JPS6353281B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrospinning apparatus. The purpose of this invention is to provide a spinning device for influencing the molecular orientation of a spun yarn using an electric field to obtain fibers with controlled orientation.

Conventionally, the conventional method for manufacturing man-made fibers is to first obtain undrawn yarn with little molecular orientation in the spinning process, and then draw and heat treat the undrawn yarn to orient and crystallize it. It is being
In recent years, a method has been developed in which spinning is performed at a relatively high spinning speed of 3000 to 4000 m/min to obtain partially oriented yarn (POY) in which the molecules are oriented to some extent, and then a slight stretching and false twisting are performed simultaneously ( POY−DTY
processing methods) are beginning to be used. More recently, research has been carried out on ultra-high speed spinning to obtain highly oriented yarns in one step without drawing. However, in this method, although the overall orientation of the molecules reaches a considerable level, the disorder of the molecules in the amorphous portion is greater than in the fiber obtained by drawing conventional undrawn yarn. I have come to understand this.

On the other hand, the so-called zone drawing method, in which fibers obtained by conventional spinning methods are rapidly heated and cooled while applying high tension, and the zone heat treatment, in which the fibers are subsequently heat-treated while applying high tension, are used to develop polymers. High elastic modulus consisting of extended chain crystal structure,
There is an idea to obtain high-strength fibers (for example, Journal of the Japan Institute of Fiber Science, Vol. 38, No. 6, p. 257 (1982)).

However, in this method, the molten polymer flow is cooled and turned into fibers, and not only is it not an energy-saving method in that it is heated and cooled again, but also the fibers obtained by such zone drawing and zone heat treatment methods are The physical properties are limited in that they depend on the orientation state of the raw fibers at the initial spinning stage.

Controlling the molecular orientation of spun yarn in this way has become an extremely important technology. On the other hand, research has also been conducted in which the spinneret is used as one electrode, a counter electrode is provided below the spinneret, and a high voltage is applied between them for spinning (e.g., Journal of Polymer Science, Polymer Physics Edition). (Polym.Phys.Ed. Vol. 19, p. 909 (1981)). This method applies an electric field to the yarn being spun during spinning, but a voltage is applied between the spinneret and its opposite pole. Because of this, a complicated structure must be adopted to insulate the spinning pack from the main body, which is not only unsuitable for industrial implementation, but also because the electric field is Because of this, even if the molecules are once oriented, they return to a disordered state, making it difficult to control the molecular orientation of the spun yarn.

The present inventors have repeatedly studied a device that controls molecular orientation by applying an electric field to the spun yarn, and found that the device can be simplified by providing the electric field generator separately from the spinneret. Moreover, the present invention was achieved by discovering that the molecular orientation can be easily controlled.

That is, the present invention provides a direct current electric field generating device that generates electric lines of force in a direction substantially parallel to the spun yarn between the spinneret and the winding device and is separated from the spinneret. This is an electrospinning device characterized by:

Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 1 shows an example of the apparatus of the present invention used during melt spinning, in which 1 is a spinneret, 2 is a DC electric field generator, 3 and 3' are take-up godet rollers,
4 is a winding device. The yarn Y melted and discharged from the spinneret is transported by take-up godet rollers 3 and 3'.
The yarn is taken up at a constant spinning speed and wound up by a winding device 4. With respect to the spun yarn Y, substantially parallel electric lines of force are generated by a DC electric field generating device 2 provided directly below the spinneret 1. The DC electric field generator 2 is
A pair of electrodes 5, 5', an insulator 6 that supports the electrodes,
A chamber 7 formed by the electrodes 5, 5' and the insulator 6 is filled with gas to prevent corona discharge. As the corona discharge prevention gas, sulfur hexafluoride, nitrogen, etc. are used, but in the case of low voltage, air may also be used. 8 is an inlet for a gas for preventing corona discharge, and 9 is a DC power source. The electrodes 5, 5' usually have a thread passage 10,
A disc-shaped material having a diameter of 10' is used, and its material is preferably copper, aluminum, brass, stainless steel, etc., and in particular, one with a low content of impurities is preferred. The shape of the electrodes 5 and 5' is preferably flat as much as possible to prevent local electric field concentration since high voltage is applied, but depending on the case, it may be shaped like a donut, a hollow cylinder, or a hollow truncated cone. It can be anything. In order to maximize the strength of the electric field applied to the spun yarn Y, the yarn paths 10 and 10' are desirably made as small as possible within a range where the spun yarn Y does not come into contact with them.

The DC electric field generator 2 needs to be provided separately from the spinneret 1. If the spinneret is used as one electrode and a voltage is applied between it and the opposite electrode, it is necessary to use an extremely complicated structure to insulate the spinneret, which is not suitable for industrial implementation. In addition, in such a device, the electric field is applied immediately after spinning when the molecules are in a state of extremely strong motion, so even if the molecules are once oriented, they return to the disordered state, making it difficult to control the orientation of the spun yarn. It becomes difficult to do so. The position where the DC electric field generator 2 is installed is such that the thinning phenomenon progresses until the solidification of the spun yarn Y is completed, that is, when the crystallization rate of the spun yarn Y is sufficiently slow and the thinning phenomenon progresses at a high temperature. It is most preferable that the area is located between the spinneret 1 and the winding device 4, but it is not limited to this particular position, and can be provided at any position between the spinneret 1 and the winding device 4. However, even if an electric field is applied in a completely cooled and solidified state, it is difficult to control the molecular orientation, so it is best to apply an electric field while the temperature of the spun yarn Y is high and the molecules are easily mobile. It is important to do so. In the case of melt spinning, it is preferable to provide the DC electric field generator 2 at a distance of 60 to 150 cm from the spinneret 1. Note that the winding device in the present invention is not limited to a winder, but also includes collecting devices such as cans and nets.

The apparatus of the present invention can be applied not only to melt spinning but also to dry spinning. In both dry spinning and wet spinning, the installation position of the DC electric field generator must be set until the solidification of the spun yarn is completed, that is, when the remaining amount of solvent coexisting with the spun yarn is 5% or more. Area where the thinning phenomenon is progressing (1 to 2 m from the spinneret)
Although it is most preferable that the fibers are separated from each other, it is not particularly limited to this position, as in the case of melt spinning.

The DC electric field generating device is installed so that the direction of the generated electric lines of force is substantially parallel to the spun yarn. Here, "almost parallel" means that the angle between the direction of the electric lines of force (vector of the electric field) and the spun yarn is 45
It means less than 30 degrees, especially preferably 30 degrees or less. Further, the direction in which the electric field is applied may be the same as the traveling direction of the spun yarn, or may be the opposite direction.

FIG. 2 shows various embodiments of the DC electric field generator in the apparatus of the present invention.

First, the correlation between the traveling direction of the spun yarn Y and the vector direction of the electric field (indicated by the dotted line in the figure) generated between the pair of electrodes 5 and 5' of the DC electric field generator 2 is shown in Figure 2a. As shown in b, the DC power source 9 may generate electric lines of force in the same direction as the traveling direction of the spun yarn Y, and as shown in b, the DC power source 9' may generate electric lines of force in the opposite direction to the traveling direction of the spun yarn Y. In some cases, lines of force may be generated, and as shown in c, any angle θ between the running direction of the spun yarn Y and the direction of the electric lines of force is less than 45 degrees.
In some cases, it is tilted so as to form a shape. All of these fall within the category of "generating lines of electric force in a direction substantially parallel to the spun yarn." These DC electric field generators can be used in various combinations, and d, e are a, b,
This shows examples of various combinations of c.

FIG. 3 shows an example of the relationship between electric field strength and time. The strength of the electric field in the yarn path of the DC electric field generator may be always constant as shown in Part 3 a, or may vary over time as shown in part b. Furthermore, the way the electric field changes may take a step-like value as shown in c.

The direction of the lines of electric force in the electric field (vector direction of the electric field) and the strength of the electric field are arbitrarily selected and used depending on the purpose of controlling the molecular orientation of the spun yarn.

Although the above example has been explained using a monofilament, the invention can be similarly applied to a multifilament. FIG. 4 is a schematic cross-sectional view in this case, and 1
2 is a spinneret, 13 and 13' are godet rollers,
14 is a winding device. Reference numeral 20 denotes a DC electric field generator, which is provided directly below the spinneret 12. The DC electric field generator 20 includes a pair of plate-shaped electrodes 21, 2.
1'. These electrodes 21, 21' have through holes 22, 2 that correspond approximately to the discharge holes of the spinneret 12.
2' is perforated.

The through holes 22, 22' are larger than the discharge holes so that the filament yarns Y do not come into contact with each other when the filament yarns are bundled during winding. The electrodes 21, 21' are formed by protrusions 23 provided on the outer periphery of grooves 26 carved in a cylindrical insulator 25.
are engaged with each other and are connected via a connecting rod 24 to an elevator 27 disposed outside the insulator 25.
At the start of spinning, the elevator 27 is activated, that is, the electrode 21' first rises to the position of the electrode 21 and comes into contact with it, and then engages with this electrode 21 and rises as one to the position of the spinneret 12, and the 12.

In this state, the polymer is discharged and taken up, and after a normal state is reached, the elevator 27 is operated to return it to its original position as shown in the figure. At the upper and lower ends of the insulator 25, horizontally opening type shutters 28, 28' are provided, which are divided into two, and a chamber 29 is formed between them. 30 is an inlet for corona discharge prevention gas, and 31 is a DC power source.

In the DC electric field generator in the device of the present invention, the strength of the electric field applied to the spun yarn is preferably about 1 KV/cm or more, preferably 5 KV/cm or more, and about 50 KV/cm or more. It is preferable to apply a strong electric field. The strength of the electric field applied to the spun yarn should be greater when applied to melt spinning than in dry spinning and wet spinning, where the viscosity of the polymer solution is relatively low due to the use of a solvent. is preferred.
However, the optimum value of the electric field strength varies depending on the type of polymer to be spun, the type of solvent used, the spinning temperature, etc.

The spinning device of the present invention may be a normal spinning device that winds the yarn discharged from the spinneret by traveling in the direction of gravity, that is, from top to bottom, or vice versa. From the spinneret installed below,
It may be a spinning device that takes the spun yarn upward. Furthermore, a spinning device may be used which allows the spun yarn from the spinneret to travel in the horizontal direction and be taken up.

The spinning apparatus of the present invention can also be applied to conjugate spinning, mixed spinning, etc. It is also applicable to melt blow spinning and jet spinning, which are one form of melt spinning. Furthermore, it is also applicable to the flash spinning method in dry spinning. It can also be applied to spinning yarns with irregular cross sections, hollow cross sections, and the like.

In the spinning device of the present invention, it is also possible to use the DC electric field generator in combination with other energy adding devices or fiber processing devices.
For example, as another energy adding means, a magnetic field generator made of a superconducting magnet or the like may be used in conjunction with the device of the present invention before or after the DC electric field generator to more reliably control the molecular orientation of the spun yarn. , can be made valid. Further, as the energy adding means, irradiation devices such as ultrasonic waves, microwaves, infrared rays, ultraviolet rays, and ionizing radiation can be used in combination. Furthermore, it is also possible to form fibers by combining various fiber processing means such as an interlacing nozzle or a crimping device next to the DC electric field generating device.

As explained above, the spinning device of the present invention generates electric lines of force in a direction substantially parallel to the spun yarn between the spinneret and the winding device, and is separated from the spinneret. Since a DC electric field generating device is provided, the molecular orientation of the spun yarn can be controlled extremely easily without complicating the spinning device.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram schematically showing an example of the device of the present invention, FIG. 2 is a sectional view showing various embodiments of the DC electric field generating device used in the device of the present invention, and FIG. 3 is a schematic diagram showing an example of the device of the present invention. FIG. 4 is a graph showing the relationship between electric field strength and time in the DC electric field generator used, and FIG. 4 is a schematic cross-sectional view showing an embodiment for multifilament. 1... Spinneret, 2 , 20... DC electric field generator, 4... Winding device, Y... Spun yarn.

Claims (1)

[Scope of Claims] 1. A DC electric field generating device is provided between the spinneret and the winding device, which generates electric lines of force in a direction substantially parallel to the spun yarn, and is separated from the spinneret. An electrospinning device characterized by: 2. The electrospinning device according to claim 1, wherein the electric field generating device has an electric field strength of 1 KV/cm or more. 3. The electrospinning device according to claim 1, wherein the distance between the electrodes of the electric field generating device is 30 cm or less.