Spinning method and apparatusTechnical Field
The present invention relates to a spinning method for a fiber containing a polymer, the spinning method including a step of discharging a polymer solution from a nozzle tip, wherein spinning is performed while supplying a gas containing a vapor of the same solvent as that of the polymer solution to the periphery of the polymer solution immediately after the discharge, and an apparatus used for the spinning method.
Background
In recent years, molded articles such as sheets made of nanofibers have attracted attention as materials having properties not possessed by conventional fiber molded articles because of their high specific surface area. As a method for producing nanofibers (spinning method) as described above, electrospinning is widely known.
The electrospinning method is a method in which a solution (dope) obtained by dissolving a polymer in a solvent is supplied to the tip of a dope discharge nozzle, and a high voltage is applied between the tip of the nozzle and an electrode (collector), thereby obtaining a fiber molded body on the collector. The method comprises the following steps: a step of dissolving a polymer in a solvent to prepare a solution (spinning dope), a step of supplying the spinning dope to a nozzle tip and applying a high voltage, a step of ejecting the spinning dope from the nozzle tip toward an electrode (collector), a step of forming a fiber molded body by evaporating the solvent from the ejected spinning dope, a step of eliminating charges of the formed fiber molded body as an optional step, and a step of accumulating the fiber molded body on the collector by eliminating the charges.
In the electrospinning method, there is a problem that continuous production is possible even when a volatile solvent is used in the spinning solution. In this regard, patent document 1 discloses a technique of surrounding a nanofiber being produced with a solvent in the vicinity of a single-tube nozzle in the conventional technique, and physically preventing and/or cleaning the adsorption of the produced nanofiber to the nozzle by a solvent flow, thereby enabling continuous production.
Documents of the prior art
Patent document
Patent document 1: japanese patent application laid-open No. 2010-236133.
Disclosure of Invention
Problems to be solved by the invention
The present inventors have found that, in the electrospinning method, when a volatile solvent is used as a solvent for the spinning solution, a taylor cone (generally a cone shape) formed at the tip of a nozzle is solidified in a step of ejecting the spinning solution from the tip of the nozzle (when the tip of the nozzle is generated during spinning, a voltage exceeding the surface tension is applied to liquid droplets supplied to the tip of the nozzle, and the liquid droplets are stretched in the voltage direction, and this solidified solid matter grows with time, which causes a problem that the spinning stability is deteriorated, the spinning yield is lowered, and the continuous production is not possible. Further, it is known that the above-mentioned problems are not limited to the electrospinning method, but are commonly caused in the spinning method in which a polymer solution is spun in a gas.
The present invention has been made to solve the above problems, and an object of the present invention is to provide a method and an apparatus for suppressing solidification of a dope at a nozzle tip in a spinning method in which a polymer solution is spun in a gas while suppressing solidification, growth, or the like of a taylor cone in electrospinning.
Means for solving the problems
As a result of intensive studies in view of the above-described problems, the present inventors have found that a nozzle device provided with a device for supplying a polymer solution as a fiber raw material to a nozzle and a device for supplying a solvent vapor of the polymer solution to the tip of the nozzle as a nozzle device in a spinning apparatus can suppress solidification of a spinning solution at the tip of the nozzle in a spinning method in which the spinning solution is discharged in a gas by supplying the solvent vapor of the polymer solution to the vicinity of the tip of the nozzle and supplying the polymer solution as a fiber raw material to the nozzle to prepare a fiber, thereby completing the present invention.
That is, the present invention is as follows.
[1] A spinning nozzle device is provided with a nozzle, a polymer solution supply device for supplying a polymer solution to the nozzle and discharging the polymer solution from the tip of the nozzle, and a solvent vapor supply device for supplying a gas containing vapor of the same solvent as the solvent of the polymer solution to at least the periphery of the polymer solution immediately after the discharge.
[2] [1] A nozzle device for spinning, comprising: the gas supply device has a double-pipe structure portion including an inner pipe as a nozzle and an outer pipe surrounding the inner pipe, and supplies a gas containing a vapor of the same solvent as the solvent of the polymer solution from a space between the inner pipe and the outer pipe.
[3] A spinning method for a polymer-containing fiber comprising a step of discharging a polymer solution from the tip of a nozzle, wherein spinning is performed while supplying a gas containing a vapor of the same solvent as the solvent of the polymer solution to at least the periphery of the polymer solution immediately after discharge.
[4] [3] the spinning method according to claim 3, wherein the supplied gas contains a substance that is in a gas phase under the conditions used in spinning, and the vapor of the same solvent as the solvent of the polymer solution is saturated in the supplied gas.
ADVANTAGEOUS EFFECTS OF INVENTION
The present invention has an effect that, in a spinning method in which a polymer solution is spun in a gas, solidification of a spinning solution at the tip of a nozzle from which the spinning solution is discharged can be suppressed. This can reduce clogging or poor discharge of the fiber component at the tip of the nozzle, improve spinning stability and spinning yield, and enable continuous production.
Drawings
FIG. 1 is a schematic view of an entire apparatus for producing a fiber by an electrospinning method using a double-tube nozzle as an example of a nozzle device of the present invention.
Fig. 2 shows a nozzle device having a double pipe structure as an example of the nozzle device of the present invention.
Detailed Description
In the nozzle device of the present invention, as a device for supplying a polymer solution (spinning solution) as a fiber material to a nozzle, a device which is generally used as a nozzle device in a spinning device for spinning a polymer solution in a gas can be used. The device for supplying the solvent vapor of the spinning solution to the tip of the nozzle is not particularly limited, but a device that does not interfere with the formation of the taylor cone in the spinning direction during the electrospinning method is preferable, and for example, a device having the following configuration can be used: the spinning device has an inner tube for supplying a spinning solution as a nozzle and an outer tube surrounding the inner tube, and supplies a gas containing a vapor of a spinning solution solvent from a space between the inner tube and the outer tube in a direction substantially the same as a direction in which the spinning solution is discharged from the nozzle. Thereby, at least the polymer solution immediately after the ejection is placed in the atmosphere of the solvent vapor.
In the production method of the present invention, as the step of ejecting the polymer solution from the tip of the nozzle, a method generally used in a spinning method of spinning the polymer solution in a gas can be used. In addition, as the step of supplying the gas containing the vapor of the same solvent as the solvent of the polymer solution to at least the periphery (vicinity) of the polymer solution immediately after the discharge, a method of forming a taylor cone in the spinning direction at the time of spinning is preferably adopted in the electrospinning method, and for example, a method of blowing the gas containing the solvent of the spinning solution to the periphery of the discharged spinning solution in the direction almost the same as the direction in which the spinning solution is discharged from the nozzle can be adopted.
The present invention can be applied to any spinning technique for producing a fiber by vaporizing a solvent from a spinning solution, and can be used, for example, in an electrospinning method, a solution jet spinning method, or a force spinning (force spinning) method, and is preferably used in the electrospinning method.
Examples of the polymer usable in the present invention include various polymers soluble in a certain solvent as follows: polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile-methacrylate copolymer, polymethyl methacrylate, polyvinyl chloride, polyvinylidene chloride-acrylate copolymer, polyethylene, polypropylene, nylon-based materials such as nylon 12, nylon-4, 6, etc., aromatic polyamides, polybenzimidazole, polyvinyl alcohol, cellulose acetate butyrate, polyvinylpyrrolidone-vinyl acetate, poly (bis- (2- (2-methoxy-ethoxyethoxy)) phosphazene), polypropylene oxide, polyethyleneimine, polyethylene succinate, polyaniline, polyethylene sulfide, polyoxymethylene-oligoethylene oxide, SBS copolymer, polyhydroxybutyric acid, polyvinyl acetate, polyethylene terephthalate, polyethylene oxide, collagen, polylactic acid, polyglycolic acid, poly D, L-lactic acid-glycolic acid copolymer, biodegradable polymers such as polyarylate, polypropylene fumarate and polycaprolactone, biopolymers such as polypeptide and protein, asphalt systems such as coal tar pitch and petroleum pitch, and the like.
The solvent of the polymer solution is the same as the solvent used as the solvent vapor, and examples of the usable solvent include acetone, chloroform, ethanol, 2-propanol, methanol, toluene, tetrahydrofuran, water, benzene, benzyl alcohol, 1, 4-dioxane, 1-propanol, carbon tetrachloride, cyclohexane, cyclohexanone, dichloromethane, phenol, pyridine, trichloroethane, acetic acid, N-dimethylformamide, dimethyl sulfoxide, N-dimethylacetamide, 1-methyl-2-pyrrolidone, ethylene carbonate, propylene carbonate, dimethyl carbonate, acetonitrile, N-methylmorpholine-N-oxide, butylene carbonate, 1, 4-butyrolactone, diethyl carbonate, diethyl ether, 1, 2-dimethoxyethane, and 1, 3-dimethyl-2-imidazolidinone, 1, 3-dioxolane, ethyl methyl carbonate, methyl formate, 3-methyloxazolidin-2-one, methyl propionate, 2-methyltetrahydrofuran, sulfolane, and a mixed solvent of 2 or more selected from these solvents.
The nozzle having a double-tube structure according to the present invention preferably has an inner diameter of 0.15 to 1.07mm, more preferably 0.34 to 0.84 mm. The outer diameter of the double-pipe nozzle, which is a portion for ejecting the solvent vapor, is preferably 1.00 to 2.00mm, and more preferably 1.30 to 1.70 mm. If the nozzle inner diameter and the outer ring inner diameter are outside these ranges, a cured product is likely to be generated at the nozzle tip.
The flow rate range of the polymer solution is not particularly limited as long as it is a spinnable range, and is preferably set within a range of from 20 ml/h.
The partial pressure of the solvent vapor to be used may be, for example, within a range of 1/2 or more of the saturated vapor pressure of the solvent, and the solvent vapor is preferably saturated. If the solvent saturated vapor is out of this range, a cured product is likely to be generated at the nozzle tip.
The gas flow rate of the solvent vapor is preferably 100 to 1000ml/min, and more preferably 200 to 800 ml/min. If the gas flow rate is outside this range, a cured product is likely to be generated at the tip of the nozzle.
Examples
[ preparation apparatus ]
FIG. 1 is an example of the overall configuration of a fiber production facility by an electrospinning method using a nozzle device of the present invention. FIG. 2 is a schematic cross-sectional view of an example of a nozzle device of the present invention. In these figures, the nozzle device is composed of a nozzle and its outer tube, and has the structure: the nozzle is connected to a supply device for a raw material solution for fibers, the outer tube is connected to a supply device for a solvent vapor of the raw material solution, the raw material solution for fibers is discharged from the nozzle, and the vapor of the solvent for the raw material solution is released from a space between the nozzle and the outer tube so as to surround the discharged solution.
[ preparation of Polymer solution for spinning ]
1 part by weight of poly (lactic acid-co-glycolic acid) (PURASORB PDLG5010 manufactured by Purac), 1 part by weight of ethanol (Wako pure chemical industries, Ltd.), and 0.0042 parts by weight of pigment D & C Violet NO.2 (Spectrum Chemem. MFG. Corp.) were weighed and put into a reagent bottle (medium bottle), followed by stirring for 5 minutes at the scale 10 with a vortex mixer SI 0286. Then, 8 parts by weight of methylene chloride was added, and the mixture was stirred with a vortex mixer SI0286 at a scale of 10 for 1 minute and with a high viscosity stirrer SNF-01 at 1000rpm for 10 minutes, thereby obtaining a uniform polymer solution for spinning.
[ spinning Using Polymer solution for spinning ]
Electrospinning was performed using the spinning solution obtained above. The spinning was carried out using a double tube nozzle having an inner diameter of 0.47mm and an outer diameter of 1.45mm, the number of nozzles being 12, the pitch interval between the nozzles being 70mm, the distance between the spinnerets being 400mm, the flow rate of the spinning solution being 4ml/h, and the spinning applied voltage being 35 kV. On the fiber collecting side, a collecting plate made of SUS304 was used in a size of 330 mm. times.440 mm, and a voltage of-5 kV was applied to the collecting plate. During spinning, 300ml/h of compressed air (0.3MPa) was supplied into a 3L glass sealed vessel in which 500ml of methylene chloride was sealed, and 300ml/h of saturated methylene chloride vapor was supplied into the space between each nozzle and the outer tube. Under these conditions, even if spinning was continued for 25 minutes, no solid was produced at the nozzle tip.
[ comparative example ]
Spinning was performed under the same conditions as in the above examples, except that saturated methylene chloride vapor was not supplied to the space between the nozzle and the outer tube at the time of spinning. Under these conditions, a solid component was generated at the nozzle tip immediately after the start of spinning, and the solid component was grown at the nozzle tip 40 seconds after the start of spinning, and thus spinning could not be continued.
Industrial applicability
The present invention is useful as a spinning method and apparatus which are excellent in spinning stability and spinning yield and which can be used for continuous production, for example, in the production of nonwoven fabrics.
Description of the reference numerals
1 quantitative feeder
2 Syringe
3 connecting hose
4 double nozzle
5 connecting hose
6 solvent bubble bottle
7 control needle valve
8 volume flowmeter
9 gas supply part
10 supply port of raw material solution (spinning solution)
11 a supply port for a gas containing a solvent vapor.