CZ2015327A3 - Apparatus for producing fibers or microfibers - Google Patents

Abstract

Equipment for the production of nanofibres or microfibres from solutions, emulsions, liquid suspensions or melting containing spinning substance consists of a chamber (1) in which a hollow shaft (3) is mounted, on which at least one rotating disk (2) with an outlet gap is fixed ( 4). As a rule, the chamber (1) is provided with a gas flow source (11) and a collecting space (12). In an alternative embodiment, the chamber (1) is provided with a plurality of hollow shafts (3) arranged side by side on which rotating disks (2) are mounted, preferably with at least two superposed rotating disks (2). The at least one rotating disk (2) is formed by two successive parts (7, 8). An outlet gap (4) is formed circumferentially between the upper part (7) and the lower part (8). The size of the exit gap (4) between the upper part (7) and the lower part (8) of the rotating disk (2) can be formed by a spacer (13), in particular a spacer ring.

Description

Fiber / Ball Fiber Manufacturing Technology

BACKGROUND OF THE INVENTION The present invention relates to a device for producing nanofibres or microfibres from solutions, emulsions, liquid suspensions or melts containing a spun substance.

BACKGROUND OF THE INVENTION [0002] A number of devices for electrospinning solutions, emulsions, liquid suspensions or melts containing a spinning substance are currently available. Systems producing nanofibers including jet and non-jet configurations are described. These devices are structurally demanding and operate with a number of drawbacks, including nozzle clogging, resulting in interruption of production or limitation of production productivity. In non-jet devices, nanofibers are formed directly from the surface of the spinning solutions, which can be in the form of a thin film. Two-layer systems are also used, where the backsheet is a ferromagnetic suspension and the topsheet is a spinning polymer solution. After the application of the magnetic field, sharp vertical cones of the ferromagnetic fluid are formed, which serve as nuclei from which nanofibers are formed.

Another device is based on aeration of the spinning polymer solution with the aim to create a high concentration of bubbles on the surface of the solution, where the surface tension decreases and the bubbles form nuclei of nanofibres produced by the electric field.

Another device emanates from a slowly rotating roller which is partially immersed in the spinning polymer solution. When the cylinder is rotated, a certain amount of solution is applied to the cylinder and the result is a continuous film from which the so-called Taylor cones, acting as nuclei of nanofibres, are created by the action of a strong electric field.

Electrostatic spinning methods are characterized by low process speed, technically complicated and costly. Electrospinning is limited by the need to apply a high voltage electric field. • * ···· ----

Devices that do not come out of the application of electrostatic spinning are also used. As a rule, centrifugal force or gas flow is used for the formation of nanofibres. A rotating disc is used, on the surface of which a thin film of the spinning solution is formed by centrifugal force.

SUMMARY OF THE INVENTION

The aforementioned disadvantages of the apparatus for producing fibers or microfibers from solutions, emulsions, liquid suspensions, or melt-containing slurries can be largely eliminated by the solution of the invention, which consists of a chamber in which a hollow shaft is mounted on which at least one rotating disk is mounted with an exit gap.

As a rule, the chamber is provided with a source of flowing gas and a collection space. Alternatively, the chamber is provided with a plurality of hollow shafts arranged side by side on which rotating discs are mounted.

It is preferred that at least one hollow shaft is provided with at least two superposed rotating disks. The at least one rotating disk is formed by two successive parts, wherein an exit gap is formed circumferentially between the upper part and the lower part. The size of the exit gap, between the upper portion and the lower portion of the rotating disk, may be formed by a spacer, in particular a spacer ring.

Preferably, at least one portion of the rotating disc is frustoconical. The at least one rotating disk may be provided with a pressure element, for example a pressure nut. At least one disk (s) located in the chamber made of a heat resistant material may be provided with a device for heating them.

The inner space of the hollow shaft communicates with the outlet gap of each of the rotating disks through the openings and at the other end with the polymer feed rotation unit and further with the drive motor.

The source of the flowing gas in the chamber is a compressor or a fan. The collection space may be either a moving belt of breathable fabric, or a rotating collector or bag of porous mesh. The collection area may be electrically charged. .....

Compared to the prior art, the invention prevents drying of polymeric solution films on the surface of rotating discs. It reduces the amount of defects in the produced nanofibrous and microfibrous layers, especially drops. It facilitates the centrifugal spinning of the melt because the melt does not cool on the surface of the rotating elements. BRIEF DESCRIPTION OF THE DRAWINGS An exemplary embodiment of a device for producing nanostructured or microstructured materials is shown in the accompanying drawings, in which: Figure 1 shows the overall engagement of the whole apparatus; Figure 2 shows a spindle with a hollow shaft and a disc in axonometric view and partial longitudinal section; Fig. 4 shows a particular embodiment of a disc according to the invention with a spacer. Example 1. Preparation of nano or microfibers from a solution of polyvinyl alcohol.

A commercial solution of polyvinyl alcohol Sloviol R16, 16% (w / w) of dry matter (Fichema) was used to prepare polyvinyl alcohol micro or nanofibers. The polyvinyl alcohol solution was pumped from the first liquid reservoir 17 by the first pump 18 through the connecting hose 19 through the first relief valve 20 and the first check valve 21 at a rate of 2 to 12 ml / min. and fed through the liquid inlet 22 to the rotary unit 10, from which it has further entered the hollow shaft 3, stored in the spindle tube 5. The holes 16 were injected from the inner space 6 of the hollow shaft 3 into the interior of the rotating disk 2 of the conical shape, 120 mm in diameter, between the upper part 7 and the lower part 8. The exit gap 4 of the conical disk 2 was adjusted using a spacer ring 13 4. The rotating disk 2 was positioned above the base plate 23 with channels 32 for distributing the drying gas into the chamber 1 in the form of a plexiglass tube 5 having a diameter of 35 cm and a height of 40 cm. Drying air preheated to 25 ° C from the source en formed by the compressor and the heater entered the base plate 23 at a rate of 0.7 m 3 / s. The rotating disk 2 with the hollow shaft 3 was rotated through the intermediate gear 15 by the drive motor 14 at a speed of 1 to 5,000 rpm. The preheated air stream carried nano or microfibers. formed by centrifugal force on the edge of the exit gap, 4 into the collection space 12, provided with a screen with a slit width of 24 cm and a length of 35 cm and a sliding belt 25 breathable nonwoven, spunbond fabric with a weight of 18, 8 g / m. The web feed rate was 10 cm / min. Nano or microfibers were deposited in the form of a continuous layer on the surface of the sliding belt 25 of the breathable fabric. At a constant flow rate of polyvinyl alcohol solution of 10 ml / min. the rate of fiber formation increased with increasing disc speed ranging from 1 to 3,000 rpm. As the speed increased further, the fiber formation rate no longer increased, and the occurrence of droplet defects in the fibrous web increased. Therefore, further experiments were performed at a rotational speed of 3,000 rpm. At this speed of rotation and other conditions described above, the basis weight of the fibers increased in a linear manner over a flow rate of the polyvinyl alcohol solution of 2 to 8 ml / min. Maximum productivity was observed at a flow rate of 10 ml / min. A further increase in flow rate to 12 ml / min under the conditions described above was already counterproductive, fiber production productivity and the use of polyvinyl alcohol no longer increased, but slightly decreased. The occurrence of defects in the form of microdroplets also increased. Flow rates in the range of 8 to 10 ml / min appeared to be optimal under the conditions. Under these conditions, the basis weight of the polyvinyl alcohol fiber layer was in the range of 7 to 10 g / m 2. The maximum fiber formation rate at a flow rate of 8 ml / min and a rotation speed of 3,000 rpm was 20 g per hour. The distribution of nanofibers was homogeneous on a microscopic and macroscopic scale over the entire width of the strip, which was 35 cm. The diameter of most of the observed fibers ranged from 400 to 800 nanometers. The procedure described above was repeated except that two rotating disks 2 of the same design were placed on one hollow shaft 3 one above the other with a spacing of 10 cm and the flow rate of the polyvinyl alcohol solution and the belt shift 25 of the breathable fabric was doubled. Under these conditions, the fiber formation rate at a flow rate of 16 ml / min and a rotation speed of 3,000 rpm was increased to 38 g per hour. There were no significant changes in fiber weight or quality. Example 2. Preparation of nano or microfibers from polyamide 6.

Polyamide 6 pellets (Rhodia Technyl) were used to prepare polyamide 6 micro or nanofibers. From these pellets, a 15% (w / w) solution in 85% (w / w) formic acid (Penta) was prepared at 80 ° C. This solution was pumped from the first liquid reservoir 17 by the first pump 18 through the connecting hose 19 through the first safety valve 20 and the first ... return valve 2 at 6 to 16 ml / min. and fed through the liquid inlet 22 to the rotary unit 10, from which it further entered the hollow shaft 3, housed in the spindle tube 5. The holes 16 were injected from the inner space 6 of the hollow shaft 3 into the inner space of the rotating disk 2 between its upper part 7 and the lower part 8. A cone-shaped disc 120 mm in diameter was used, with a pressing element 9 in the form of a nut, as Figure 3 shows the pressure of the pressure nut in order to open the outlet gap 4 at an overpressure of between 4 and 400 bar. The rotating disk 2 was placed above the base plate 23 with channels 32 for distributing the drying gas into the chamber 5 of a Plexiglas tube 5 cm in diameter and 40 cm in height. Drying air preheated to 35 ° C from source 1T, consisting of a compressor and a heater, entered the base plate 23 at a rate of 0.6 m / s. The rotating disk 2 with the hollow shaft 3 was rotated through the intermediate gear 15 by a drive motor 14 at a speed of 1 to 5,000 rpm. The preheated air stream carried the nano or microfibers generated by the centrifugal force at the edge of the exit gap 4 into the collecting chamber 12 scalded with a screen with a slit width of 24 cm and a length of 35 cm. At a height of 5 mm above the aperture slot 24, a rotary fiber collector in the form of a 10 cm fine steel wire mesh with a 10 rpm motor was horizontally positioned horizontally.

The nano or microfibers were deposited evenly over the entire surface of the rotary collector in the form of a continuous layer of almost 3 mm thick in the form of a fine cotton wool. With increasing pressure in the inner space of the disc 2 between its upper part 7 and the lower part 8, the fiber diameter decreased. While at a pressure of 4 bar the fiber diameter was in the range of 600 to 900 nm, at a pressure of 400 bar the diameter was already in the range of 200 to 400 µm. The fiber formation rate ranged from 50 g to 135 g per hour, depending on the conditions. The optimum flow rate was 14 ml / min. In another experiment, a Plexiglas chamber of cuboid shape with a length of 2 m and a width and height of 50 cm was used, in which two rotating disks 2 were placed side by side with pressure elements 9 in the form of nuts. The disks 2 were placed 1 m apart. Optimal spinning conditions of the polyamide 6 solution were determined as described above. The flow in each disk was 14 ml / min. The pressure in the inner space of the disks 2 between its upper part 7 and the lower part 8 was 60 bar. The collection of fibers in the collecting space 12 was carried out using a screen with a slit width of 24 20 cm and a length of 2 m and a sliding band 25 of the breathable non-woven Spunbond fabric with a weight of 18.8 g / m, also a width of 2 m. cm / min. The nano or microfibers were deposited in the form of a continuous layer on the surface of the web 25 of the breathable fabric. The distribution of nanofibers was homogeneous on a microscopic and macroscopic scale over the entire width of the strip, which was 35 cm. The diameter of most of the observed fibers ranged from 300 to 500 nanometers. The basis weight of the fibers ranged from 4 to 6 g / m 2. Example 3. Encapsulation of probiotic bacteria into gelatin microfibers

For encapsulation of probiotic bacteria, a 10% (w / w) suspension of BA microbial preparation (1.109 CFU / g) (Milcom) containing probiotic strains of the genera Lactobacillus acidophillus and Bifldobacterium bifldum lyophilized with dried milk in distilled water was used. Next, a solution of 30% (w / w) porcine gelatin, 300 bloom, type A (Sigma-Aldrich) in 40% (v / v) acetic acid was used. A gelatin solution of 45 ° C was pumped from the first liquid reservoir 17 by the first pump 18 through a connecting hose 19 via a first relief valve 20 and a first check valve 21 at a rate of 5 ml / min. At the same time, the second liquid reservoir 26 was pumped from the second liquid reservoir 26 through the second hose 27 via a second safety valve 28 and a second check valve 29 at a rate of 5 ml / min. bacterial suspension. The gelatin solution and the bacterial suspension were mixed in a 5 ml mixing chamber 30. The bacterial suspension obtained in the gelatin solution was fed through the liquid inlet 22 to the rotary unit 10, from which it further entered the hollow shaft 3 mounted in the spindle tube 5. The holes 16 were further injected from the inner space 6 of the hollow shaft 3 into the inner space of the rotating disk 2 of conical shape, 120 mm in diameter, between its upper part 7 and the lower part 8. The exit gap 4 of the conical disk 2 was adjusted using the spacer 13 4. The rotating disk 2 was positioned above the base plate 23 with channels 32 for distributing the drying gas into the chamber 1 in the form of a fine steel mesh tube with a diameter of 35 cm and a height of 40 cm. Drying air preheated to 40 ° C from a source 11 consisting of a compressor and a heater entered the base plate 23 at a rate of 0.8 m 3 / s.

The rotating disk 2 with the hollow shaft 3 was rotated through the intermediate gear 15 by the drive motor 14 at a speed of 3500 rpm. The preheated air stream carried the nano or microfibers generated by the centrifugal force at the edge of the exit gap 4 of the rotating disk 2 to a collection chamber 12 scored with a slit width 24 of 10 cm above which a Spunbond nonwoven bag weighing 18.8 g / m 2 was placed. The microfibers were collected in this bag in the form of a soft thick cotton wool. 80 g of microfibers with encapsulated bacterial culture were obtained in one hour of operation of the device. Microscopic analysis confirmed the presence of bacterial cells encapsulated within microfibers with a diameter of 5 to 10 microns. By standard methods of microbiological analysis, it was found that there was only a slight decrease in the original vitality of the bacterial culture, expressed by the number of column forming units (ktj), by one order. Microbiological tests have confirmed a significant protective effect of encapsulation against the simulated acidic environment of the stomach and against the action of bile acids. Example 4. Preparation of polyhyroxyalkanoate melt fibers

The polyhyroxyalkanoate melt (Nanjing Huichen Co., Ltd., China) was prepared in a first solution tank 17 equipped with induction heating and maintained at 300 degrees Celsius. The entire equipment was thermally insulated.

The melt was pumped from the first liquid reservoir 17 by the first pump 18 through an insulated steel profiled strip connecting hose 19 through the first safety valve 20 and the first check valve 21 at a rate of 10 ml / min. and fed through the liquid inlet 22 to the rotary unit 10, from which it further entered the hollow shaft 3, housed in the spindle tube 5. The openings 16 were melt injected from the interior of the hollow shaft 6 into the inner space of the rotating disk 2 of conical shape, 120 mm in diameter, between its upper part 7 and the lower part 8. The exit gap 4 of the conical disk 2 was adjusted using a spacer element 13 in width 4. The rotating disk 2 was placed above the base plate 23 with channels 32 for distributing drying gas into chamber 1 in the form of a steel insulated tube having a diameter of 35 cm and a height of 40 cm. Drying air preheated to 250 ° C from source 11, which consists of a compressor and a heater, entered the base plate 23 at a rate of 1 m / s. The rotating disk 2 with the hollow shaft 3 was rotated through the intermediate gear 15 by the drive motor 14 at a speed of 1 to 5,000 rpm. The preheated air stream carried the nano or microfibers generated by the centrifugal force at the edge of the exit gap 4 into the collecting chamber 12 scalded with a screen with a slit width of 24 cm and a length of 35 cm and a sliding belt of fine steel mesh.

The basis weight of the fibers ranged from 8 to 10 g / m 2. The distribution of nanofibers was homogeneous on a microscopic and macroscopic scale over the entire width of the strip, which was 35 cm. The majority of the fibers observed were in the range of 400 to 800 nanomere. The fiber production rate was 600 g per hour.

Industrial usability

The device for producing fibers or microfibres from solutions, emulsions, melts or liquid suspensions containing the spinning polymer according to the invention can be used in the production of nanofibres or microfibers where high labor productivity is required due to avoiding drying of polymeric solution films on the surface of rotating discs and reduced defects of the fiber layers. . The device also facilitates centrifugal spinning of the melt, as the melt does not cool on the surface of the rotating elements.

List of reference numbers 1 - chamber 2 - disk 3 - hollow shaft 4 - exit gap 5 - tube 6 - inner space 7 - upper part 8 - lower part 9 - pressure element 10 - rotary unit 11 - flowing gas source 12 - collecting space 13 - spacer 14 - drive motor 15 - intermediate gear 16 - holes 17 - first reservoir 18 - first pump 19 - connection hose 20 - first safety valve 21 - first check valve 22 - liquid inlet 23 - base plate 24 - slot 25 - belt 26 - second container 27 - second pump 28 - second safety valve 29 - second non-return valve 30 - mixing chamber 31 - heating device 32 - gas distribution channel

Claims (15)

PATENT CLAIMS 1. Equipment for the production of nanofibres or microfibres from solutions, emulsions, liquid suspensions or melts containing a spinning substance, characterized in that it consists of a chamber (1) in which a hollow shaft (3) is mounted, on which at least one is mounted rotating disk (2) with exit gap (4). Device for producing nanofibers or microfibers according to claim 1, characterized in that the chamber (1) is provided with a flowing gas source (11) and a collecting space (13). Device for producing nanofibers or microfibers according to claim 1, characterized in that the chamber (1) is provided with several side-by-side hollow shafts (3) on which the rotating disks (2) are mounted. Device for producing nanofibers or microfibers according to claim 1, characterized in that at least one hollow shaft (3) is provided with at least two superposed rotating disks (2). 5. Apparatus for producing nanofibers or microfibers according to claim 1, characterized in that at least one rotating disc (2) is formed by two successive parts (7, 8), wherein between the upper part (7) and the lower part (8) an outlet gap (4) is formed circumferentially. Device for producing nanofibers or microfibers according to claim 5, characterized in that the size of the exit gap (4) between the upper part (7) and the lower part (8) of the rotating disk (2) is formed by a spacer (13) , in particular by a spacer ring. A device for producing nanofibers or microfibers according to claims 1 and 5, characterized in that at least one part of the rotating disc (2) has the shape of a truncated cone. A device for producing nanofibers or microfibers according to claim 1, 4 and 5, characterized in that at least one rotating disc (2) is provided with a pressing element (9). Device for producing nanofibers or microfibers according to claim 6, characterized in that the pressing element (9) is a pressing nut. 10. Apparatus for producing nanofibers or microfibers according to claim 1, characterized in that the inner space (6) of the hollow shaft (3) is interconnected by openings (16) with the inner space of each of the rotating disks between their upper part (7). and the lower part (8) and the exit gap (4). The device for producing nanofibers or microfibers according to claim 1, characterized in that the hollow shaft (3) is connected to a rotating unit (10) allowing the supply of liquid or melt containing the spinning substance and further with the drive motor (14). Device for producing nanofibers or microfibers according to claim 1, characterized in that the source (11) of the flowing gas in the chamber (1) is a compressor or a fan. Device for producing nanofibers or microfibers according to claim 2, characterized in that the collecting space (12) is either a movable web (25) of nonwoven fabric, or a rotating collector or bag of porous mesh. 14. Apparatus for producing nanofibers or microfibers according to claim 2, characterized in that the collecting space (12) is electrically charged. 15. Apparatus for producing nanofibers or microfibers according to claim 1, characterized in that the rotating disk (s) (2) placed in the chamber (1) made of heat-resistant material are provided with a device for heating them.