JP4831350B2 - Electrospinning method - Google Patents

Description

In this invention, by injecting a polymer solution from an injection portion at the tip of a storage case toward a collector, the solution is stretched based on a potential difference to spin ultrafine fibers, thereby producing a web used for a filter or the like. it relates to the other electric field spinning method.

  Conventionally, as this type of electrospinning apparatus, ones having configurations as disclosed in, for example, Patent Document 1 and Patent Document 2 have been proposed. In the conventional apparatus of Patent Document 1, a nozzle for injecting a polymer solution and a barrel for storing the polymer solution are heated with a heating band, and the temperature of the polymer solution in the nozzle is a temperature from 40 degrees Celsius to the boiling point of the solvent or less. Keep in range. Further, the relative humidity of the operation space (the space between the nozzle and the barrel) is adjusted to a predetermined value (for example, 25%), and spinning is performed in this state.

In the conventional apparatus disclosed in Patent Document 2, air is jetted from an air nozzle toward a yarn discharging nozzle from which a polymer solution is discharged during spinning.
JP 2002-249966 A JP 2005-520068 Gazette

However, these conventional electrospinning apparatuses have the following problems.
First, in the conventional apparatus of Patent Document 1, the entire storage case and the nozzle are heated. For this reason, the heating time for the polymer solution is long, and it is difficult to spin ultrafine fibers using a polymer solution that is unstable to heat and easily deteriorates. Therefore, the type of polymer that can be used is limited, and it is not possible to deal with many types of polymers. In addition, when the polymer solution is heated in the storage case, the viscosity of the polymer solution in the storage case decreases. Therefore, when the polymer solution is spun by mixing fine powders such as functional materials (for example, activated carbon or ceramic) As a result, aggregation of fine powder is likely to occur, and it has been difficult to spin a fiber containing a functional material in a uniform dispersion state. Furthermore, there is a possibility that the nozzle is clogged due to aggregation of the fine powder.

  Further, in the conventional electrospinning method of Patent Document 2, hot air is jetted onto the drawn polymer solution, so that the solvent in the polymer solution is not contained in the spinning space (operation space) including the vicinity of the nozzle injection portion. Volatilization is promoted. For this reason, the viscosity of the drawn polymer solution becomes high, and the drawn solution cannot be sufficiently stretched, making it difficult to spin ultrafine fibers. By the way, when the spun web is used for a filter such as an air filter, the thinner the fibers constituting the web, the lower the pressure loss of the filter and the finer the filter, and the higher the filtration function. be able to. Therefore, according to the method of Patent Document 2, it is difficult to obtain a filter having a high filtering function. Further, according to the method of Patent Document 2, since the viscosity of the polymer solution is increased, the injection portion of the nozzle is likely to be clogged, and the resin flying is unstable due to the polymer lump solidified in the vicinity of the injection portion. Thus, it is difficult to create a web having a uniform density.

  On the other hand, when it is configured not to perform hot air injection or the like, the solvent is difficult to volatilize, so that the fibers are flat on the collector, and spread in a flat shape particularly at the intersection of the fibers. This tendency is remarkable in a polymer solution using a high-boiling solvent that hardly volatilizes. As described above, when the fibers are flattened, when the web is used as a filter, the porosity is reduced, pressure loss is increased, and clogging is likely to occur.

  Furthermore, when fibers are spun onto a substrate having a functional material (for example, activated carbon or ceramic), if there is a residual non-volatile solvent, the functional material is altered due to the solvent (for example, activated carbon micropores are clogged). The function of the material may be reduced.

The present invention has been made paying attention to such problems existing in the prior art. The purpose of this invention is to promote the volatilization of the solvent on the collector to provide a Ru electric field spinning method can solve the conventional problems described above.

In order to achieve the above object, in the electrospinning method of the present invention, electrospinning is performed on the collection surface on the collector by injecting the polymer solution from the injection part at the tip of the storage case toward the collector. In the electrospinning method as described above, the collection surface is heated to a temperature equal to or higher than the boiling point of the solvent of the polymer solution. Therefore, since the collection surface is heated to a temperature equal to or higher than the boiling point of the solvent of the polymer solution, volatilization of the solvent on the collection surface can be promoted. Therefore, even if it is a polymer solution using a solvent that hardly volatilizes such as a high boiling point solvent, it can be prevented from becoming flat on the collection surface.

  In the electrospinning method, the collection surface is a surface of a spinning base material positioned around the collector, and if the surface of the spinning base material is heated to the softening temperature of the spinning base material, spinning is performed. The adhesion between the ultrafine fiber and the spinning substrate can be improved.

  Furthermore, in the above electrospinning method, if the spinning space between the injection part and the collector is at room temperature, volatilization of the solvent in the vicinity of the injection part can be suppressed. Therefore, polymer clumps formed in the vicinity of the injection part can be prevented, and therefore, there is no risk of unstable flying of the drawn polymer solution, and a web with a uniform density of ultrafine fibers is created. can do.

  As described above, according to the present invention, it is possible to perform electrospinning that can process ultrafine fibers even with a polymer solution that uses a solvent that hardly volatilizes by promoting the volatilization of the solvent on the collection surface. Demonstrate the effect.

(First embodiment)
Below, 1st Embodiment of this invention is described based on FIG.
As shown in FIG. 1, a collector 12 made of a metal roller such as stainless steel or aluminum alloy is supported in the housing 11 and is continuously rotated in one direction by a motor (not shown). In the housing 11, a syringe pump 13 as a storage case made of an insulating material such as glass is opposed to the side of the collector 12, and a polymer solution 14 is accommodated in the syringe pump 13. A needle 15 as an injection portion made of metal for injecting the polymer solution 14 is attached to the tip of the syringe pump 13. Then, the polymer solution 14 in the syringe pump 13 is ejected from the tip opening of the needle 15 toward the collector 12. A power source 16 is connected to the needle 15 so that a high voltage is applied, and a charge is given to the polymer solution 14. The collector 12 is grounded. Therefore, a potential difference is applied between the needle 15 and the collector 12 through a space. The polymer solution 14 injected from the tip 15a of the needle 15 is extracted based on the potential difference and electrospun.

One or a plurality of syringe pumps 13 are installed, and in the case of a plurality of syringe pumps 13, they are installed along the axial direction of the collector 12 at intervals from each other in a direction perpendicular to the paper surface of FIG.
On the outer side of the housing 11, a feeding roller 22 is provided for feeding a spinning base material 21 such as filter paper or nonwoven fabric to the outer periphery of the collector 12 in the housing 11. Then, the polymer solution 14 from the needle 15 is collected and collected as ultrafine fibers on the surface of the spinning substrate 21 that is circulated around the outer periphery of the collector 12 to form a web-like fiber layer 19 made of ultrafine fibers. Is done. Therefore, on the collector 12, the fiber laminated body 20 which consists of the said spinning base material 21 and the fiber layer 19 of the surface is produced. Therefore, the surface of the spinning substrate 21 becomes a collecting surface for collecting and accumulating ultrafine fibers. A winding roller 25 is disposed on the outer side of the housing 11, and the fiber laminate 20 is wound around the winding roller 25 via a guide roller 26.

  At the center of the collector 12, a heater 18 is provided as a heating means. The heater 18 heats the surface of the spinning substrate 21 as a collection surface on the collector 12 to a softening temperature of the spinning substrate 21 that is equal to or higher than the boiling point of the solvent of the polymer solution 14. For example, the collector 12 is heated by the heater 18 so that the surface temperature of the collection surface of the spinning substrate 21 is in the range of 50 to 250 ° C.

In this case, the spinning space between the needle 15 and the collector 12 in the housing 11 is maintained at room temperature.
When spinning from the polymer solution 14 for a filter, the polymer of the polymer solution 14 includes water-soluble polymers represented by polyvinyl alcohol, proteins such as polylactic acid and gelatin, polysaccharides such as starch, and the like. There are several biodegradable polymers. As the solvent for these polymers, dichloromethane, chloroform, water, or a mixed solvent of water and alcohol is generally used. Therefore, the boiling point of the solvent is 100 degrees Celsius or less. For example, when the spinning base material 21 is polypropylene, the softening temperature varies depending on the molecular weight or the like, but is, for example, 150 degrees Celsius. Therefore, the collection surface is heated to 150 degrees Celsius. When the polymer is polyacrylonitrile, polyurethane, or polystyrene, dimethylformamide (boiling point 153 degrees Celsius), dimethylacetamide (boiling point 165 degrees Celsius), or dimethyl sulfoxide (boiling point 189 degrees Celsius) is used. In this case, for example, polyester (softening temperature of about 200 to 230 degrees Celsius) is preferable as the spinning base material 21.

Next, the operation of the electrospinning apparatus configured as described above will be described.
When the electrospinning apparatus is operated, the spinning space between the needle 15 and the collector 12 is set to room temperature, and the spinning base 22 is rotated from the feeding roller 22 by the rotation of the collector 12 while the collector 12 is heated. The material 21 is fed out and circulated around the outer periphery of the collector 12. At this time, the polymer solution 14 is injected from the tip 15 a of the needle 15 toward the spinning base 21 on the outer periphery of the collector 12. The injected polymer solution 14 is spun while being spun based on the potential difference, and a web-like fiber layer 19 is formed on the surface of the substrate 21 by spinning. By forming the fiber layer 19, the fiber laminate 20 is produced, and the fiber laminate 20 is wound around the take-up roller 25 via the guide roller 26.

Here, the first embodiment has the following effects.
(1) Since the surface of the spinning substrate 21, that is, the collection surface is heated to a temperature equal to or higher than the boiling point of the solvent of the polymer solution 14, it is possible to promote the volatilization of the solvent in the collected state. . Therefore, it becomes possible to spin a polymer solution using a solvent that hardly volatilizes such as a high boiling point solvent, and the types of polymer solutions that can be spun can be increased. Moreover, since the solvent can be volatilized in a short time on the collection surface, the functional material can be prevented from being altered.

  (2) In a state where the spun ultrafine fibers are collected on the surface of the spinning substrate, the solvent is immediately volatilized by heat. For this reason, it is possible to prevent the ultrafine fibers 14a from being unnecessarily integrated or flattened. Therefore, when using the fiber laminate 20 as a filter, the filter can be made finer, while the porosity can be increased and the increase in the pressure loss of the filter can be suppressed. The filtration function can be enhanced.

  (3) When the polymer of the polymer solution 14 is a thermosetting resin or protein, by setting the heating temperature of the collector 12 high, the polymer curing reaction and denaturation can be performed simultaneously with the collection. It is also possible to improve productivity.

  (4) The spinning space around the collector 12 is maintained at room temperature. For this reason, volatilization of the solvent in the polymer solution 14 in the vicinity of the tip 15a of the needle 15 is suppressed, and the polymer solution 14 exiting the tip 15a of the needle 15 is prevented from immediately solidifying. Therefore, the polymer solution 14 can be effectively stretched, and spinning made of ultrafine fibers becomes possible. In addition, since the volatilization of the solvent in the spinning space is suppressed, there is no possibility that the polymer solution 14 will become unstable due to a lump of polymer solidified in the vicinity of the tip 15a, and the workability of the ultrafine fibers 14a. Can be maintained, and a web of ultrafine fibers 14a having a uniform density can be produced.

  (5) Since it is not necessary to heat the syringe pump 13, it is possible to spin ultrafine fibers using the polymer solution 14 that is unstable to heat and easily deteriorates, and the polymer solution 14 in the syringe pump 13. Can be maintained at a high level. For this reason, when the polymer solution 14 is spun with a fine powder of a functional material such as activated carbon mixed, spinning of the fine powder can be prevented. Therefore, not only can the fibers containing the functional material contained in a uniformly dispersed state be spun, but also the possibility of clogging the nozzles can be prevented.

  (6) Since the surface temperature of the spinning base material 21 is raised to the softening temperature of the spinning base material 21, the spun ultrafine fibers 14 a are easily integrated with the surface of the spinning base material 21. Therefore, the fiber laminate 20 in which the spinning base material 21 and the ultrafine fibers 14a are firmly bonded can be produced.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with a focus on differences from the first embodiment.
In the electrospinning apparatus according to the second embodiment, a pair of preheating rollers 31 are disposed on the upstream side of the collector 12 in the housing 11 as shown in FIG. These preheating rollers 31 have a heater 32 therein. These preheating rollers 31 sandwich the spinning base material 21 supplied to the collector 12 and heat the spinning base material 21 in advance.

Therefore, in the second embodiment, even when the spinning base material 21 is moved at a high speed, the spinning base material 21 can be appropriately heated to perform spinning.
(Third embodiment)
Next, a third embodiment will be described.

  In the third embodiment, as shown in FIG. 3, the collector 12 is composed of a pair of rollers 27 and an endless belt 28 made of a thin metal plate that is stretched between the rollers 27. The endless belt 28 is connected to the ground. The needle 15 faces the endless belt 28 in the portion between the rollers 27, and spinning is performed on the spinning base material 21 on the endless belt 28 between the rollers 27. A heater 43 for heating the collecting surface is disposed at the back surface position of the endless belt 28 in the portion between the rollers 27.

  Therefore, in the third embodiment, since spinning is performed on the spinning base material 21 in a flat state, the fiber layer 19 can be formed smoothly and smoothly along the surface of the spinning base material 21. .

(Example of change)
In addition, this embodiment can also be changed and embodied as follows.
-As a means for heating the collecting surface of the ultrafine fibers, a means for radiatively heating the collecting surface is used.

  -As a roller which comprises the collector 12, the porous thing which consists of sintered metals etc. should be used. If it does in this way, it will become possible to make the spinning base material 21 contact | adhere to the collector 12 by attracting | sucking air from the slit of a sintered metal.

Sectional drawing which shows the electrospinning apparatus of 1st Embodiment. Sectional drawing which shows the electrospinning apparatus of 2nd Embodiment. Sectional drawing which shows the electrospinning apparatus of 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 12 ... Collector, 13 ... Storage case, 14 ... Polymer solution, 14a ... Fine fiber, 15 ... Needle, 15a ... Tip part, 16 ... High voltage, 18 ... Heater as a heating means, 21 ... Spinning base material, 23 ... Fiber Layer, 24 ... fiber laminate.

Claims (2)

In the electrospinning method in which electrospinning is performed on the collection surface on the collector by injecting the polymer solution from the injection part at the tip of the storage case toward the collector,
The surface of the spinning substrate located around the collector is the collection surface,
A method of electrospinning , wherein the surface of the spinning substrate is heated to a boiling point of a solvent of a polymer solution or more and to a softening temperature of the spinning substrate . 2. The electrospinning method according to claim 1 , wherein a spinning space between the injection part and the collector is set to room temperature.

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