KR20020003451A - A process of preparing for the polyester yarn - Google Patents

Abstract

PURPOSE: A process of preparing the titled polyester fiber capable of effectively retarding crystallinity that suddenly increases during spinning at a high wind-up speed is provided, which improves productivity, has improved workability such as spinning and false twisting and can prevent degradation of quality of a yarn and omit a drying process of an orientation inhibitor. CONSTITUTION: The polyester fiber is prepared by melt spinning of a polyester polymer, wherein 0.5 to 5.0% by weight of an orientation inhibitor is uniformly mixed with a polyester polymer in a molten state to produce a mixed solution, which is repeatedly masticated in a stationery type mixer disposed at a position in which the mixed solution is separated or at the back of a curve type flow channel of channels of the mixed solution connected to a spinning pack, spun and winded up at a speed of 4,000m/min or more. The glass temperature of the orientation inhibitor is 100deg.C or more.

Description

Process for preparing polyester fiber {A process of preparing for the polyester yarn}

The present invention relates to a method for producing a polyester fiber that can effectively delay the phenomenon that the crystallization on the radiation sharply increases when the high-speed spinning of the polyester fiber.

When spinning a polyester polymer at a high speed of more than 4,000m / min, the phenomenon of "Spinning Crystallinity" occurs due to the rapid increase in the radial tension, which causes severe process instability factors such as cutting and moor. The sex is significantly lowered. As a result, when spinning the polyester fiber, there is a limit of spinning speed, and currently the mass production of polyester partial alignment yarns is usually produced at spinning speeds of 3,500 to 4,000 m / min.

At the spinning speed of 4,000m / min as the critical point, the increase in molecular orientation increases without increasing the crystallinity, but when the spinning speed exceeds 4,000m / min, the molecular orientation and crystallinity increase simultaneously. Therefore, as the spinning speed increases, the crystallinity increases rapidly with the increase in the radiative force and the orientation crystallization accordingly. As the spinning speed increases, the density and birefringence also increase. Ziabicki and H. Kawai Edited, 'High Speed Fiber Spinning', John Wiley & Sons, New York, 1985].

Until now, the process of delaying the rapid increase of the crystallization on the radiation by increasing the spinning speed in the polyester fiber production process overcomes the existing limit spinning speed and spins the polyester partial alignment yarn at a high speed of 4,000 m / min or more. Much research has been conducted on. Known methods to date can be roughly classified into first, through the modification of the raw polymer (copolymerization, molecular chain crosslinking, etc.) and second, by mixing the polymer material.

As a first method, EP 0 263 020 and US Pat. No. 4,518,744 add compounds pentaerythrite, trimethylropropane, melitic acid and trimellitic acid, which have side chains to the molecular chain, before or after transesterification or polymerization. US Patent 4,966,740 proposes a method for adding tetraethyl silicate before or after the transesterification reaction, US Patent 4,092,299 proposes a molecular chain crosslinking method using a tetrafunctional material have. However, the first methods must specifically select the polymerization conditions, and the workability in the draw combustion process is lowered. In particular, the high cutting rate in the combustion process causes a problem of difficult combustion.

As a second method, US Pat. No. 4,609,710 discloses a method of mixing polystyrene, polyamide, polymethylmethacrylate, or the like as a molecular alignment regulator during or after the polymerization of a polyester. In addition, a method of reducing the radiation orientation by adding a small amount of liquid crystal polymer material, polyethylene, polyethylene glycol, etc. in the conventional polyester polymerization is known. Appl. Polym. Sci., 31 , 2753 1986)]

In this case, the flowability of the polymer melt in the spinning process is drastically changed, which greatly affects the spinning characteristics, in particular, the spinning speed, thereby lowering the spun orientation. However, the method is difficult to spin stably due to the problem of uniformly mixing the added polymer, and the mixed polymer is moved to the fiber surface in the drawing and burning process to inhibit the workability, the occurrence of wool and fine dye stains Occurrence is a cause of deterioration of the final false twist quality.

The present invention is to provide a method for producing a polyester fiber that can effectively delay the phenomenon of the rapid increase in crystallization on the radiation when spinning the polyester fiber at a winding speed of 4,000m / min or more. In addition, the present invention is excellent in the workability of spinning, stretching, and flammability, by mixing the polymer and the crystal orientation inhibitor more uniformly, it is possible to prevent the crystal orientation inhibitor to move to the fiber surface to reduce the yarn quality, 4,000m / It is an object of the present invention to provide a method for producing a polyester partial alignment yarn at a winding speed of more than one minute.

The method for producing a polyester fiber of the present invention for achieving the above object, when producing a polyester fiber by melt spinning the polyester polymer, 0.5 to 5.0% by weight of the crystal orientation inhibitor in a twin screw extruder in the molten state The mixture is uniformly mixed with the ester polymer to prepare a mixed melt thereof, and then a kneading mixer is repeatedly kneaded by arranging a stationary kneader immediately after the point where the mixed melt is branched from the flow path of the mixed melt connected to the spin pack or immediately after the curved flow path. And it is characterized by spinning, winding at a speed of 4,000m / min or more continuously.

Hereinafter, the present invention will be described in detail.

First, the present invention mixes 0.5 to 5.0% by weight of a crystal orientation suppressor of a thermoplastic resin having a glass transition temperature of 100 ° C. or higher in a twin screw extruder, and prepares a mixed melt thereof by mixing with a polyester polymer in a molten state. As the crystal orientation suppressor, polymethyl methacrylate resin, polystyrene resin, or methyl methacrylate-styrene copolymer resin is used.

The glass transition temperature (Tg) of the crystal orientation suppressor is 100 ° C. or more. The reason is to maintain the difference in the solidification behavior of the polyester polymer having a glass transition temperature (Tg) of 80 ° C. on the radiation and the crystallization inhibitor, thereby suppressing the crystal orientation behavior of the polyester polymer.

If the glass transition temperature (Tg) of the crystallization inhibitor is less than 100 ℃, the difference in the solidification behavior between the polyester polymer and the crystallization inhibitor is small, it is difficult to effectively suppress the crystal orientation behavior of the polyester polymer on the radiation. As a result, the winding speed cannot be made higher than 4,000 m / min.

Due to the attractive force between the aromatic ring included in the crystallization inhibitor and the aromatic ring included in the polyester molecule, it is possible to more effectively inhibit the orientation crystallization occurring during the spinning and stretching process. It is well known that an aromatic ring is composed of double bonds between constituent carbon atoms, and therefore, an attractive force exists between adjacent aromatic rings.

In addition, the aromatic part is a rigid part inside the molecular chain, while the aliphatic part means a flexible part. Therefore, the presence of an appropriate aromatic part can maintain the mechanical properties of the polymer chain, a crystallization inhibitor, thereby minimizing the loss of mechanical properties, such as a decrease in strength by the crystallization inhibitor fibrils distributed in the polyester. .

From this point of view, by using the crystallization inhibitor of the present invention, it is possible to maintain a similar level of physical properties, particularly strength, to the polyester partial-orientated yarn prepared by the general method.

The amount of the crystallization inhibitor added is 0.5 to 5.0% by weight based on the weight of the entire polymer (polyester polymer + crystallization inhibitor). If the added amount is less than 0.5% by weight, the effect of suppressing radiocrystallization is insignificant, and when the added amount is more than 5.0% by weight, the stretching and flammability processability deteriorate.

In the present invention, the polyester chips are first supplied to the extruder and melted, and then the molten polyester is fed to a two-stage twin screw extruder, and at the same time, the crystallization suppressor chip is supplied thereto to melt and mix them. do. More preferably, the melt mixed in the two-stage twin screw extruder is continuously kneaded with a stationary kneader.

The stationary kneader serves to make the crystal orientation suppressor distribution more uniform in the melt. In the case of the present invention, since more uniform kneading is required, it is preferable to pass a stationary kneader of 20 stages or more. In other words, kneading of 1 million (2 ²⁰ ) times or more is possible to uniform distribution of crystallization inhibitors, and is preferable to prevent the occurrence of salt spots in the false twisted state of the final product.

Otherwise, if the stationary kneader of less than 20 stages is adopted, deterioration of the quality may occur due to the occurrence of fine salt spots in the twisted yarn state, deterioration of workability in the stretching and combustion process, and stable workability There is a possibility of becoming difficult.

Next, the polyester polymer and the crystallization inhibitor are melted and mixed uniformly as described above to prepare a mixed melt, and then, immediately after the point where the mixed melt is branched from the flow path of the mixed melt connected to the spin pack or immediately after the curved flow path, A kneader is placed to knead the mixed melt repeatedly. Each stationary kneader used at this time is preferably 3 to 5 stages.

The total length of the stationary kneader disposed in the flow path of the mixed melt connected from the extruder to the spin pack is 5-15% of the total length of the flow path. If the total length of the stationary kneader is less than 5% of the total length of the flow path, the mixing of the mixed melt may be insufficient, and if the total length exceeds 15%, the polymer residence time may be too long and the yarn property may be deteriorated.

When the mixed melt passes through a branching point or a curved flow path, centrifugal force is applied to cause the same type of polymers to aggregate together. The present invention is characterized by kneading the mixed melt more evenly by placing a stationary kneader immediately after the portion where such a phenomenon occurs.

Next, the mixed melt is spun and wound continuously at a speed of 4,000 m / min or more. The take-up speed increases productivity by 40% at least 4,000 meters per minute. Winding speeds of less than 4,000m / min have little productivity gains, so there is no economic benefit in terms of return on facility investment.

In addition, the elongation at break of the partial oriented yarn wound at a speed of 4,000 m or more per minute was 120% or more. When the elongation is more than 120% crimp frequency (Crimp Frequency) is high, the crimp quality can be obtained good twisted yarn, it is possible to secure excellent flammability workability. Otherwise, it is difficult to perform high-speed operation more than 800 meters per minute in the simultaneous drawing and burning process, and it is difficult to obtain the same twisted yarn with the same physical properties as in the case of the simultaneous drawing and burning of the unstretched yarn spun at ordinary 3,000 to 3,500 meters per minute. It is difficult to secure the stability of the work by obtaining the combustible yarn with reduced varnish (Crimp Liveliness).

In the present invention, it is preferable to maintain the shear rate in the spinneret during spinning at 7,000 to 15,000 per second. The shear rate in the spinneret during spinning is the dominant factor that determines the radial distribution of the crystallization suppressor distributed inside the spun yarn. If the shear rate is low, the degree of orientation of the crystallization inhibitor in the fiber axis direction is lowered, which may cause a problem that the effect of suppressing the orientation crystallization of the polyester fiber is reduced. On the other hand, if the shear rate is too high, The problem that the distribution is concentrated on the surface portion of the fiber occurs, which may cause a problem of lowering the strength.

Therefore, if the shear rate in the spinneret is maintained within the range of 7,000 or more and 15,000 or less per second, the effect of suppressing the orientation crystallization of the polyester fiber is sufficiently exerted, and the distribution of the crystallization suppressor in the radial direction of the fiber is appropriately maintained and partially aligned. The strength of the yarn and the false twisted yarn can be maintained properly.

The polyester fiber of the present invention prepared as described above is 95 to 99.5% by weight of the main polyester and the polymethyl methacrylate resin, polystyrene resin or methyl methacrylate-styrene copolymer resin 0.5 Consists of ~ 5.0% by weight, the elongation at break is more than 120%.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited only to the following examples.

Example 1

Polyethylene terephthalate having an intrinsic viscosity of 0.64 was dried at 155 ° C. for 4.5 hours. After melting the chip with a melt extruder, a continuous screw extruder having a glass transition temperature of 105 DEG C and 0.9% by weight of methyl methacrylate / styrene-based copolymer and 91.1% by weight of the polyethylene terephthalate melt (35 mm diameter twin screw extruder (temperature 300 ° C.). In addition, the fine kneading was continuously passed through a 20-stage stationary kneader.

Also, the mixed polymer melts are disposed at the point where the polymer melt is branched in the flow path in the polymer melt, and after the curved flow path, a stationary kneader (total length of the stationary kneader to the total length of the flow path: 7%) is disposed. After the discharge hole was spun through the punched spinneret, a 22 ° C. cooling air was sent at a rate of 0.5 m per second to cool and solidify, followed by a take-up roller, and then wound to prepare a polyester partial alignment yarn. At this time, the shear rate in the spinneret was 9,000 per second and the winding speed was 4,200 m / min.

The twisted yarn was manufactured using the Murada 33H (manufactured by Japan Murada Co., Ltd.) draw-synchronous combustor. The burning rate was 850 m / min, the drawing ratio was 1.671 times, the temperature of the first heating plate was 200 ° C., the angle between the nip belts was 105 degrees, and the speed ratio was 1.5.

The final false twisted yarn was circular knitted using a circular knitting machine, and then dyed at 130 ° C. for 60 minutes using a disperse dye, and then dyeing quality of the plaque was examined. Table 2 shows the results of evaluating the fairness of spinning and combustibility and the properties of partially aligned yarns and combustible yarns.

Example 2 to Example 6 and Comparative Example 1 to Comparative Example 2

Except for changing the resin type of the crystallization inhibitor, the glass transition temperature of the crystallization inhibitor, the mixed weight% of the crystallization inhibitor, the winding speed and the ratio of the total length of the stationary kneader to the total length of the flow path of the polymer melt as shown in Table 1 Polyester partial orientation yarn, false twisted yarn and circular knitted fabric were prepared under the same process and conditions as in Example 1. Table 2 shows the results of evaluating the fairness of spinning and combustibility and the properties of partially aligned yarns and combustible yarns.

Polyester partial alignment yarn manufacturing conditions division Stationary Kneader Total Length Ratio Crystallization Inhibitor Properties Winding speed (m / min) Resin type Glass transition temperature (℃) Addition amount (% by weight) Example 1 7% Methyl methacrylate-styrene copolymer 105 0.9 4,200 Example 2 10% Methyl methacrylate-styrene copolymer 105 2.5 4,500 Example 3 6% Polymethyl methacrylate 106 1.5 4,800 Example 4 13% Polymethyl methacrylate 106 3.5 4,300 Example 5 9% polystyrene 107 2.9 4,300 Example 6 14% polystyrene 107 4.0 4,100 Comparative Example 1 0% - - - 4,500 Comparative Example 2 20% Polymethyl methacrylate 106 0.1 4,200

Workability and Yarn Property Evaluation Results division Radiation workability Partial Alignment Elongation (%) Combustible Workability Primp Quality Platter Cream Rigidity (%) Example 1 Good 125 Good 41 none Example 2 Good 132 Good 38 none Example 3 Good 138 Good 39 none Example 4 Good 143 Good 42 none Example 5 Good 147 Good 44 none Example 6 Good 123 Good 43 none Comparative Example 1 Bad 83 Bad 28 has exist Comparative Example 2 Bad 110 Bad 29 has exist

The present invention can effectively delay the "radiation crystallization" in which the crystallization on the radiation is rapidly increased during high-speed radiation to produce a polyester partial alignment yarn at a winding speed of 4,000m / min or more. As a result, productivity is improved. In addition, the present invention is uniformly mixed with the polyester polymer and the crystal orientation inhibitor which is a crystal orientation inhibitor excellent in drawing and flammability processability. In addition, the present invention can effectively prevent the phenomenon that the crystal orientation inhibitor is moved to the yarn surface to reduce the yarn quality.

Claims (4)

In manufacturing polyester fiber by melt spinning polyester polymer, 0.5 ~ 5.0 wt% of crystal orientation suppressor is uniformly mixed with polyester polymer in molten state in a twin screw extruder to prepare a mixed melt thereof, and then spin pack The mixing melt is repeatedly kneaded by placing a stationary kneader at the point where the mixed melt is branched or immediately after the curved flow path among the flow paths of the mixed melt connected up to and continuously spinning and winding at a speed of 4,000 m / min or more. The manufacturing method of the polyester fiber. The method for producing a polyester fiber according to claim 1, wherein the crystallization inhibitor is a polymethyl methacrylate resin, a polystyrene resin or a methyl methacrylate-styrene copolymer resin. The method of claim 1, wherein the total length of the stop kneader disposed in the flow path of the mixed melt connected to the spin pack is 5 to 15% of the total length of the flow path. The method for producing a polyester fiber according to claim 1, wherein the crystallization inhibitor has a glass transition temperature of 100 ° C or higher.