JPH1161567A - Melt spinning of powder-ontaining polyester yarn - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for melt spinning capable of providing a polyester yarn excellent in physical properties without causing discoloration and reduction in physical properties such as strength, elongation, etc., even by mixing powder having a high water content with a fiber-forming polyester in a molten state and spinning the mixture. SOLUTION: In this method for obtaining a polyester yarn containing <=5.0 wt.% based on the total of the yarn of powder by melt spinning by using a twin screw extruder comprising a polymer feed zone 3, a decompressing and kneading zone 4 and an extrusion zone 5 from the upper stream side in a cylinder and equipped with a discharging mechanism for discharging water from the cylinder of the decompressing and kneading zone 4, powder having >=500 ppm water content is supplied to the polymer feed zone 3, the molten polymer is kneaded by a screw in the cylinder of the decompressing and kneading zone 4, water in the powder is separated, the degree of reduction in pressure in the cylinder is adjusted to <=4,000 pa and the spinning is carried out while discharging water from the discharging mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for melt-spinning a polyester fiber containing a powder by melt-mixing a powder capable of imparting various functions to the fiber and a fiber-forming polymer. is there.

[0002]

2. Description of the Related Art Polyesters represented by polyethylene terephthalate have excellent mechanical and chemical properties and are used in a wide range of fields. In recent years, with the diversification of consumer values and increasing awareness of hygiene, the demand for polyester fibers having various functions has been increasing. For example, various kinds of fibers such as antibacterial, deodorant, anti-mite, far-infrared radiation fibers, etc. Functional fibers have been put to practical use.

In order to impart these functions to synthetic fibers such as polyester fibers, there is a method of incorporating powders having these functions. One of the methods is to melt these powders in a fiber-forming polymer. A method of mixing and spinning has been proposed. For example, JP-A-59-133235,
JP-B-63-54103 and JP-A-63-175117 disclose a method in which zeolite particles having antibacterial properties as a powder are melt-mixed with polyester and spun.

[0004] As a method for producing a fiber containing such a powder, a master chip to which a powder is added at a high concentration is prepared in advance, and a fiber-forming polymer is added during spinning to adjust to a desired concentration. And a method of melt-spinning (master chip method) is generally used. On the other hand, synthetic fibers containing zeolite particles having antibacterial properties have good antibacterial and deodorant performance and excellent durability, but such zeolites retain crystal water in a crystal lattice and have a crystal structure. Is characterized by being easy to absorb moisture because it is porous.

[0005] Therefore, when the above-mentioned master chip method is used to obtain a synthetic fiber containing an antibacterial zeolite, the zeolite easily absorbs water, so that water is released at the time of production of the master chip, and the master chip has an extremely small size. There is a problem that not only the viscosity is reduced but also coloring is caused. When melt spinning is performed using such a master chip, hydrolysis of polyester occurs during spinning due to the influence of water generated during the production of the master chip and water of crystallization in the zeolite, and the viscosity of the polymer decreases. There was a problem that fibers having sufficient strength could not be obtained, resulting in colored fibers.

Further, magnesium sulfate added to the fiber-forming polymer as a hygroscopic agent in order to impart hygroscopicity to the fiber is 6 or 7 per mole of magnesium sulfate.
It has moles of water of crystallization, and even if it is dried under reduced pressure at a temperature of 100-200 ° C, more than 1 mole of water of crystallization remains, so using the master chip method, as with antibacterial zeolites, In addition, there has been a problem that the viscosity of the polymer decreases during the production or melt spinning of the master chips, resulting in fibers having poor physical properties such as high elongation, and the produced master chips and fibers are colored.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and, when melt-mixing a powder containing a large amount of water with a fiber-forming polymer and spinning the fiber-forming polymer, spins, coloration, elongation, etc. It is a technical object of the present invention to provide a melt spinning method for polyester, which can obtain polyester fibers having excellent physical properties without lowering the physical properties of the polyester.

[0008]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, mixed and melted powder using a twin-screw extruder equipped with a dewatering mechanism. If melt spinning while discharging water by reducing the pressure in the cylinder, it was found that even if a powder containing a large amount of water was contained, it was possible to produce a polyester fiber without coloration or deterioration in physical properties, The present invention has been reached.

That is, the present invention provides a twin-screw extruder comprising a polymer supply zone, a vacuum kneading zone, and an extrusion zone in the cylinder from the upstream side, and having a discharge mechanism for discharging water from the cylinder in the vacuum kneading zone to the outside of the system. When melt-spinning a polyester fiber containing 5.0% by weight or less of powder based on the fiber weight, the water content is 500 p.
pm or more is supplied to the polymer supply zone, and kneaded with the molten polymer by the screw in the cylinder in the vacuum kneading zone to separate the water in the powder, and the degree of vacuum in the cylinder is reduced to 4000 pa or less, It is another object of the present invention to provide a method for melt-spinning a powder-containing polyester, which comprises spinning while discharging moisture from a discharging mechanism.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The present invention is to produce a polyester fiber containing powder at 5.0% by weight or less based on the weight of the fiber. Examples of the polyester to which the powder is added include polyalkylene terephthalate and polyalkylene naphthalate. Is polyethylene terephthalate (PE
T) and polybutylene terephthalate (PBT) are preferred. In addition, the polyalkylene terephthalate may contain a copolymer component as long as it is in a small amount. Examples of the copolymer component include aromatics such as 5-sodium sulfoisophthalic acid, isophthalic acid, phthalic anhydride, and dicarboxylic naphthalate. Dicarboxylic acid components, aliphatic dicarboxylic acid components such as adipic acid and sebacic acid, glycol components such as diethylene glycol, propylene glycol, 1,4-cyclohexanedimethanol, pentaerythritol, and alkylene oxide adducts of bisphenol S, 4-hydroxybenzoic acid And hydroxycarboxylic acid components such as ε-caprolactone.

The powder to be contained in the polyester is a powder containing a large amount of water, and is a compound having water of crystallization or having a hygroscopic property due to its porous crystal structure. In such a case, the production method of the present invention is effective. In particular, when the water content of the powder is 500 ppm or more, the viscosity of the polymer is reduced due to the effect of the water brought in by the powder as described above. Therefore, it is effective when a powder having a water content of 500 ppm or more is used. .

Specific examples of such a powder include an antibacterial agent such as silver zeolite, a substance for imparting hygroscopicity such as magnesium sulfate, and a deodorant such as aluminum polyphosphate and metal phthalocyanine. Particularly, the master chip method is effective for silver zeolite and magnesium sulfate in which the viscosity of the polymer tends to decrease.

The amount of powder contained in the polyester is as follows:
It must be less than 5.0% by weight based on the weight of the fiber. If the amount of the powder exceeds 5.0% by weight, the polymer viscosity decreases during spinning due to the moisture contained in the powder, so that the operability is remarkably reduced, and the resulting fiber is inferior in high elongation, etc. Coloring occurs.

Next, the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing one embodiment of a twin-screw extruder used in the present invention. According to the present invention, twin-screw extrusion includes a polymer supply zone 3, a vacuum kneading zone 4, and an extrusion zone 5 inside the cylinder, and a discharge mechanism (not shown) for discharging water from the cylinder in the vacuum kneading zone 4 to the outside of the system. Melting and spinning are performed using a machine. First, the polymer is supplied to the polymer supply zone by measuring and adjusting the polymer by the polymer chip supply device 1 and the powder by the powder supply device 2 provided in the polymer supply zone 3 so that the content of the powder is constant. I do. Then, while melting and kneading with a screw in a cylinder in a vacuum kneading zone 4 provided with a vacuum sealing ring 7 and the like, the pressure is reduced by a vacuum pump 6 and the like.
The water in the polyester is separated from the powder, and the water in the cylinder is discharged out of the system by the discharge mechanism. The molten polymer containing the powder from which water has been removed in this way is extruded from the extrusion zone 5, and is spun through a booster pump 8, a lightweight pump 9, and a spin beam 10, and spinning is performed.

The method of the present invention is effective when powder having a water content of 500 ppm or more is used. However, the upper limit of the water content is preferably 5000 ppm or less, and the water content of the powder is 5000 ppm or less. When it exceeds, it becomes difficult to separate the water sufficiently and to discharge it to the outside of the cylinder. Normally, when a powder containing water is added to a polymer, the powder is added after drying, but according to the present invention, the drying step can be omitted.

When discharging the water separated in the vacuum kneading zone, it is necessary to reduce the degree of vacuum in the cylinder to 4000 Pa or less. If it exceeds 4000 Pa, the water separated from the polyester cannot be sufficiently discharged, so that the viscosity of the polymer is reduced and the physical properties of the resulting fiber become insufficient.

Further, in the present invention, the ratio Q / N between the discharge amount Q (kg / h) of the twin-screw extruder and the rotation speed N (rpm) of the screw in the cylinder is set to 0.1 to 1.0. Is preferred. If the ratio is less than 0.1, the number of revolutions becomes too high, and the polyester generates heat and tends to be thermally decomposed. If it exceeds 1.0, the balance between supply and extrusion is lost, and the sealing performance under reduced pressure is liable to deteriorate.

The screw specifications of the twin screw extruder are as follows:
It is not particularly limited, such as different directions, co-rotating and non-meshing, partially meshing, completely meshing type.

In the method for melt-spinning polyester fibers of the present invention, a twin-screw extruder equipped with a discharge mechanism for discharging water from a cylinder in a vacuum kneading zone to the outside of the system can be used to remove water during the fiber production process. Therefore, even if a powder containing a large amount of water and thus difficult to produce by the master chip method is used, the physical properties of the fiber are not reduced, the coloring is not caused, and the operability is good, and the polyester fiber containing the powder is excellent. Can be obtained.

[0020]

Next, the present invention will be described specifically with reference to examples. The measurement of various characteristic values in the examples was performed as follows. (A) Intrinsic viscosity [η] Measured at a temperature of 20 ° C. using an equal weight mixture of phenol and ethane tetrachloride as a solvent. The viscosity retention was determined by the following equation. Viscosity retention (%) = (B / A) × 100 A: Intrinsic viscosity of polymer chip before kneading with powder B: Intrinsic viscosity of fiber obtained after winding (b) Strong elongation Orientec The measurement was performed using a Tensilon UMT-4-100 model at a sample length of 50 cm and a tensile speed of 50 cm / min. (C) Water content The water content of the powder to be added was measured using an MCC trace water content measuring device (manufactured by Mitsubishi Chemical Corporation). Moisture content is 1g of sample
Is heated to 300 ° C to react the generated water with the titrant,
It was calculated by potentiometric titration. (D) Operability The number of yarn breaks per day during spinning is 3 per spindle.
When less than 6 times, it was evaluated as ○, when 3 to 6 times, Δ, and when more than 6 times, as ×. (E) Coloring of Fiber The coloring of the obtained fiber was visually determined.

Example 1 Intrinsic viscosity: 0.69, glass transition temperature: 77 ° C., crystallization temperature: 12
A PET chip having a melting point of 5 ° C, a melting point of 259 ° C, and a water content of 2000 ppm was twin-screw extruder TBX-30 manufactured by Nippon Steel Works (with a discharge mechanism,
(Specification of screw: co-rotating complete meshing type) A powder zeolite having a moisture content of 835 ppm (antibacterial agent: Zeomic, manufactured by Shinagawa Fuel Co., Ltd.) was used as a powder by a powder supply device provided in the polymer supply zone so as to be 1.0% by weight based on the fiber weight. After weighing, it was fed to the polymer feed zone in the cylinder. Then, PET and powder were kneaded at a cylinder temperature of 260 ° C. and a screw rotation speed of 15 rpm, and the degree of decompression in the cylinder when separating water in the powder was set to 1350 pa. Extrusion was performed at an amount of 2.5 kg / h, and melt spinning was performed. The spun yarn is wound up at 3500 m / min.
A d / 24f semi-undrawn yarn (POY) was obtained. Evaluation of operability, intrinsic viscosity of obtained fiber (POY), viscosity retention,
Table 1 shows the results of the elongation and coloring.

Examples 2 and 3 and Comparative Examples 1 and 2 The same procedure as in Example 1 was carried out except that the content of the powder and the degree of reduced pressure in the cylinder were changed as shown in Table 1. Table 1 shows the results of the evaluation of operability and the intrinsic viscosity, viscosity retention, high elongation, and coloring of the obtained fiber (POY).

Examples 4-6, Comparative Examples 3-4 The powder was changed to magnesium sulfate having a moisture content of 687 ppm (hygroscopic agent: Tomix, manufactured by Tomita Pharmaceutical Co., Ltd.), the content of the powder, and the The procedure was performed in the same manner as in Example 1 except that the degree of reduced pressure was changed as shown in Table 1. Table 1 shows the results of the evaluation of operability and the intrinsic viscosity, viscosity retention, high elongation, and coloring of the obtained fiber (POY).

[0024]

[Table 1]

As is evident from Table 1, in Examples 1 to 6, melt spinning was performed with good operability without yarn breakage, and there was almost no decrease in the viscosity of the polymer. It had excellent elongation and no coloring.
On the other hand, in Comparative Examples 1 and 3, since the amount of the powder added exceeded 5.0% by weight, the viscosity of the polymer was reduced due to the moisture contained in the powder, the operability was poor, and the obtained fibers had high elongation characteristics Inferior, coloring had occurred. In Comparative Examples 2 and 4, since the degree of decompression in the cylinder was 4000 pa or more, water was not sufficiently discharged, the viscosity of the polymer was reduced, and the yarn was frequently broken during melt spinning and could not be wound. .

[0026]

According to the present invention, even when a powder containing a large amount of water is melt-mixed with a fiber-forming polymer and spinning is performed, physical properties such as coloring and high elongation are not reduced. It is possible to obtain polyester fibers having excellent physical properties with good operability.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of a twin-screw extruder used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polymer chip supply apparatus 2 Powder supply apparatus 3 Polymer supply zone 4 Decompression kneading zone 5 Extrusion zone

Claims (2)

[Claims] 1. A twin-screw extruder comprising a polymer supply zone, a vacuum kneading zone, and an extrusion zone in the cylinder from the upstream side, and having a discharge mechanism for discharging water from the cylinder in the vacuum kneading zone to the outside of the system. When melt-spinning polyester fiber containing powder of 5.0% by weight or less based on the fiber weight, powder having a water content of 500 ppm or more is supplied to the polymer supply zone, and the molten polymer is melted by a screw in a cylinder in a vacuum kneading zone. And the water in the powder is separated, and the degree of decompression in the cylinder is reduced.
A method for melt-spinning a powder-containing polyester, comprising reducing the pressure to 4000 pa or less and spinning while discharging water from a discharging mechanism. 2. The method according to claim 1, wherein the powder is silver zeolite particles or magnesium sulfate.