JPH0770820A - Method for producing polyester fiber - Google Patents

Abstract

(57) [Summary] [Purpose] In the direct spinning and drawing method of polyester, by preventing the turbulence of the air flow generated near the inlet of the tubular heating device,
It suppresses yarn swaying and improves U%, uneven dyeing and process tone. [Structure] After polyester is melt-spun and the spun yarn is once cooled, it is continuously heated in a cylindrical heating device 6 in a non-focused state, and drawn and drawn at a speed of 3,000 m / min or more. At this time, a protective cylinder 10 that expands upward is provided above the cylindrical heating device 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyester fiber, and more specifically, a method for producing a polyester fiber in which polyester is melt-spun, cooled once, and then heated in a non-focused state and drawn at a high speed. Regarding the method.

[0002]

2. Description of the Related Art A method for producing a polyester fiber having a strength and elongation that can be put to practical use by a spinning process alone is
An ultrahigh-speed spinning method of drawing at a high speed of 000 m / min or more is known (for example, Japanese Patent Publication No. 60-47928).

However, such a high-speed spinning method has drawbacks in that workability during yarn hooking and spinning breakage is poor, and the cost of equipment such as a high-speed winder is high. Further, with such a high-speed spinning method, although it is possible to obtain a fiber with a high elongation that can be put to practical use, as a woven fabric in the actual market, tension and waist are insufficient, and spinning is performed at a low speed. Sufficient properties have not been achieved compared to fibers obtained by a separate drawing method in which the material is once wound and then stretched in a separate step, or after a fiber is obtained by a straight drawing method in which the material is continuously drawn without winding after winding .

On the other hand, as a method for obtaining polyester fibers that can be put to practical use at a spinning take-up speed of about 3,000 to 6,000 m / min, as shown in FIG. 4, a spinneret 1 and spin take-up rollers 2, 3 are provided. A cooling tube 4 and a heating device 6 having a heater 5 are provided between the cooling tube 4 and the polyester yarn Y melted and discharged from the spinneret 1, and the heating device 6 is continuously cooled.
Various so-called direct spinning and drawing methods have been studied, in which the film is heated and drawn while running inside, and then taken up by the take-up rollers 2 and 3 and wound on a winder 7. In FIG. 4, 8 is an oil agent applying device, and 9 is an interlacing device, both of which are devices for imparting the focusing property to the yarn after the direct spin drawing.

In such a direct spinning and drawing method, since the yarn heated in the heating device 6 is subjected to the drawing action by the spinning tension, the polyester fiber having the mechanical characteristics that can be put to practical use even at a relatively low take-up speed. Can be obtained. However, if the spinning tension in the heating device 6 is too low,
Since the uniform heating and drawing is not applied, the yarn shake becomes large,
The fineness unevenness (hereinafter referred to as U%) becomes large, the dyeing unevenness deteriorates, and the mechanical properties such as strength and elongation become insufficient. Therefore, further practical operations such as stretching are required for practical use. Become. On the other hand, if the spinning tension is too high, single fiber breakage, spinning yarn breakage, etc. occur frequently, and more than necessary tension is applied to the single fiber, which also causes an increase in U%.

Therefore, a method of uniformly controlling the spinning tension in the heating device 6 has been proposed (for example, Japanese Patent Publication No. Sho 5).
9-51603 and JP-A-62-162015). However, with these methods, fibrous spots, U%
Cannot be improved to a satisfactory level, and moreover, single fiber breaks and spinning breaks still occur frequently. As described above, it is considered that the reason why the method of controlling the spinning tension cannot solve the problem is that the yarn is swaying due to the air flow accompanying the yarn running at high speed.

On the other hand, in the direct spinning and drawing method, the temperature of the heating device is lowered and fluctuated by the low temperature air flowing into the heating device along with the yarn running at a high speed, and the thermal efficiency of the heating device is deteriorated. In order to prevent this, a device for preventing the accompanying air current of the traveling yarn from flowing into the heating device has also been proposed (JP-A-54-138613 and JP-A-62-69).
No. 815).

However, all of these devices are intended to prevent the entrained airflow of the traveling yarns from flowing into the heating device, resulting in temperature fluctuations and reduction in energy efficiency. It does not attempt to solve the problem caused by yarn sway caused by the accompanying air flow of the traveling yarn. Therefore, even when these devices are used, in the direct spinning and drawing method, the yarn sway caused by the accompanying air current of the traveling yarn is prevented, U% and dye spots are reduced, and single fiber breakage and spinning yarn breakage (spinning process) are performed. It is difficult to improve the condition.

Further, in JP-A-4-263608, a filament having high homogeneity is obtained by using a heating device in which the internal cross-sectional area is continuously reduced at least at the lower part in the direct spinning drawing method. It is described to obtain. It is unclear why the homogeneity of the filament is improved by using this heating device, but at least it is ineffective against the yarn sway caused by the accompanying air current of the traveling yarn, and is caused by the yarn sway. It is not possible to improve U%, uneven dyeing, and deterioration of spinning process condition. Moreover,
Equipment cost is reduced because a heating device with a special shape is used.
There is also the problem of becoming expensive.

[0010]

DISCLOSURE OF THE INVENTION The inventors of the present invention have found that in the direct spinning and drawing method, U% is increased and dye spots are deteriorated.
We have found that the frequent occurrence of single fiber breaks and spinning breaks deteriorates the spinning process. In order to minimize the effect of the above, it is necessary to provide a protective cylinder that expands upward at the upper part of the cylindrical heating device, and has completed the present invention.

That is, according to the present invention, (1) polyester is melt-spun, the spun yarn is once cooled, and then continuously heated in a cylindrical heating device in a non-focus state to obtain 3,000 m / m. A method for producing a polyester fiber, characterized in that a protective cylinder that expands upward is provided in the upper part of the cylindrical heating device when the fiber is drawn and drawn at a speed of not less than a minute, and (2) the expansion angle of the protective cylinder is The method for producing a polyester fiber according to the above (1), which is 10 to 45 degrees, (3) the length of the tubular heating device is 5
0-150 cm, the internal atmospheric temperature is 150-250
(1) where the temperature of the protective cylinder is 10 to 50 cm.
Alternatively, the method for producing polyester fiber according to (2), and (4) the plurality of spun yarns are respectively heated and drawn in a plurality of tubular heating devices that are continuously provided, and provided on top of each tubular heating device. The method for producing a polyester fiber according to (1), (2) or (3) above, wherein the upper portions of the protective cylinders are brought into close contact with the upper portions of the adjacent protective cylinders so as not to form a gap.

In the present invention, the polyester fiber means
The main target is polyethylene terephthalate, but copolyesters in which 85 mol% or more, preferably 95% or more of the repeating units are ethylene terephthalate, or these polyesters with other polymers such as polyhexamethylene terephthalate, nylon-6, It may be a blend of a small amount of nylon-6,6, polyethylene-2,6-naphthalate, polycarbonate, polymethylmethacrylate and the like.

These polyesters are known additives,
For example, pigments, dyes, matting agents, anti-dye agents, fluorescent whitening agents, flame retardants, stabilizers, UV absorbers, lubricants and the like may be included. Intrinsic viscosity of polyester fiber used in the present invention IV
(Calculated using 35 ° C o-chlorophenol solution)
Is proper in the range of 0.3 to 1.0, especially 0.5 to 0.8.

The above polyester can be directly spun and drawn by, for example, the apparatus shown in FIG. In FIG. 1, 1 is a spinneret, 2 and 3 are spin take-up rollers, and a cooling tube 4 is provided between the spinneret 1 and the spin take-up rollers 2 and 3.
And a tubular heating device 6 having a heater 5 are provided. Further, 7 is a winder for winding the yarn Y, 8 is an oil applying device, and 9 is an interlacing device. Cylindrical heating device 6
A protective cylinder 10 that expands upward is provided on the upper part of the. Reference numeral 11 denotes a shutter provided in the lower portion of the tubular heating device in order to prevent a decrease in thermal efficiency of the tubular heating device.

First, the above polyester is melted (Tm)
It is melted at a temperature of (Tm + 50 ° C.) and spun from the spinneret 1. As the spinneret 1, it is ideal that the spinning holes are arranged in one line on the circumference, which is ideal for evenly cooling the spun yarn. They may be arranged or arranged in a grid pattern.

The yarn Y spun from the spinneret 1 is once cooled by a cooling cylinder 4. If the spun yarn Y is insufficiently cooled, it will be difficult to uniformly perform the subsequent heating and drawing in the tubular heating device 6, and the homogeneity of the obtained polyester fiber will be poor. Immediately before the yarn inlet of the cylindrical heating device 6, the yarn Y is desirably cooled to the glass transition temperature or lower.

The gas blowing length of the cooling cylinder 4 is preferably about 30 to 100 cm, especially about 60 to 100 cm when the single fiber denier is 1 to 3 denier, and the spun yarn in a non-bundle state is preferable. A cooling gas of about 25 ° C. is blown toward the center of the strip Y from the lateral direction or the periphery to forcibly cool.

Next, the yarn Y thus cooled is continuously heated in the cylindrical heating device 6 in a non-focused state,
Spinning take-up rollers 2, 3 at a speed of 3,000 m / min or more
And draw and stretch. The cylindrical heating device 6 has a length of 5
0-150 cm, the internal atmospheric temperature is 150-200
It is desirable that the temperature is ° C. If the ambient temperature is too low, the stretching effect due to the temperature gradient in the tubular heating device 6 becomes insufficient, stains in an unstretched state occur, U% increases, and the structure does not stabilize and the shrinkage ratio is high. Becomes higher. On the other hand, if the ambient temperature is too high, mechanical properties such as strength and elongation are remarkably improved, but spun yarn and fusion between single fibers occur frequently, and moreover, the yarn shakes in the tubular heating device 6. Getting bigger, U
%, The stain is worse.

As the cylindrical heating device 6, a cylindrical heating cylinder is usually used, but it is not particularly limited to a cylindrical shape, and a cylindrical body of any shape is used. As the heating means of the tubular heating device 6, as shown in FIG. 1, a heater 5 may be provided internally, or heated air, steam or the like may be blown therein. Further, in order to improve the productivity, in the case of processing with two or more weights, if the heating medium heating method is adopted, the temperature difference between the weights can be reduced,
It is preferable because it is possible to eliminate the difference in the physical properties of the obtained polyester fiber, the unevenness in dyeing, and the like.

The take-up speed needs to be 3,000 m / min or more. If it is less than 3,000 m / min, the physical properties such as the strength and elongation and Young's modulus are insufficient, and when the fabric is woven, it is stretched. , It becomes a woven fabric without waist. On the other hand, if the take-up speed is too high, crystallization proceeds to a high degree, not only does the woven fabric have a paper-like feel, but also the number of spun yarns and single fiber breaks increases, and the workability deteriorates. Is 4,500 to 5,500 m / min.

Further, in the present invention, the tubular heating device 6
The protective cylinder 10 that expands upward is provided on the upper part of the. In the conventional direct spinning drawing method, the present inventors
In the process of investigating the cause of the deterioration of process condition, smoke test to observe the air flow using stannic chloride that smokes due to the reaction with moisture in the air and 1 cm × 1 cm paper pieces are arranged at 5 cm intervals. The air flow around the running yarn from the spinneret to the tubular heating device was examined by both paper strip tests that visually observe the air flow.

As a result, as shown in FIG. 4, in the vicinity of the inlet of the tubular heating device 6, the ascending airflow a heated and rising in the tubular heating device 6 and the accompanying airflow accompanying the traveling yarn Y. b
It was discovered that and collided with each other, causing turbulence in the air flow.
The turbulence of the air flow at the inlet of the tubular heating device 6 increases the yarn sway of the yarn Y, which deteriorates the U%, the uneven dyeing, and the process condition. However, in the vicinity of the inlet of the tubular heating device 6, Since there is a drawing point when the once-cooled yarn is drawn, the influence of turbulence of the air flow on U% and the like is further increased. Furthermore, in the case of direct spinning and drawing with multiple spindles of two or more spindles, the turbulence of air generated at the inlet of the tubular heating device is
As a result, it spreads to the inlet of the adjacent tubular heating device and further amplifies the turbulence of the air flow caused by the collision of the ascending air flow and the accompanying air flow.

In view of this, in the present invention, a protective cylinder 10 that expands upward is provided at the upper part of the tubular heating device 6 so that the accompanying air stream of the traveling yarn Y smoothly moves together with the traveling yarn Y. It is taken into the inside of the tubular heating device 6 so that the air flow is not disturbed due to the collision with the ascending air flow in the vicinity of the inlet of the tubular heating device 6. The protective cylinder 10 has a shape that expands upward, for example, a truncated conical shape, but the upper part may have a partially cylindrical shape. The shape is not limited to the conical shape, and may be a polygonal pyramid or the like. Further, the expansion angle of the protective cylinder 10 (angle θ formed by the expansion part with respect to the vertical direction in FIG. 1) is preferably 10 to 45 degrees, particularly preferably 10 degrees, in order to achieve the effect of the present invention. ~ 30 degrees.

The length of the protective cylinder 10 is preferably 10 to 50 cm, particularly 10 to 30 cm. If this length is too short, it is difficult to sufficiently eliminate the interference between the rising airflow from the tubular heating device 6 and the accompanying airflow of the yarn Y. On the other hand, if it is too long, the spinning tension becomes too high and the spinning breakage occurs. This leads to an increase in threads and stains.

Further, as shown in FIG. 2, after the yarns Y and Y'spun from the plurality of spinnerets 1 and 1'are cooled by the cooling cylinder 4, a plurality of continuous cylindrical heating devices 6 are provided. , 6 ', respectively, the upper part 10a of the protective tube 10 provided on the upper part of the tubular heating device 6 is replaced with the upper part 10a of the adjacent protective tube 10' provided on the upper part of the tubular heating device 6 '. It is preferable that they are in close contact with each other so that no gap is formed between them.

For example, in the case of using a truncated truncated cone-shaped protective cylinder, even if the upper parts adjacent to each other are brought into close contact with each other, the upper parts of the protective cylinder are contacted at only one point, so that a gap is formed therebetween. Therefore, as shown in FIG.
Cover the gap created between the upper parts 10a and 10a 'of 0'
Block at 2. If there is a gap between the upper portions 10a and 10a 'of the protection cylinders 10 and 10' that are adjacent to each other, the rate at which the accompanying flow of the spun yarn Y escapes to the outside of the tubular heating devices 6 and 6'is large, and It affects the weight and tends to worsen U%, stain spots and the like.

In FIG. 1, the shutter 11 provided at the lower portion of the tubular heating device 6 does not have to be provided in particular, but in order to prevent temperature fluctuations in the tubular heating device 6 and deterioration of thermal efficiency, It is preferable to provide a variable aperture shutter capable of changing the exit area of the linear heating device 6.

[0028]

EXAMPLES The present invention will be described more specifically below with reference to Examples and Comparative Examples. In addition, the physical properties of the yarn, the turbulence of air and the process tone in Examples and Comparative Examples were measured, judged, and comprehensively judged as follows. (1) Strength and elongation, 10% stress It was determined from the load elongation curve obtained using a Tensilon tensile tester. (2) U% Half-measured using a Worcester yarn spot tester manufactured by SEIKI KOGYO Co., Ltd.
An inert test was performed and the value was determined by an integrator. (3) Dye spots The knitted knitted sample was dyed and visually evaluated 1 to 5 points. The higher the score, the less the uneven stain. (4) Turbulence of airflow Turbulence of the airflow in the vicinity of the inlet of the tubular heating device during direct spinning and drawing was visually or video-observed by a smoke test and a paper piece test, and evaluated according to the following criteria. ◎ There is no turbulence in the air flow and no yarn sway. ○ There is almost no turbulence in the air flow, and there is little yarn sway. △ Turbulence of the air flow was observed, and the yarn sways greatly. × The turbulence of the air flow is extremely large, and the yarn shakes violently. (5) Process Condition The number of spinning breaks per spindle per day was measured and evaluated according to the following criteria. ◎ Less than 0.5 times ○ 0.5 times or more but less than 1.0 times △ 1.0 times or more but less than 2.0 times × 2.0 times or more (6) Overall judgment Check the above-mentioned physical properties of the yarn, turbulence of air and process condition. Overall, it was determined as follows. ◎ Extremely good ○ Good △ Somewhat bad × Bad

Examples 1 to 3 and Comparative Examples 1 to 3 Polyethylene terephthalate having an intrinsic viscosity of 0.64 and containing 0.3% by weight of titanium oxide was melted at 295 ° C., and a table shown in FIG. Direct spinning was conducted under the conditions shown in 1 to obtain a polyester filament of 75 denier.

[0030]

[Table 1]

The inlet diameter of the cylindrical heating device 6 is 35 m.
m, the length was 120 cm, the temperature was 200 ° C., the length of the protective cylinder 10 was 30 cm, and the expansion angle θ was 25 degrees. The yarn physical properties of the obtained polyester filament are as shown in Table 2, and the turbulence of the air flow near the inlet of the tubular heating device 6 during the direct spinning and drawing, the process condition and the overall judgment are as shown in Table 3. It was

[0032]

[Table 2]

[0033]

[Table 3]

As is clear from these results, according to the method of the present invention in which the protective cylinder is provided, the turbulence of the air flow is small,
The yarn physical properties, U%, uneven dyeing, and process tone are all good.

Examples 4 to 13 Polyester filaments were obtained in the same manner as in Example 3, except that the length of the protective cylinder and the expansion angle were changed as shown in Table 4 and other conditions were the same as in Example 3.

[0036]

[Table 4]

The results are shown in Tables 5 and 6, and it is particularly preferable that the length of the protective cylinder is 10 to 50 cm and the expansion angle is 10 to 45 degrees.

[0038]

[Table 5]

[0039]

[Table 6]

Examples 14 and 15 In Example 3, six tubular heating devices 6 were arranged in series, and direct spinning and drawing were carried out with 6 weights. At that time, as shown in FIGS.
In the case where a'is brought into close contact with each other so as not to form a gap (Example 14), adjacent protective cylinders 10, 10 'are used.
The upper parts 10a and 10a 'of the above are separated from each other, and a gap of 1 cm is left between them (Example 15). The results are shown in Tables 6 and 7, and when no gap was formed between the protective cylinders adjacent to each other (Example 1
In 4), the turbulence of the air flow was smaller than in the case where the gap was left (Example 15), and the U% and the stain unevenness were also excellent.

[0041]

[Table 7]

[0042]

[Table 8]

Comparative Example 4 In Comparative Example 3, the cylindrical heating device 6 was replaced by Japanese Patent Laid-Open No.
-263608 A heating device whose internal cross-sectional area continuously decreases from the inlet to the outlet (inlet diameter 45 mm, outlet diameter 30 mm, length 120 cm)
Was used, the turbulence of the air flow at the inlet of the heating device was large, and yarn sway occurred, U% was 0.70, and spots were 3.
0, the process condition was Δ, and the overall judgment was Δ.

[0044]

According to the present invention, in the direct spinning drawing, the turbulence of the air flow generated near the inlet of the tubular heating device is prevented, the yarn oscillation is suppressed, the deterioration of the process tone is prevented, and the U% is small. It is possible to produce a polyester fiber with less uneven dyeing.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an apparatus for carrying out the present invention.

FIG. 2 is a side view showing an example of an apparatus for carrying out the present invention with a plurality of cones.

FIG. 3 is a plan view of the protective cylinder shown in FIG.

FIG. 4 is a sectional view showing an example of an apparatus for carrying out a conventional method.

[Explanation of symbols]

 1, 1'Spinneret 2, 3 Spin take-up roller 4 Cooling tube 6, 6'Cylindrical heating device 10, 10 'Protective tube 10a, 10a' Upper protective tube

Claims (4)

[Claims] 1. A polyester is melt-spun, a spun yarn is once cooled, then continuously heated in a cylindrical heating device in a non-focused state, and drawn at a speed of 3,000 m / min or more. In doing so, a method for producing a polyester fiber, characterized in that a protective tube that expands upward is provided on the upper part of the tubular heating device. 2. The method for producing a polyester fiber according to claim 1, wherein the expansion angle of the protective cylinder is 10 to 45 degrees. 3. The cylindrical heating device has a length of 50 to 150 c.
The method for producing polyester fiber according to claim 1 or 2, wherein m, the internal atmosphere temperature is 150 to 250 ° C, and the length of the protective cylinder is 10 to 50 cm. 4. A plurality of spun yarns are respectively heated and drawn in a plurality of cylindrical heating devices connected in series, and an upper part of a protective cylinder provided on the upper part of each cylindrical heating device is adjacently protected. The method for producing a polyester fiber according to claim 1, 2 or 3, wherein the upper surface of the cylinder is closely contacted with the upper surface of the cylinder so that a gap is not formed.