JPH06128811A - Production of polyester fiber - Google Patents

Abstract

PURPOSE:To efficiently obtain polyester fibers by cooling and solidify a polyester delivered through a spinneret and by reheating the resultant yarns under a specified temperature gradient before takeup to enable various kinds of products to be produced without the need for changing spinning speed with higher successful winder switching rate. CONSTITUTION:A polyester is delivered at about 290 deg.C through a spinneret 1, the resultant filament yarns Y are passed through a thermal insulating zone 2 under the spinneret 1 and perpendicularly subjected to air flow by a chimney 3 to cool the yarns Y to room temperature and solidify them followed by introducing the solidified yarns into a heating zone such as a hot tube 4 set up under the spinneret 1. The heating gradient in this zone is set according to the formula, [where, Tc is the atmospheric temperature at the center of the zone ( deg.C); Ti is the atmospheric temperature at the inlet of the zone ( deg.C); To is the atmospheric temperature at the outlet of the zone ( deg.C)] and, under this condition, the yarns are drawn and heat set followed by oiling with a relevant device 5 and then interlacing them with a relevant device 6 and takeup with a pair of goddet rolls 7 and then winding the heatset yarns on a winder 8, thus obtaining objective polyester fibers so as to enable various kinds of products to be produced without the need for changing spinning speed.

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 particularly to a method for producing a polyester fiber satisfying the characteristics that can be put to practical use only in a spinning step, and more specifically, a polyester fiber having a large residual elongation The present invention relates to a manufacturing method.

[0002]

2. Description of the Related Art In recent years, a high-speed spinning method capable of obtaining fibers sufficiently satisfying practical properties without passing through a drawing step by setting a take-up speed to 4000 m / min or more is aimed at improving productivity. It has been developed and put to practical use. This high-speed spinning method includes an ultra-high-speed spinning method in which the yarn melt-discharged from the spinneret is drawn as it is at 5000 m / min or more, and once it is cooled and solidified, it is drawn and heat-treated while being reheated in a heating atmosphere such as a hot tube. 40 m / min or more by a hot tube stretch-spinning method in which a first take-up roll is used to draw and then a second take-up roll is used to draw 40
There is a direct spinning and drawing method in which the fiber is drawn at a rate of 00 m / min or more.

Of these, the yarns obtained by the ultra-high speed spinning method have good dyeability and are soft because they have a small Young's modulus, but since their physical properties and fiber structure are essentially different from those of conventional drawn yarns, Cannot be used as a substitute for the drawn yarn of On the other hand, the yarn obtained by the hot tube draw-spinning method has physical properties close to those of a so-called drawn yarn, which is a yarn produced by a conventional two-step spinning / drawing method. .

However, in the hot tube draw spinning method,
The heating zone cannot be moved along the spinning line except that its position can be finely adjusted for the purpose of adjusting the yarn path, and is substantially fixed. Therefore, for example, it is attempted to manufacture ultrafine fibers having a single yarn fineness of 1.5 denier or less without changing the position of the heating area in an apparatus for producing a normal type having a single yarn fineness of 1.5 to 3 denier. Then, only a yarn having a low elongation, which is a practical problem, can be obtained. In the manufacturing process, low elongation yarn has a low switching success rate when wound by an automatic switching winder with high productivity, and there is a problem that the package cannot be taken out from the winder due to winding tightness. At times, there were problems such as increased fluff and yarn breakage in the weaving process. To solve this problem, Japanese Patent Laid-Open No. 62-1620
Japanese Patent Publication No. 15 proposes to control the yarn tension in the heating region by adjusting the position of the heating region and the spinning take-up speed for each product type to make the obtained yarn practicable.

However, since the position of the heating region is substantially fixed in the usual yarn manufacturing apparatus, a new device for changing the position is required to change the position of the heating region. In addition, it is necessary to frequently move the heating zone to cope with the diversification of fiber types, and the production efficiency decreases due to the work of changing the position and the work of adjusting the yarn path after the position change. There was a problem. Furthermore, even if the position of the heating zone is changed, the types of products that can be produced at the changed position are limited, and in order to produce other types, it is necessary to change the position of the heating zone. It was On the other hand, if the position of the heating area is fixed, the take-up speed has to be reduced for finer denier in order to prevent lower elongation, leading to a reduction in productivity.

[0006]

DISCLOSURE OF THE INVENTION The object of the present invention is to enable the production of a large number of varieties, including ultrafine varieties with a single yarn denier of 1.5 denier or less, without reducing the spinning speed in the hot tube drawing and spinning method. To do so.

[0007]

Means for Solving the Problems The above-mentioned object of the present invention is to perform melt spinning in which a polyester is discharged from a spinneret, cooled and solidified, and then reheated in a heating zone up to a take-up device. It can be achieved by a method for producing a polyester fiber, characterized in that the gradient is represented by the following formula (1). Tc-Ti ≧ 3.0 (To-Tc) (1) (where Tc is the ambient temperature (° C.) in the center of the heating zone, Ti
Is the ambient temperature at the inlet of the heating zone (° C), To is the ambient temperature at the outlet of the heating zone (° C))

The present invention will be described in detail below. First, the method for producing a polyester fiber of the present invention will be specifically described with reference to FIG. The polyester is discharged from the base 1 at about 290 ° C. After passing the discharged yarn Y through the heat-retaining zone 2 under the spinneret 1, the chimney 3 blows air perpendicularly to the yarn to cool it once to room temperature, and then the hot tube 4 installed under the spinneret 1 After being introduced into the inside, drawn and heat-treated, oil is supplied by the oil supply device 5, subsequently entangled by the entanglement device 6, taken up by the pair of gody rolls 7, and wound by the winder 8 to obtain the polyethylene fiber of the present invention. With the polyester in the present invention, it is preferable that the main dicarboxylic acid component constituting the polyester is a terephthalic acid component, but other dicarboxylic acid components may be used or used in combination without departing from the object of the present invention. The main diol component constituting the polyester of the present invention is preferably ethylene glycol, but other components such as 1,4-butanediol, 1,6-hexanediol, polyethylene glycol, polytetramethylene glycol, 1,4- A diol component such as cyclohexanedimethanol may be used or used in combination without departing from the object of the present invention. Further, various additives such as a matting agent, a flame retardant, an antioxidant, an ultraviolet absorber, an infrared absorber, a crystal nucleating agent, and a brightening agent may be added to the polyester of the present invention as required. It may be copolymerized or mixed.

In melt spinning, the polyester melted and discharged from the spinneret is once cooled by cooling air. The cooling is performed until the temperature at which the polyester yarn solidifies, that is, the glass transition temperature or less, so that the subsequent drawing heat treatment can be stably performed. If the yarn is introduced into the heating zone before sufficient cooling takes place, the drawing becomes unstable and the homogeneity of the obtained yarn is impaired.

The distance from the spinneret surface to the inlet of the heating zone is, in the case of a normal single yarn denier of 1.5 to 3.0 denier, due to sufficient yarn cooling below the spinneret surface, workability, and air resistance. Considering the tension generated, 1.0 to 2.5 m is preferable, and 1.5 to 2.0 m is more preferable. In the present invention, the once cooled yarn is introduced into a heating zone having a temperature gradient defined by the following formula (1), and reheated and subjected to a stretching heat treatment. Tc-Ti ≧ 3.0 (To-Tc) ... (1) (where Tc is the atmospheric temperature (° C.) in the center of the heating zone, Ti
Is the ambient temperature at the inlet of the heating zone (° C), To is the ambient temperature at the outlet of the heating zone (° C))

Ti or To is the atmospheric temperature at the center of the yarn at the inlet or outlet of the heating zone, and Tc is the atmospheric temperature measured at a position about 3 mm away from the inner wall of the central portion of the heating zone by inserting a thermocouple inside the heating zone. Is.

Here, the heating zone inlet means the point where the yarn enters the heating device and begins to be heated, as indicated by A in FIG. The heating zone outlet is the point B at which the yarn comes out of the heating device.
Say. The temperature gradient of the heating zone defined by the formula (1) of the present invention is a method of providing an associated airflow separating device at the inlet or the outlet of the heating zone. As shown in FIG. It is achieved by providing a multi-stage hot tube consisting of ′ and controlling the upper part of the heating zone to a high temperature and the lower part to a low temperature. Although the method for achieving the same is not limited in any way, it is preferable to provide an associated airflow separation device in view of facility simplicity and operation cost.

When the temperature gradient in the heating zone is out of the range of the formula (1), when producing fibers having a single yarn of 1.5 denier or less,
Since the residual elongation of the obtained fiber is reduced, it is necessary to reduce the spinning speed, the productivity in the manufacturing process is reduced, and the process passability in high-order processing is also poor. The atmosphere temperature Tc of the central portion of the heating region is preferably within the range of the formula (1), and is a temperature at which the fiber retains practical strength and does not cause treatment unevenness, which is the glass transition temperature of the polyester. 80
C. or higher, and for sufficient heat treatment, 110.degree. C. or higher is preferable, and 130.degree. C. or higher is more preferable. Also, Tc is
In order to obtain homogeneity between the single yarns in the longitudinal direction of the fiber and a uniform yarn, the melting point or lower is preferable, and 200 ° C. or lower is more preferable from the viewpoint of energy cost.

FIG. 3 shows the temperature distribution in the heating area. No. 3 in FIG. 1 is the temperature distribution of the present invention,
Formula (1) is satisfied. No. 2 is the temperature distribution outside the present invention. No. When the temperature distribution defined by the formula (1) is used as in 1, the ultrafine product with a single yarn of 1.5 denier or less can be wound with high elongation without lowering the spinning speed, which is the object of the present invention. . Although the reason for this is not clear, No. 1 in FIG. Two
When the temperature of the latter half is high as described above, it is presumed that the yarn is exposed to high stress due to air resistance and a high temperature atmosphere to cause excessive stretching, resulting in low elongation.
No. 1 of the present invention. In the temperature distribution of No. 1, since the temperature of the latter half is moderately low, it is considered that such excessive stretching does not occur and the elongation reduction can be suppressed.

All the curves in FIG. 1 show the same heat setting property, that is, the temperature gradient required for the same boiling water shrinkage when the spinning method of the present invention is applied under the condition of 5000 m / min. Shows. Although it is not clear why the elongation of the ultrafine yarn having a single yarn of 1.5 denier or less increases due to the temperature gradient in the heating region shown in the formula (1) of the present invention, the effect of the formula (1) becomes more remarkable. It is more preferable that the heating zone has a temperature gradient defined by the following formula (2) in order to develop the phenomenon. Tic-Ti ≧ 1.25 (Tc-Tic) ... (2) (where Tic is the ambient temperature at the midpoint between the heating zone inlet and the center (° C), Ti is the ambient temperature at the heating zone inlet (° C)) , Tc
Is the ambient temperature (° C.) in the center of the heating area. ) Here, the method of measuring the atmospheric temperature Tic at the midpoint between the inlet of the heating zone and the center is in accordance with that of Tc.

The reason why the elongation can be increased by satisfying the expression (2) is that the drawing position can be brought closer to the spinneret by rapidly raising the temperature of the yarn, and the tension applied to the yarn at the drawing position can be reduced. Therefore, it is considered that the effect of increasing the draw ratio, that is, increasing the elongation of the drawn yarn is exhibited. When using the associated airflow separating device to achieve the temperature gradient specified in the present invention, in order to allow the yarn to freely stretch in the heating zone, anything other than the inlet or outlet associated airflow separating device is applied to the yarn. It is preferable not to contact.

The associated airflow separating device is a device having a function of positively separating the associated airflow of the yarn from the yarn by bringing the yarn into proximity with or in contact with the running yarn.

The associated airflow separating device may be provided at either the inlet or the outlet of the heating zone, or may be provided at only one of the heating region. However, since the undrawn yarn is easily scratched by rubbing with the separating device, yarn breakage occurs. In order to prevent the occurrence of fluff in the drawn yarn and the reduction in strength, it is preferable to provide the entrained airflow separating device at the outlet portion which comes into contact with the drawn yarn. The cross-sectional shape of the yarn running portion of the associated airflow separating device can be any shape, and specifically, the following associated airflow separating device can be used.
In the present invention, when the yarns are bundled by the associated airflow separating device, the heat exchange at the central portion of the yarns is reduced, and uneven drawing occurs or heat setting property becomes insufficient, resulting in a difference in physical properties between single yarns. In order to perform sufficient heat treatment while effectively separating the accompanying airflow, it is preferable that the cross-sectional shape be a slit shape as shown in Fig. 4 so that the heat treatment can be performed by aligning the yarns, and the slit width D is 2 mm. The following is more preferable, 1 mm
The following is more preferable. Further, when the cross-sectional shape is slit-like, it is preferable to run the yarns so that the yarns are not unevenly distributed at one end of the slits in order to prevent a difference in physical properties between the single yarns. For that purpose, for example, a method is adopted in which the direction of the slit is set such that the yarn collecting guide below the slit and the direction thereof are twisted. Further, when the yarn passes through the associated airflow separation device, it is preferable that the yarn comes into contact with the separation device because the flow rate of the associated air flowing out from the heating area decreases, but other methods such as blowing air to the traveling yarn are adopted. If so, the yarn and the separating device may not be in contact with each other.

As the heating area, a tube or a tube having a rectangular cross section can be used, but any shape can be used as long as it can heat the space in which the yarn runs. As a heating method of the heating area, there is a method of heating with a heating medium or a heating wire from the surroundings, dry heated air introduced by heating, a method of filling saturated steam or heating steam, but in order to uniformly heat the heating area, A heating medium heating method, a method of introducing a heating medium into the heating zone, and a method of combining these are preferable. The length of the heating region is preferably 0.5 to 3.0 m from the viewpoint of stable stretching heat treatment and energy saving,
1.0 to 2.0 m is more preferable. The take-up speed is determined in consideration of the fineness of the obtained fiber, mechanical properties, spun yarn breakage, productivity improvement and the like. In order to obtain a conventional drawn yarn only by the spinning process, it is preferably 4000 m / min or more and 4500
It is more preferably m / min or more.

[0020]

EXAMPLES Each characteristic value in the examples was determined according to the following method. (A) Atmosphere temperature measurement Using a CA thermocouple, measurement was performed during spinning. (B) Strength and Elongation of Fiber It was determined from a load extension curve using a Tensilon tensile tester manufactured by Orientec. (C) Dyeing unevenness After the obtained yarn was formed into a tubular knit, it was dyed and visually checked for the presence of dyeing unevenness. (D) Spinnability Evaluation was made by the number of yarn breakages when spinning 1000 kg. A: Number of thread breaks 0 or 1 B: Number of thread breaks 2 to 5 C: Number of thread breaks 6 or more

Examples 1 to 3 and Comparative Example 1 Polyester having an intrinsic viscosity [η] = 0.64 was melted at 290 ° C., and the spinning device shown in FIG. . After passing the discharged yarn through the heat-retaining zone (about 20 cm) under the spinneret, blow air at 25 m / min, about 25 ° C, perpendicularly to the yarn for 1 m to cool the yarn once to room temperature. The yarn was introduced into a hot tube with a length of 1.5 m and an inner diameter of 30 mmφ installed 2 m below the spinneret, and after drawing heat treatment, lubrication and entanglement were applied to 5000 m /
A polyester fiber of 50 denier / 48 filaments was obtained by taking up with a pair of goddy rolls and winding with a winder.

Table 1 shows the inlet shape, outlet shape, ambient temperature, and temperature of the associated airflow separator attached to the hot tube inlet.
The yarn characteristics and the spinnability of the obtained fiber were shown. As is clear from this table, when the expressions (1) and (2) are satisfied, a yarn having a residual elongation that is practically sufficient can be obtained. Here, the practically sufficient residual elongation is 30% or more, and more preferably 33% or more.

[0023]

[Table 1] Examples 4 to 5 and Comparative Example 2 The thickness of the yarn taken up is 50 denier / 72 filaments,
The same method as in Example 1 was carried out except that the die was changed to 50 denier / 24 filament. Table 2 shows the conditions of the hot tube and various properties of the obtained fiber. When the single yarn fineness is 1 denier or less, a yarn having a practically sufficient residual elongation can be obtained if the formulas (1) and (2) are satisfied. Further, even when the method of the present invention is adopted when the single yarn fineness is larger than 1 denier, the residual elongation does not change significantly, and the yarn having the conventional yarn quality can be produced.

[0024]

[Table 2]

[0025]

The following effects can be obtained by adopting the method of the present invention. (1) By improving the type compatibility at the heating zone position, various types of different types can be manufactured without changing the spinning speed. (2) Since a yarn having a practically sufficient residual elongation can be obtained, the success rate of switching when using the automatic switching winder can be significantly improved.

[Brief description of drawings]

FIG. 1 is a schematic view of a method for producing a polyester fiber of the present invention.

FIG. 2 is a schematic view of a hot tube for suitably making the heating zone of the present invention.

FIG. 3 shows a temperature gradient (NO. 1) in the heating zone of the present invention and a temperature gradient (NO. 2) of the present invention.

FIG. 4 is a schematic view of an associated airflow separation device that is preferably used in the method for producing a polyester fiber of the present invention.

[Explanation of symbols] 1 mouthpiece 2 heat insulation zone 3 chimney 4 hot tube 5 oil supply device 6 confounding device 7 Gody roll 8 winder 9 9'heater 10 heat insulator

Claims (2)

[Claims] 1. In melt spinning in which polyester is discharged from a spinneret, cooled and solidified, and then reheated in a heating zone up to a take-up device, the temperature gradient in the heating zone is expressed by the following formula (1).
And a method for producing a polyester fiber. Tc-Ti ≥ 3.0 (To-Tc) (1) (where Tc is the atmospheric temperature (° C) in the center of the heating zone, Ti
Is the ambient temperature at the inlet of the heating zone (° C), To is the ambient temperature at the outlet of the heating zone (° C)) 2. The method for producing a polyester fiber according to claim 1, wherein the temperature gradient in the heating zone is represented by the following formula (2). Tic-Ti ≧ 1.25 (Tc-Tic) (2) (where Tc is the atmospheric temperature (° C.) in the center of the heating zone, Ti
Is the ambient temperature at the inlet of the heating zone (° C), Tic is the ambient temperature at the midpoint between the inlet of the heating zone and the center (° C))