JPH0291206A - Dry-wet spinning process - Google Patents

Abstract

PURPOSE:To enable stabilized dry-wet spinning with increased productivity by extruding a filament yarn from a spinneret having several blocks of orifices, coagulating the yarn in a coagulation bath equipped with specific guides fixed in the bath, separating the yarn into filaments and winding up. CONSTITUTION:The spinneret orifices are arranged into 2 or more blocks so that the interval from one block to the adjacent one is made 2a or more (where a is the distance between the spinneret face and the coagulation bath surface). The spinneret is used to effect spinning of a polymer such as an acrylic copolymer in the vertical direction. The extruded filaments are introduced into the coagulation bath where the filaments are coagulated, then separated into each filament using a fixed guide in the bath, having projections of 5mm or more height, as the filament direction is changed, and wound up whereby the spinning is operated stably and yarns of uniform properties are obtained.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a dry-wet spinning method, particularly a spinning method that is advantageous for forming multiple holes and multiple threads in a static bath dry-wet spinning method for acrylic fibers. It is.

More specifically, the present invention relates to a method for stably spinning a yarn having a large total number of filaments by increasing the running stability of the yarn in a coagulation bath during dry-wet spinning.

In addition, the present invention involves spinning a plurality of multifilament yarns with a relatively small total number of filaments in a coagulation bath without mixing fibers,
The present invention also relates to a spinning method that makes it possible to obtain yarn with uniform properties.

[Prior Art] A wet spinning method is employed as a method for spinning a polymer that does not melt by heating or a polymer with an extremely high degree of polymerization into fibers. A variation of this wet spinning method is the so-called dry-wet spinning method. This is a method in which the polymer discharged from the spinneret travels through the gas and then is immediately introduced into the coagulating liquid to coagulate. However, the difference from simple wet spinning is that drafts are localized in the gas part. As a result, it has the characteristic of being capable of spinning at high speed or high draft, and is used for spinning acrylic fibers, particularly for spinning clothing filaments with a relatively small number of filaments and precursors for carbon WC textiles.

The dry-wet spinning method includes a falling bath method and a standing bath method.

The falling bath method is a spinning method in which fibers are spun while a bath liquid is flowing down, in order to improve the spinning productivity of polymers having a relatively small number of filaments.

On the other hand, the static bath method refers to a spinning method in which the coagulated filament, which normally runs in the vertical direction, is diverted using a guide and taken up, separated from the coagulation bath liquid and taken above the coagulation bath, and does not involve any special measures. However, since the liquid accompanying the coagulation bath can be efficiently separated, it is widely used, especially when the number of filaments is relatively large and spinning is performed at low speed.

In the case of a yarn with a small number of filaments in such dry-wet spinning, high productivity can be achieved by making use of the advantage of higher speed compared to wet spinning.

However, this method tends to have lower spinning tension than the wet spinning method, so for products with a large number of filaments, it is necessary to increase the spacing between the holes in the nozzle to prevent single yarns from fusing, resulting in larger equipment. There was a problem in that the flow of the coagulating liquid caused significant disturbance of the yarn, resulting in a decrease in productivity.

The following techniques are known as improved versions of these techniques.

For example, in US Pat. No. 4,702,876, it is known that a large number of threads are spun from one spinneret during falling bath dry-wet spinning of polyamide filaments. However, in the case of a flowing bath, it is necessary to connect the flow tube with an opening/closing device, etc., which makes the device complicated.

In order to prevent the spun yarn from being disturbed in the static bath dry-wet method, a belt is hung around the guide in the bath and rotates to prevent problems such as the winding of single yarns caused by the accompanying liquid flow. There is a devised structure to prevent the
Publication No. 3514).

There is also a known invention in which the bath liquid is controlled to prevent yarn disturbance (Japanese Unexamined Patent Publication No. 60-39406).

However, these ideas and inventions had the problem of complicating the device.

An example of studying the improvement of spinnerets is JP-A-63-85.
Seen in Publication No. 103. The present invention relates to a starting nozzle having a structure in which a material with good spinnability is used only on the ejection surface of the nozzle.

Furthermore, in the invention disclosed in Japanese Patent Publication No. 62-61684, a plurality of discharge holes are provided in the counterbore of one spinneret in order to increase the productivity of melt spinning. However, even if such a spinneret is directly applied to dry-wet spinning where the distance between the coagulating liquid level and the spinneret is about 10 mm or less, there are problems in that the yarns stick together and the bath liquid is disturbed.

[Problems to be Solved by the Invention] In the conventional static bath dry-wet spinning method, it is difficult to spin yarn with a particularly large number of filaments, or to spin yarn with a relatively large number of filaments and yarn with a relatively small number of filaments using the same device. When spinning using this method, there was a problem that productivity and yarn quality decreased.

Especially when spinning yarn with a large number of filaments at high speed,
Spinning at high speeds is not possible due to mixing of yarns in the coagulation bath, decreased stability of the fiber splitting state before and after the yarn running direction change guide, and generation of fuzz and yarn breakage in the spinning and drawing process. As a result, productivity had to decline, quality also deteriorated, and it was impossible to separate the fibers into multiple fibers if necessary.

An object of the present invention is to improve the productivity of wet-dry spinning using a relatively simple device. In particular, in the static bath dry-wet spinning method, the purpose is to improve the running stability of the yarn during high-speed multi-filament spinning, thereby increasing equipment productivity to an unprecedented degree.

[Means for solving the problem] The above-mentioned problem is solved by arranging the holes of the nozzle in two or more blocks in the static bath dry-wet spinning method, and setting the interval between one block and the other block to be 2a or more. At the same time, a fixed coagulation bath guide having 1 or more protrusions for fiber splitting with a protrusion height of 5 mm or more is installed in the coagulation bath almost directly under the nozzle, and a plurality of guides are installed in each block. This can be achieved by a dry-wet spinning method characterized by spinning multifilaments in the vertical direction, splitting the fibers between the protrusions of a fixed guide, and then taking them off.

Here, a is the distance between the cap and the coagulation bath liquid level at the end of the cap.

Although a varies depending on the polymer used and spinning conditions, it is usually set to 1 to 20 mm, preferably 2 to 10 mm.

The optimum distance between the blocks when the nozzle holes of the present invention are formed into blocks varies depending on the polymer used and the spinning conditions, but it is most affected by the distance a between the nozzle and the coagulating liquid level, and even if it is less than 2a. In this case, the blocked *$it and the fibers become entangled, making it impossible to separate the fibers, and the length of 60 m
If it exceeds m, the entire mouthpiece becomes large and equipment productivity decreases, which is undesirable.
m or less.

The number of holes in one block unit varies depending on the required fineness, but a value of 300H or more, preferably 500H or more and 3000H or less gives good results. The distance between the holes in the block is within 3 mm, preferably within 2 mm.0.5
Designed to be larger than mm. If the hole spacing of the spinneret becomes too small, the accompanying flow of coagulation will increase during high-speed spinning.
The liquid level in the center of the block tends to drop and the spinnability tends to decrease. On the other hand, if it is too large, the convergence angle of the yarn at the outer peripheral portion of the spinneret becomes too large, which tends to reduce spinnability.

The shape of the blocks can be - e.g. rectangular, square, circular,
It can be oval or a combination of these shapes, and is determined by the overall shape of the cap and the block spacing. Specifically, there are rectangular blocks arranged and a groove-shaped non-perforated zone with a width of 2 a or more provided at the opening, and one block arranged in a circular or oval shape, especially blocks in circular units. It is more preferable that a plurality of holes are arranged and the distance between the closest holes is 2a or more.

From the viewpoint of solvent corrosion resistance in dry-wet spinning, the spinnerets used in the present invention are made of corrosion-resistant stainless steel such as gold-platinum alloy, tantalum, hastelloy, austenitic, austenite-ferrite, or precipitation-hardened stainless steel. It is preferable to consist of the following. In order to facilitate the start of spinning, these spinnerets are preferably made of a material that has good mold release properties from the polymer, and are further preferably coated with a fluorine-based or silicone-based mold release agent.

In addition, a material with good mold releasability and corrosion resistance is used on the surface of the cap.
An inexpensive material with excellent mechanical strength may be selected as the base material, and a composite cap may be formed by coating, laminating, or other means.

The coagulation guide used in combination with the spinneret is installed vertically below the spinneret, and needs to be provided with protrusions for fiber separation that correspond to the blocks of the spinneret. In this case, the height of the protrusion is set to 5
It is characterized by being at least 10 mm, preferably at least 10 mm and at most 30 mm.

If the height of the protrusions of the coagulation guide is less than 5 mm, the line separation property will be reduced, and if the height of the protrusions is more than 30 mm, the turbulence of the coagulating liquid flow will be excessive, and the spinnability will be reduced.

If the guide of the present invention has a rotatable structure, the splitting properties will deteriorate, so it needs to be fixed.

Further, it is preferable that the guide has the effect of converging the threads. -For example, the diameter of the guide is 10 mm or less at the center between the protrusions for fiber separation, and 60 mm at both ends.
It has a rod-like structure in which rotary circular units of m or less in size are connected by protrusions for fiber separation.

When the diameter of the coagulation guide is 10 mm or more, the frictional resistance due to the guide becomes large, and the spinnability tends to deteriorate. Furthermore, if the diameter of both ends of the guide exceeds 60 mm, turbulence in the flow of the coagulating liquid is amplified, which tends to cause a decrease in spinnability.

The surface of this guide is generally made of metals such as chrome plating, ceramics such as alumina, titanium, and high-performance glass, and plastics such as nylon, phenolic resin, and fluorine resin, and the surface prevents the thread from being scratched. In order to achieve this, the friction force must be small and the surface must have a smooth finish.

The method for spinning yarn from each block varies depending on the required fineness of the yarn, etc., but in the present invention, single yarns from at least one or two or more blocks are collected and multiple yarns are spun vertically. After spinning in the same direction and coagulating at least the surface layer, it is necessary to separate the fibers using a coagulation guide, change the direction, and take it off. In this case, it is possible to take yarns from multiple blocks into the same coagulation guide part, and the yarns coming out of the guide may be combined, but from the viewpoint of yarn stability, one or It is preferable to bundle the single filaments from two blocks, take them off at the same part of the coagulation guide, maintain the divided state even after changing the direction with the guide, and take them out of the coagulation bath.

There is no particular restriction on the shape of the coagulation bath, but in order to prevent disturbance of the liquid bath, the liquid surface around the nozzle is covered with porous metal, #50~5.
It is preferable to protect it with a 00 mesh wire mesh or the like.

The polymer applied to the present invention is not particularly limited as long as it can be spun by wet spinning, but when applied to polyacrylonitrile, which is an acrylic polymer containing 90% or more of acrylonitrile as a monomer, spinnability is Effective for improvement. It is especially effective when used in the production of acrylonitrile* fibers for carbon fiber applications, which require high-quality yarn with little fuzz.

The present invention will be explained in detail below with reference to Examples.

[Example] Example 1 An acrylic copolymer was once extruded into the air from a die, then introduced into a coagulation bath and coagulated, and the yarn was placed at a depth of 500 mm in the bath.
The bow was turned and harvested using a folded guide located at mm.

Here, adjust the height of the cap so that the distance a between the cap and the coagulating liquid level is 4 mm, and the total number of holes for the cap is 4500H.
The hole spacing was 1 mm. Further, as the solidification direction changing guide, one with a protrusion of 20 mm in height and one without a protrusion were used. In each case, 4,500 filaments were withdrawn from the coagulation bath and supplied to the subsequent process.

Limit spinning speed under each condition and spinning speed 15m,
Table 1 shows the yarn quality at /rnin.

(Left below) Table 1: 25 m/m under conditions within the scope of the present invention (No, 5.7)
In contrast, there are those that do not have a splitting protrusion on the guide and are spun as a single thread (No. 1-3), those that are not divided into blocks, and those that are not divided into blocks. If the block spacing is narrow (No. 4.6), the spinnability decreases.

Example 2 An acrylic copolymer was once extruded from a die into an air space set to a thickness of 3 mm, and then introduced into a coagulation bath, and the coagulated thread was turned around using a folding guide and taken off.

Here, a cap with a total number of holes of 1000H and two circular blocks of 500H each was used. Also, a guide having a protrusion for separating fibers of different heights in the center was used.

In order to compare the spinning stability, continuous spinning was performed for 24 hours, and the following two items were evaluated.

A. Fiber mixing A fixed guide with a protrusion height of 12 mm was used to change the block interval of the nozzle, and the disorder of the yarn was observed between the coagulation guide and the nozzle.

B1 Fibrillation property The groove interval of the spinneret was maintained at 10 mm, the height of the protrusion of the coagulation bath guide was varied, and the number of times the yarn moved over the guide protrusion and merged with the adjacent yarn was observed.

The results are shown in Table 2.3. Those where the block spacing is less than 2a (in this case 6mm) or the height of the protrusion is 5mm
It can be seen that the spinnability is poor when a guide of less than

Table 2 Table 3 [Effects of the Invention] According to the static bath dry-wet spinning method of the present invention, stable spinning can be performed at a relatively high speed. Furthermore, it becomes possible to spin yarns with a large number of filaments and yarns with a small number of filaments with high productivity using the same spinning machine.

Claims (1)

[Claims] In the static bath dry-wet spinning method, the holes of the spinneret are arranged in blocks of two or more, the interval between one block and the other block is 2a or more, and the holes almost directly under the spinneret are arranged in blocks. One or more protrusions with a height of 5 mm in the coagulation bath
A fixed coagulation bath guide having the protrusions for fiber splitting as described above is provided, a plurality of multifilaments are vertically spun in blocks, and the fibers are split between the protrusions of the fixed guide.
A wet-dry spinning method characterized by pulling. Here, a is the distance between the cap and the coagulation bath liquid level at the end of the cap.