JPH06294008A - Production of polyester fiber - Google Patents

Abstract

PURPOSE:To enable the production of a number of various kinds of polyester fibers without changing the spinning speed by properly adjusting the position of a heating cylinder corresponding to the kind of the fiber to be produced. CONSTITUTION:In the melt-spinning of a polyester comprising the reheating of a cooled and solidified polyester, a heating cylinder composed of an outer cylinder 10 and an inner cylinder 11 is used and a yarn Y is introduced into the inner cylinder 11 to induce a circulation flow in the heating cylinder and attain a temperature gradient in the heating cylinder satisfying the formula Tc-Ti>=3.0(To-Tc), wherein Tc ( deg.C) is atmospheric temperature in the inner cylinder at the center of the heating cylinder; Ti ( deg.C) is atmospheric temperature at the inlet port of the heating cylinder; T0 ( deg.C) is the atmospheric temperature at the outlet port of the heating cylinder. Since a yarn having practically sufficient residual elongation is producible by this process, the exchange success ratio of an automatic exchanging winder is remarkably improved.

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 has been developed for the purpose of improving productivity, in which a fiber capable of sufficiently satisfying practical characteristics can be obtained without a drawing process by setting a take-up speed to 4000 m / min or more. It has been 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, once cooled and solidified, and then drawn and heat-treated while being reheated in a heating tube such as a hot tube. 4000 m / minute by drawing with a first take-up roll and then drawing with a second take-up roll.
There is a direct spinning drawing method in which the film is drawn at a speed of at least 1 minute.

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, There are limited uses that can be used as a substitute for so-called drawn yarns produced by the two-step spinning and drawing process. On the other hand, the yarn obtained by the hot tube draw-spinning method has physical properties similar to those of conventional drawn yarns, and thus can be applied to a wide range of applications. Further, the process is simpler than that of the direct spinning and drawing method, and the cost merit is large.

Conventionally, in the hot tube draw-spinning method, the heating cylinder is not movable along the spinning line except for finely adjusting its position for the purpose of adjusting the yarn path, and is substantially fixed. ing. Therefore, for example, when an ultrafine fiber having a single yarn fineness of 1.5 denier or less is produced as it is without changing the heating cylinder position in an apparatus for producing a normal type having a single yarn fineness of 1.5 to 3 denier, Only threads with low elongation are practically available. The low elongation yarn has a poor switching success rate when wound by an automatic switching winder having high productivity in the yarn manufacturing process, and causes problems such as the package cannot be taken out from the winder due to winding tightness. Further, when it is made into a product, there is a problem that fluff and yarn breakage increase in the weaving process. To solve this problem, JP-A-62-1
According to Japanese Patent No. 62015, by adjusting the position of the heating cylinder and the spinning take-up speed for each type, the yarn tension in the heating cylinder is controlled, and the mechanical properties of the obtained yarn are made practical.

However, since the position of the heating cylinder is substantially fixed in the ordinary yarn making apparatus, a new device for changing the position is required to change the position of the heating cylinder. In addition, it is necessary to move the heating cylinder frequently in order to cope with the diversification of fiber types, and the production efficiency decreases because of the work of changing the position and the work of adjusting the yarn path after the position change. There was a problem. On the other hand, if the position of the heating cylinder is fixed, the take-up speed is inevitably decreased as much as the production of fine denier is attempted in order to prevent the reduction of elongation, and the productivity is reduced.

As a technique similar to the present invention, there is Japanese Patent Laid-Open No. 54-138613 in which an inner cylinder is provided in a heating cylinder. The publication uses an entrained airflow separator and radiant heat from a heating element in order to perform sufficient heat treatment in a heating cylinder, but the inner cylinder of the publication does not generate a vortex that occurs on the downstream side of the entrained airflow separator. It is attached for the purpose of suppressing and preventing the occurrence of stretch unevenness of the yarn due to vortex flow.

Further, in this publication, the associated airflow separating device is installed above the heating cylinder, but when a fine denier yarn is passed through, it is rubbed at the inlet part of the associated airflow separating device, and fluff and slack are generated. It becomes a problem when you do. Further, not only fine denier yarns but also yarns before heat treatment are bundled, and sufficient heat exchange cannot be performed inside the heating cylinder, which causes unevenness of heat treatment.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to include an ultrafine product having a single yarn fineness of 1.5 denier or less in a hot tube drawing and spinning method without lowering the spinning speed which was a drawback of the prior art. , To efficiently manufacture a wide variety of products.

[0009]

The above-mentioned object of the present invention is to perform melt spinning in which polyester is discharged from a spinneret, cooled and solidified, and then reheated by a heating cylinder until a take-up device. It is composed of a cylinder and an inner cylinder, and a yarn is introduced into the inner cylinder to form a circulation flow inside the heating cylinder, whereby the temperature gradient in the heating cylinder is calculated by the following equation (1).
It can be achieved by a method for producing a polyester fiber characterized by Tc-Ti ≧ 3.0 (To-Tc) (1) (where Tc is the atmospheric temperature (° C.) inside the inner cylinder at the center of the heating cylinder, Ti is the atmospheric temperature (° C.) at the inlet of the heating cylinder, To Is the ambient temperature (° C) of the heating cylinder outlet)

The present invention will be described in detail below. First, an example of 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 below the spinneret, air is blown by the chimney 3 perpendicularly to the running direction of the yarn to once cool it to near room temperature, and then heat it installed below the spinneret. Introduced in cylinder 4,
After the drawing heat treatment, oil is fed and entangled by the oil supply device 5 and the entanglement imparting device 6, and is taken up by a pair of Gody rolls 7 and wound on a winder 8.

The main dicarboxylic acid component constituting the polyester in the present invention is preferably 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 is preferably ethylene glycol, but other components such as 1,4-butanediol and 1,6-
Hexanediol, polyethylene glycol, polytetramethylene glycol, 1,4-cyclohexanedimethanol and other diol components may be used or used in combination without departing from the object of the present invention.

Various additives such as a matting agent, a flame retardant, an antioxidant, an ultraviolet absorber, an infrared absorber, a crystal nucleating agent and a fluorescent brightening agent are copolymerized or mixed as required. May be.

In the present invention, the polyester melted and discharged from the spinneret is once cooled by cooling air or the like. It is preferable to cool the polyester yarn to a temperature at which it solidifies, that is, a glass transition temperature or lower so that the subsequent stretching heat treatment can be stably performed. If the yarn is guided to the heating cylinder before sufficient cooling is performed, the drawing becomes unstable,
The homogeneity of the obtained yarn will deteriorate.

The distance from the die surface to the inlet of the heating cylinder is preferably 1.0 to 2.5 m in consideration of sufficient yarn cooling under the die surface, workability, and tension generated by air resistance. It is more preferably 0.5 to 2.0 m.

In the present invention, the once cooled yarn is introduced into a heating cylinder having a temperature gradient defined by the following equation (1), reheated and subjected to a stretching heat treatment. Tc-Ti ≧ 3.0 (To-Tc) (1) (where Tc is the atmospheric temperature (° C.) inside the inner cylinder at the center of the heating cylinder, Ti is the atmospheric temperature (° C.) at the inlet of the heating cylinder, To Is the atmospheric temperature (° C) at the outlet of the heating cylinder) Ti (° C) or To (° C) is measured by inserting a thermocouple into the center of the yarn at the inlet or outlet of the heating cylinder. Also, T
c (° C): Insert the thermocouple inside the inner cylinder, and remove about 3 from the inner cylinder wall.
Measure at a position separated by mm. Here, the heating cylinder inlet refers to a point where the yarn enters the heating cylinder and begins to be heated, as shown by A in FIG. The heating cylinder outlet means a point B at which the yarn comes out of the heating cylinder.

When the temperature gradient of the heating cylinder is out of the range of the formula (1), when a fiber having a denier of 1.5 denier or less is produced,
The residual elongation of the obtained fiber decreases, the switching success rate decreases, and high-order passability becomes poor. In order to prevent this, it is necessary to reduce the spinning speed, which lowers the productivity in the manufacturing process.

FIG. 3 shows the temperature distribution in the heating cylinder. No. 1, No. 5000m / for both 2
It shows a temperature distribution where the boiling water shrinkage is the same under the condition of minutes. 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 is defined by the formula (1) as in 1, the ultrafine product having 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 in 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, the temperature of the latter half is moderately low, and therefore it is considered that such excessive stretching does not occur and the elongation reduction can be suppressed.

With respect to the temperature gradient in the heating cylinder defined by the formula (1) of the present invention, the inner cylinder is inserted into the heating cylinder, and the yarn is introduced into the inner cylinder to circulate inside the heating cylinder. This can be achieved by forming a stream. Circulating flow passages are provided in the upper and lower portions of the heating cylinder so that a circulating flow can be formed inside the heating cylinder. Then, in the heating cylinder, an airflow is generated in the yarn direction along with the yarn traveling inside the inner cylinder, and in the upper part of the inner cylinder, the airflow is sucked into the airflow so that the yarn is interposed between the outer cylinder and the inner cylinder. The airflow flowing in the direction opposite to the running direction flows into the inner cylinder, and conversely, in the lower part of the inner cylinder, a part of the airflow accompanying the yarn flows into the space between the outer cylinder and the inner cylinder to circulate. Is formed.

In order to form the circulation flow, for example, as shown in FIG. 2, the inner cylinder is shorter than the outer cylinder, and there are portions not having a double pipe structure above and below the inner cylinder. Such a structure, or a structure in which through holes are provided at the upper and lower ends of the inner cylinder for the inflow and outflow of the airflow, respectively.
FIG. 2 shows an example of a heating cylinder that can be preferably used in the present invention. However, if the temperature gradient in the heating cylinder defined by the formula (1) of the present invention can be achieved by installing the inner cylinder, The method is not particularly limited to this example. Inner cylinder 11
Are installed substantially concentrically inside the outer cylinder 12, and the inner cylinder is supported by a support plate 13 mounted between the inner wall surface of the outer cylinder or by a support rod extending from the heating cylinder inlet / outlet. The length of the inner cylinder, excluding the space where airflow can flow in and out, is preferably at least ½ or more of the length of the outer cylinder, and more preferably ⅔ or more. The ratio of the diameter of the inner cylinder to the outer cylinder and the lengths of the through-holes above and below the inner cylinder are determined in consideration of other spinning conditions. From the viewpoint of operability, it is preferable that the inner diameter of the inner cylinder is larger than the yarn width of the outer cylinder inlet.

By installing the inner cylinder, a circulating flow is formed and the temperature gradient defined by the equation (1) of the present invention is achieved, but in addition, the air flow in the heating cylinder is rectified and the ascending air current is increased. Is prevented from directly hitting the yarn, and uneven stretch due to turbulence of airflow is prevented.

In order to bring out the effect of the formula (1) more significantly, it is preferable that the heating cylinder has a temperature gradient defined by the following formula (2). Tic-Ti ≧ 1.5 (Tc-Tic) (2) (where Tic is the atmospheric temperature (° C) inside the inner cylinder at the midpoint between the heating cylinder inlet and the center) Here, the method for measuring Tic is According to that of Tc.

The temperature gradient defined by the equation (2) is, for example,
This is achieved by a method of installing a guide having a diameter or slit width of 5 mm or less at the heating cylinder outlet. in this case,
More preferably, a slit guide having a slit width of 3 mm or less, more preferably 1 mm or less can be used to form a sufficient circulation flow, and the heated circulation flow can be generated by passing between the outer cylinder and the inner cylinder. It can be introduced inside the inner cylinder where the yarn runs, and the temperature in the first half of the heating cylinder can be rapidly raised. The elongation is increased by satisfying the expression (2). By rapidly raising the temperature of the yarn in the first half of the heating cylinder, the drawing position can be brought closer to the spinneret, and the tension applied to the yarn at the drawing position can be reduced.Therefore, the draw ratio is low, that is, the elongation of the drawn yarn is high. It is considered that the effect that can be achieved is exhibited.

When the outlet of the heating cylinder has a slit shape, in order to prevent a difference in physical properties between single yarns,
It is preferable to run the yarn so that the yarns are not unevenly distributed at the ends of the slits.

The heating cylinder may be cylindrical or rectangular in cross section, but may have any shape as long as it can heat the space in which the yarn runs. As a heating method of the heating cylinder, a method of heating with a heating medium or a heating wire from the surroundings, a method of filling dry hot air introduced by heating, saturated steam or heating steam is adopted, but in order to uniformly heat the heating cylinder. Is preferably a heating medium heating method, a method of introducing a heating medium into the heating cylinder, or a method of combining these. The length of the heating cylinder 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 atmosphere temperature Tc of the central portion of the heating cylinder is preferably within the range of the formula (1), and is a temperature at which the fiber has practical strength and does not cause treatment unevenness, and the glass transition temperature of the polyester. Above, 110 ° C. or higher is preferable for sufficient heat treatment, and 130 ° C. or higher is more preferable. Further, Tc is preferably not higher than the melting point, and more preferably not higher than 200 ° C. from the viewpoint of energy cost, in order to obtain uniformity between the single yarns in the longitudinal direction of the fiber and a uniform yarn.

The area of the inlet of the heating cylinder is preferably 10 mm ² or more, more preferably 20 mm ² or more so that the filaments are not bundled and heat treatment unevenness does not occur inside the heating cylinder. 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 step, it is preferably 4000 m / min or more, more preferably 4500 m / min or more.

[0027]

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 after the temperature became stable in the yarn running state. (B) Fiber Strength and Elongation It was determined from a load extension curve using a Tensilon tensile tester manufactured by Orientec. (C) Spinnability It was evaluated by the number of yarn breakages when spinning 1000 kg. ◎: When the number of thread breaks is 0 or 1 ○: When the number of thread breaks is 2 to 5 ×: When the number of thread breaks is 6 or more

Examples 1 to 3 Polyester having an intrinsic viscosity [η] = 0.64 was melted at 290 ° C., and the spinning device shown in FIG. Keep the discharge thread under the heat insulation zone (2
(0 cm), then the air was blown at a temperature of 25 m / min at 25 ° C perpendicularly to the running direction of the yarn for 1 m to cool the yarn once to room temperature, and the length was set 2 m below the spinneret. By introducing the yarn into a heating cylinder with a length of 1.5 m, drawing and heat treating, feeding and entanglement, taking it up with a pair of gody rolls at 5300 m / min, and winding it with a winder,
A 0 denier / 48 filament polyester fiber was obtained. At this time, a guide having an inner diameter of 10 mm was installed at the inlet of the heating cylinder, the inner diameter of the outer cylinder was 36 mm, the length of the inner cylinder used was 1.0 m, the outer diameter was 30 mm, and the inner diameter of the inner cylinder was 25 mm. The distance from the outer cylinder inlet to the inner cylinder inlet is 0.3.
m.

Table 1 shows the heating cylinder conditions and the yarn characteristics of the obtained yarn. Here, the practically sufficient residual elongation is 30% or more, and more preferably 33% or more.

[0030]

[Table 1] Comparative Examples 1 and 2 Polyester fibers were obtained in the same manner as in Example 1 except that the inner cylinder was not used as the heating cylinder and the atmosphere temperature was changed as shown in Table 1. In both Comparative Examples 1 and 2, the residual elongation is 30% or less, which is not practically applicable.

[0031]

EFFECTS OF THE INVENTION By improving the type compatibility at the heating cylinder position, a large number of different types can be manufactured without changing the take-up speed. Further, since a yarn having a sufficient residual elongation for practical use can be obtained, the success rate of switching when the automatic switching winder is used can be significantly improved.

[Brief description of drawings]

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

FIG. 2 is a specific example of the heating cylinder of the present invention.

FIG. 3 shows a temperature gradient (No. 1) of the heating cylinder of the present invention and a temperature gradient (No. 2) of the present invention.

[Explanation of symbols]

 1 Clasp 2 Insulation Zone 3 Chimney 4 Heating Cylinder 5 Lubrication Device 6 Entanglement Device 7 Gody Roll 8 Winder 9 Heating Body 10 Insulation Body 11 Inner Cylinder 12 Outer Cylinder 13 Indicator Plate

Claims (2)

[Claims] 1. In melt spinning in which polyester is discharged from a spinneret, cooled and solidified, and then reheated by a heating cylinder up to a take-up device, the heating cylinder is composed of an outer cylinder and an inner cylinder. A method for producing a polyester fiber, characterized in that a yarn is introduced into the inside of the heating cylinder to form a circulating flow inside the heating cylinder, whereby the temperature gradient in the heating cylinder is represented by the following formula (1). Tc-Ti ≧ 3.0 (To-Tc) (1) (where Tc is the atmospheric temperature (° C.) inside the inner cylinder at the center of the heating cylinder, Ti is the atmospheric temperature (° C.) at the inlet of the heating cylinder, To Is the ambient temperature (° C) of the heating cylinder outlet) 2. The method for producing a polyester fiber according to claim 1, wherein the temperature gradient in the heating cylinder is represented by the following formula (2). Tic-Ti ≧ 1.5 (Tc-Tic) (2) (where Tic is the atmospheric temperature (° C) inside the inner cylinder at the midpoint between the heating cylinder inlet and the center)