a ventilation pipe, the air outlet mechanism is connected to the ventilation pipe, and the air outlet is arranged at the end of the ventilation pipe; the water vapor inlet pipe (11) is connected to a humidifier, and the water vapor inlet pipe (11) is connected to the ventilation pipe; There are multiple air outlets, which are evenly distributed on both sides of the wire strip (12).

10. The system for preparing ultrafine fiber nonwoven fabric based on regenerated cellulose according to claim 8, characterized in that: A solvent collecting tank I (16) is provided below the web-laying conveyor (6), and a solvent collecting tank II (17) is provided below the spraying device (7). The solvent collecting tank I (16) is connected to the evaporator (20) via a reflux pipe (18), and the solvent collecting tank II (17) is connected to the evaporator (20) via a reflux pipe (18). The discharge port of the evaporator (20) is connected to the cellulose dissolving pulp tank (1).

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