JPH1193018A - Production of extrafine polyester yarn - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of producing an extrafine polyester yarn excellent in mechanical characteristics and dyeability, having <=1 denier single yarn fineness. SOLUTION: Dried polyester chips are retained in an atmosphere having -10 to 10 deg.C dew point for >=10 minutes, melted and delivered from a spinneret and taken-off at >=3,000 m/minute speed. Then the taken-off undrawn yarn is not taken-up once and continuously drawn at <=1.2 times draw ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing ultrafine polyester fiber. More specifically, the present invention provides
The present invention relates to a method for extremely stably producing an ultrafine polyester fiber having a single-fiber fineness of 1 denier or less having excellent mechanical properties and dyeing properties.

[0002]

2. Description of the Related Art Cloths made of ultra-fine polyester fibers having a single-fiber fineness of 1 denier or less exhibit an excellent texture and can be brushed to obtain a natural leather-like fabric, and a fine structure is formed. Utilizing this, it is widely used for medical, clothing, household cleaning tools and the like.

[0003] Conventionally, in order to produce such ultrafine fibers,
(1) a method of dissolving and removing the sea component of the sea-island composite fiber, (2)
A method of splitting the spliced conjugate fiber, (3) a method of stretching the spun yarn at a high magnification by flow stretching or the like, and then performing a normal neck stretching, and (4) a method of performing a normal spinning and stretching step. And (5) spinning at a high speed of 3000 m / min or more to directly obtain ultrafine fibers. However, of these methods (1) and (2), a special spinning device is required, and it is necessary to use two or more kinds of polymers, and further, operations such as dissolution and splitting are required. There is a disadvantage that it is very expensive to do so. Further, the methods (3) and (4) have a problem that the number of broken yarns during drawing increases as the single-filament fineness decreases.
On the other hand, according to the high-speed spinning method proposed in Japanese Patent Publication No. 62-11685 and the like, there is an advantage that ultrafine fibers can be obtained relatively easily. However, the ultrafine fibers obtained by such a method have a problem that the Young's modulus is too low.

In order to solve this problem, Japanese Patent Publication No.
Japanese Patent No. 3615 proposes a method in which undrawn yarn obtained by high-speed spinning is continuously drawn without being wound once to obtain ultrafine fibers. However, since the ultrafine fibers obtained by such a method are continuously drawn after high-speed spinning, although the mechanical properties of the obtained ultrafine fibers are improved, there is a problem that the spinnability deteriorates.

Further, in the case of producing ultrafine polyester fibers having a single fiber fineness of 1 denier or less, it is necessary to extremely increase the deformation speed under the spinneret. However, there has been a problem that spinning stability is reduced due to thermal degradation of polyester and generation of foreign matter. This problem of melt viscosity can be solved by lowering the degree of polymerization of polyester, but it is necessary to change the degree of polymerization for each brand, and more than one chip bunker for temporarily storing chips is required, which makes capital investment. However, there is a problem that the cost is greatly increased due to an increase in the size and the time required for chip switching, and the generation of foreign substances in the polyester is not sufficiently suppressed.

[0006] Further, there is a problem that ultrafine fibers appear pale even when dyed under the same conditions. However, if the spinning temperature is lowered to improve this problem, there is also a problem that spinning stability deteriorates.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and makes it possible to extremely stably produce ultrafine polyester fibers having excellent mechanical properties and dyeing properties even if the single-fiber fineness is 1 denier or less. The aim is to provide a method that can be manufactured.

[0008]

According to the study of the present inventors, the above-mentioned problem is solved by "drying polyester chips in air or an inert gas atmosphere having a dew point of -10 to 10 ° C.
After holding for 0 minutes or more, melt and discharge from the spinneret,
Taking up at a speed of 0 m / min or more, and then continuously drawing the undrawn drawn yarn at a magnification of 1.2 times or less without winding it once, wherein the single yarn fineness is 1 denier or less. It can be achieved by the "method for producing ultrafine polyester fiber".

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the production method of the present invention, when a dried polyester chip is melted and melt-discharged from a spinneret, the dried chip is previously defrosted by -10.
It is important that the polyester chips absorb moisture by keeping them in an air or inert gas atmosphere at -10 ° C for 10 minutes or more. By doing so, when the polyester chips are melted and discharged from the spinneret, the hydrolysis of the polyester proceeds and the melt viscosity can be lowered even when the spinning temperature is lowered, and the deformation rate under the spinneret is increased. Even then, it is possible to stably spin.
Further, the generation of foreign matter in the polymer is suppressed, and the mechanical properties of the obtained fiber are improved. Here, when the dew point of the air or inert gas atmosphere is lower than -10 ° C, the amount of humidification into the chip becomes insufficient, and the object of the present invention cannot be achieved, which is not preferable. On the other hand, if it exceeds 10 ° C,
It is not preferable because dew condensation easily occurs in a chip hopper or the like holding the chips, and the amount of humidification in the chips cannot be controlled. Any inert gas may be used as long as it does not react with the polyester.
Argon gas or the like can be used. Further, if the holding time in the atmosphere is less than 10 minutes, the variation in the amount of humidification into the chips increases, so that not only the quality of the obtained ultrafine fibers varies, but also the spinning stability decreases. Not preferred. The upper limit of the holding time is not particularly limited, but if it is too long, the required capacity of the hopper becomes large and the initial equipment investment becomes large.

FIG. 1 shows an example of an apparatus used for humidifying the above-mentioned polyester chips. In the figure, dried polyester chips are first put into an upper hopper 1 and then supplied to a lower hopper 2. The supplied chips are appropriately adjusted by the humidified air supplied from the humidified air inlet pipe 4 for the chip moisture.
It is led to.

The polyester chips humidified as described above are melted and discharged from the spinneret after being melted.
The melting temperature and the spinning temperature are 295 ° C. or less, preferably 28 ° C.
It is desirable to be 5 to 290 ° C. If the temperature exceeds 295 ° C., the thermal degradation of the polyester proceeds, the amount of foreign matter generated in the polymer increases, and it becomes difficult to stably spin ultrafine fibers. In addition, the dyeability of the obtained fiber is also reduced, and the fiber is easily lightened.

Next, it is necessary to apply the oil agent to the melt-discharged yarn after cooling and solidifying, and then to take the yarn at a speed of 3000 m / min or more. If the take-up speed is less than 3000 m / min, the discharge amount per discharge hole required to obtain an ultrafine fiber having a single-fiber fineness of 1 denier or less becomes small. This is not preferred because not only does it occur, but also the yarn is likely to break in the spinning process, and also to the breaking in the subsequent drawing process. Furthermore, when the take-off speed is reduced, the stretching ratio for providing sufficient mechanical properties is increased, so that not only the yarn is easily broken in the stretching process, but also the disorder of the orientation of the amorphous portion is reduced and the dyeing is performed. It is not preferable because the property is lowered.

[0013] The undrawn yarn subsequently taken up is continuously 1.20 times or less, preferably 1.0 times or less, without being wound up once.
It is necessary to stretch at a magnification of 5 to 1.20. If the draw ratio exceeds 1.20, not only yarn breakage is likely to occur, but also the dyeing property is undesirably reduced.

The polyester to be used in the present invention is preferably a polyethylene terephthalate-based polyester whose main repeating unit is composed of ethylene terephthalate units, and its intrinsic viscosity is suitably in the range of 0.5 to 0.8. Any additives may be added to the polyester within a range that does not impair the object of the present invention. For example, when titanium oxide is added as a matting agent, 3.0% by weight or less is added. Can be.

[0015]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. In addition, each evaluation item in an Example was measured according to the following method. <Process condition> 24 spinning machines with 4 spindles were operated for 3 days.
It was expressed as the number of yarn breaks per day. <Spinner foreign matter> After spinning for 3 days, the height of the foreign matter deposited around the spinneret nozzle hole was measured, and the maximum height was shown. <Dyeing Property> Terraseal blue was used as a dye, and dyed under normal pressure at a temperature of 100 ° C., and the dyed state was visually determined.

Example 1, Comparative Examples 1-4 A polyethylene terephthalate chip having an intrinsic viscosity of 0.64 was placed in a chip hopper whose atmosphere was maintained at the dew point shown in Table 1.
Then, the mixture was melted and discharged from a spinneret having a discharge hole having a hole diameter of 0.15 mm and 72 holes at a spinning temperature shown in Table 1. The discharged yarn was cooled and solidified, then applied with an oil agent, taken up at the speed shown in Table 1, stretched without being wound once, and then wound at a speed shown in Table 1 to obtain 32 denier / 72 filaments. An extra fine fiber was obtained.
Table 1 shows the results. The dew point of the atmosphere in the chip hopper was controlled by supplying air having a dew point of 5 ° C. based on the measurement value of a dew point meter installed in the chip hopper.

[0017]

[Table 1]

[0018]

As described above, according to the production method of the present invention, it is possible to increase the deformation speed during spinning even if the spinning temperature is lowered, and to suppress the generation of foreign matter in a spinneret during spinning. Therefore, it is possible to extremely stably produce an ultrafine polyester fiber having excellent mechanical properties and good dyeing properties.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one example of equipment used in the present invention.

[Description of Signs] 1 Upper hopper 2 Lower hopper 3 Screw 4 Humidified air inlet pipe 5 Humidified air outlet pipe

Claims (1)

[Claims] 1. A dried polyester chip is held in an air or inert gas atmosphere having a dew point of -10 to 10 ° C. for 10 minutes or more, and then melted and discharged from a spinneret.
m / min or more, and then draw the undrawn yarn continuously at a magnification of 1.2 times or less without winding once, wherein the single yarn fineness is 1 denier or less. A method for producing ultrafine polyester fibers.