JPH041084B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an upflow bath spinning method. More specifically, the present invention relates to an improved jet-type upward flow bath spinning method for producing yarn by a wet spinning method. For example, when spinning a spinning dope that can be wet-spun, such as viscose, there is
A method has been proposed that uses the jet-type upflow bath spinning method described in Japanese Patent No. 132128 to increase the spinning speed and increase productivity. However, the injection-type upflow bath spinning method described above has problems with industrial production, such as a decrease in the physical properties of the raw yarn and an increase in process defects such as yarn breakage and fuzz, which have been encountered with the conventional upflow bath spinning method. The basic problem in thinking has been solved, but there are injection types such as a coagulation bath head tank for injecting the coagulation bath from a flow tube, or a pump for pumping the coagulation bath into a coagulation bath head tank. Therefore, large-scale auxiliary equipment is required, resulting in problems such as a large investment in equipment modification or equipment construction and an increase in equipment space.
Therefore, in order to implement the injection-type upward flow bath spinning method on an industrial production scale, it has become essential to downsize and improve the efficiency of incidental equipment, but there is no method that satisfies these requirements. Not proposed so far. As a result of intensive research into this problem, the inventors of the present invention have found that by introducing a small amount of air into the flow tube for spouting the coagulation bath, the coagulation bath can be transferred to the head tank for spraying the coagulation bath from the flow tube or to the coagulation bath head tank. It is possible to significantly downsize and improve the efficiency of injection-type ancillary equipment such as pumps for pumping up water, and not only maintain good physical property levels and process performance. The yarn breakage that occurs when separating the yarn from the coagulation bath has been reduced to 1/2 of the conventional method.
The inventors have discovered that it is possible to suppress the value to 10 or less, and have completed the present invention. That is, the present invention provides an upflow bath spinning method in which a coagulation bath is intentionally spouted into the air using a flow tube.
The method is an upflow bath spinning method characterized by introducing a small amount of air into the flow tube. An example of an embodiment of the present invention is shown in FIGS. 1 to 3. The present invention will be explained in more detail with reference to FIGS. 1 to 3. FIG. 1 is an example of an embodiment of the upflow bath spinning method of the present invention. The spinning dope is introduced from the spinning dope introduction direction 1 through the spinning dope introduction tube 2, passing through the spinneret 4 attached to the spinneret support 3, and then passing through the coagulation bath introduction direction 5 in the direction of the arrow. It is discharged into the coagulation bath introduced from the direction through the coagulation bath introduction pipe 6. The latter half of the coagulation thread 7 is formed while passing through the flow tube 8 together with the coagulation bath. In the flow tube 3, from the arrow direction of the atmospheric air introduction direction 11,
An atmosphere introduction pipe 9 for introducing the atmosphere is provided,
The introduced atmosphere is adjusted to a required amount by an air introduction amount adjustment valve 10, and then passes through the flow tube 8 together with the semi-coagulated yarn 7 and the coagulation bath. After leaving the flow tube 8, the coagulation bath is blown up as a blown-up coagulation bath 12 together with the coagulated thread 13 and the introduced atmosphere, and near the apex 14 of the blown-up coagulation bath, the coagulated thread 13 is
It is separated from the blown-up coagulation bath 12 and withdrawn for post-treatment if necessary. FIG. 2 is an example of ancillary equipment for ejecting a coagulation bath from a flow tube. The coagulation bath is supplied from the main coagulation bath supply pipe 2.
1 is pumped up by a pump 22 and supplied to a coagulation bath head tank 19. In the coagulation bath head tank 19, the coagulation bath is guided through the coagulation bath introduction main pipe 17 to the coagulation bath introduction branch pipes 18 to each weight while maintaining the set head surface 20 with a weir etc., and is blown up as a coagulation bath 12. It is ejected from the flow tube 8 together with the yarn. H and _H2 are the head lengths between the head surface 20 and the apex 14 of the blown-up coagulation bath, respectively, when the outlet of the flow tube 8 is taken as the zero point. It was found that by introducing a small amount of air into the flow tube, H ₂ can be significantly increased for the same H ₁ . Originally, the coagulation bath was supplied as an incompressible continuous fluid from the head tank to the flow tube.
Due to flow resistance with the walls of parts such as joints, piping, valves, flow pipes, etc., a pressure loss corresponding to H ₁ −H ₂ =ΔH occurs. However, it is thought that by introducing a small amount of air into the flow tube, the tube wall resistance due to the viscosity of the coagulation bath inside the flow tube was pressure released and reduced. In principle, the atmosphere may not necessarily be introduced into the flow tube, but may be introduced through the flow tube support or through the coagulation bath introduction branch pipe, but in industrial implementation, it is realistically limited to the flow tube. . The reason for this is the following three points. First of all, regarding industrial production equipment,
Because it is necessary to emphasize uniformity between the weights,
It is designed to minimize the pressure drop in the piping system that introduces the coagulation bath to each spindle, and the effect of introducing atmospheric air is small in areas where the pressure drop is small.Secondly, in the case of industrial production equipment, the coagulation bath In order to reduce the proportional cost and the running energy cost of the pumping bath equipment, the diameter of the flow tube is designed to be small in order to reduce the amount of coagulation bath sprayed as much as possible. Thirdly, considering the effect on yarn quality, as is well known to those skilled in the art, disturbing the flow of the uncoagulated spinning stock solution will result in the production of the product yarn. This creates a fatal defect in the internal structure, and even if the surface solidifies and is slightly disturbed, the inside of the flow tube does not affect the internal structure, so the quality of the product yarn, that is, the level of physical properties, is not affected. , are the most suitable. According to the method of the present invention, the head length of H _{1 required to eject a predetermined amount of H 2 can} be reduced. Therefore, it is clear that the amount of bath pumped into the head tank can be reduced. This becomes even more useful when the spinning speed is increased, that is, when the coagulation bath flow rate is increased. FIG. 3 schematically shows an example of a method for introducing a small amount of atmospheric air into the flow tube of the present invention. A shows a flow tube 8 with an air introduction hole 23 bored therein, and b shows an air inlet pipe 9 attached to the air introduction hole. In addition, c represents the flow tube 8 and the flow tube support 24.
As can be seen from the vertical cross-sectional view of FIG. The sizes of the air inlet hole 23, the air inlet pipe 9, and the air inlet groove 25 should be designed in accordance with the required flow velocity in the pipe, and if they are too large, leakage of the coagulation bath will occur. Therefore, as shown in FIG. 1, it is preferable to provide a valve or a valve in the air introduction pipe 9 to adjust the amount of air introduced. Furthermore, it is more preferable that the direction of atmospheric air introduction is at an acute angle to the flow direction of the coagulation bath. This angle is shown as θ in FIG. 3b. A common example would be a glass ejector connected to tap water used in a suction experiment in science. According to the present invention, it has become possible to downsize the pumping bath equipment used in the injection type upflow bath spinning method and to reduce the amount of pumping bath. Surprisingly, there is yet another advantage that was not anticipated by the inventors. By using the flow tube of the present invention, the rate of yarn breakage that occurs when separating yarn from a coagulation bath can be suppressed to 1/10 or less of the conventional rate. Although the reason is not clear, it is understood that the occurrence of yarn breakage during yarn separation is due to the fact that the single yarns constituting the yarn are caught in the bath flow and come apart near the top of the blown-up coagulation bath. According to
Since this phenomenon of unraveling of single fibers is hardly observed, it is thought that the apparent specific gravity of the coagulating bath flow becomes smaller due to the introduction of air into the blown-up coagulation bath, and the tension of the bath flow on the single fibers decreases. It will be done. Note that the flow tube may or may not be provided at an angle with respect to the perpendicular to the ground surface. EXAMPLES Hereinafter, the effects of the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples. Example 1 Viscose with a cellulose concentration of 8.0% by weight and an alkali concentration of 5.5% by weight, produced by a conventional method, was mixed with 150 g of H ₂ SO ₄ produced by a conventional method,
A 120 denier 26 filament was spun at a spinning speed of 170 m/min according to the spinning method shown in FIG. 1 in a coagulation bath containing 280 g of Na _{2 SO} 4 and 15 g of ZnSO ₄ at 52°C. The flow tube is made of glass with an inner diameter of 9 mmφ and a length of 400 mm, tilted at 8 degrees perpendicular to the ground surface.
An air inlet tube with a hole diameter of 2 mmφ was installed 30 mm from the bottom of the flow tube, a rubber tube was attached to the tip, and the amount of air introduced was adjusted to about 100 c.c./min using pinch tips.
The amount of air introduced was measured by guiding the coagulation bath ejected from the flow tube into a sealed plastic bag and collecting it using a gas collection method. H ₁ = 400mm and H ₂ = 255mm as shown in Figure 2
It erupted. The flow velocity in the flow tube is 100 m/min, and the speed is H ₂
When I lowered H ₁ to set it to = 140mm, H ₁ = 220mm and H ₂ = 140mm. Under these conditions, the yarn was blown up and separated from the coagulation bath, passed through a yarn path and rollers, and wound into a centrifugal pot, and subjected to usual post-treatment to form a product filament. To represent the occurrence rate of yarn breakage and physical property values when separating yarn from the coagulation bath, we used a continuous strength and elongation measuring device (Type 96) manufactured by Worcester Co., Ltd.
The dry elongation of the yarn was continuously measured every 1 m over the period of time, and the average value and standard deviation value σ were calculated. The results are shown in Table 1. Comparative Example 1 The same procedure as Example 1 was carried out except that the air introduction tube was not provided in the flow tube, and H ₁ = 400 mm as shown in Fig. 2 was obtained.
H ₂ =140 mm. Under these conditions, evaluations were conducted in exactly the same manner as in Example 1. The results are shown in Table 1. Example 2 The spinning speed was set to 250 m/min, and the amount of air introduced was approximately 250 m/min.
cc/min and H ₁ = 1840 mm as shown in Figure 2, but in the same manner as in Example 1, H ₂ = 900 mm.
It became. The flow velocity in the flow tube is 180 m/min, that is, H ₂ =
When I lowered H ₁ to set it to 460mm,
H ₁ =950mm. Under these conditions, evaluations were conducted in exactly the same manner as in Example 1. The results are shown in Table 1. Comparative Example 2 The same procedure as Example 2 was carried out except that the air inlet tube was not provided in the flow tube, and H ₁ = 1840 as shown in Fig. 2 was obtained.
mm, H ₂ =460 mm. Under these conditions, evaluations were conducted in exactly the same manner as in Example 1. The results are shown in Table 1.

[Table] From the above examples and comparative examples, it is clear that the present invention can significantly reduce the size of the coagulation bath head tank compared to the conventional method, and can suppress the occurrence of yarn breakage during yarn separation to an extremely low value. Moreover, it is clear that the usefulness will increase if a good level of physical properties is maintained and the spinning speed is further increased.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an example of an embodiment of the upflow bath spinning method of the present invention. FIG. 2 is a schematic diagram showing an example of ancillary equipment for ejecting a coagulation bath from a flow tube. FIG. 3 is a schematic diagram showing an example of an embodiment of the flow tube of the present invention. a is a longitudinal sectional view of a flow tube with an air introduction hole 23, b is a longitudinal sectional view of a flow tube provided with an air introduction tube, and θ is an angle representing the direction of air introduction with respect to the flow direction of the coagulation bath. c is flow tube 8
FIG. 3 is a vertical cross-sectional view of the flow tube support 24 divided into two parts and assembled, and d is a cross-sectional view thereof. 1: Direction of spinning dope introduction, 2: Spinning dope introduction tube, 3: Spinneret support, 4: Spinneret, 5: Direction of coagulation bath introduction, 6: Coagulation bath introduction tube, 7: Semi-coagulated yarn, 8 : Flow pipe, 9: Air introduction pipe, 10: Air introduction amount adjustment valve, 11: Direction of air introduction, 12:
Sprayed coagulation bath, 13: Coagulation thread, 14: Vertex of spouted coagulation bath, 15: Inclined line of flow tube, 16: Perpendicular line to ground surface, 17: Coagulation bath introduction main pipe, 18:
Coagulation bath introduction branch pipe to each weight, 19: Coagulation bath head tank, 20: Head surface, 21: Coagulation bath supply main pipe,
22: Lifting bath pump, H ₁ , H ₂ : Head length between the head surface 20 and the blown-up coagulation bath 14 when the outlet of the flow tube 8 is taken as the 0 point, 23: Air inlet hole, 24:
Flow tube support.

Claims (1)

[Claims] 1. An upflow bath spinning method in which a coagulation bath is intentionally spouted into the air using a flow tube, which is characterized by introducing a small amount of air into the flow tube.