JPH0617317A - Production of polyester fiber - Google Patents

Abstract

PURPOSE:To obtain the subject fiber having excellent strength, elongation and heat-resistance by mixing a non-compatible polymer to a polyethylene terephthalate, etc., spinning the mixture in molten state, cooling the spun filament to the glass transition temperature or below, drawing and heat-treating in a hot zone and taking up at a high speed. CONSTITUTION:A polyester containing ethylene terephthalate unit as the main constituent component (e.g. polyethylene terephthalate) is mixed with 0.5-7wt.% of a non-compatible polymer (e.g. polymethyl methacrylate) and the obtained polyester composition is melt-spun through a spinneret and temporarily cooled to a temperature below the glass transition temperature of the polyester. The cooled filament is passed through a hot zone to reheat the filament at a temperature above the glass transition temperature and below the melting point of the polyester to effect the drawing and heat-treatment of the filament and finally taken up with a 1st take-up roll at a take-up speed of >=6,000m/min to obtain the objective polyester fiber having excellent strength, elongation, heat-resistance and spinnability in remarkably improved productivity.

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 by a high speed spinning method, and more particularly to a method for producing a polyester fiber having excellent physical properties by a hot tube draw spinning method.

[0002]

2. Description of the Related Art Polyester fibers, particularly polyethylene terephthalate fibers, are widely used for clothing and industrial applications because of their excellent heat resistance, chemical resistance and mechanical properties. A typical polyester fiber for clothing having a single yarn denier of about 2 to 3 denier is formed by extruding a melted polyester into a fibrous form from a spinneret and then forming a fiber of 1000 to 3500.
It is manufactured through a two-step process of once winding at a take-up speed of m / min, and then spinning and drawing in which drawing and heat setting are performed.

In recent years, a high-speed spinning method has been developed for the purpose of improving productivity, in which a fiber which can sufficiently satisfy practical characteristics can be obtained without passing through 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 spun from the spinneret is directly drawn at 5000 m / min or more without reheating, and after being cooled and solidified, the fiber is heated in a heating atmosphere such as a hot tube. Stretching heat treatment while reheating, hot tube stretching and spinning method to take off at 4000 m / min or more, after taking up with the first take-up roll, then the second
There is a direct spinning drawing method in which drawing is performed between the drawing roll and a drawing roll and the drawing is performed at 3000 m / min or more. These high-speed spinning methods are expected to reduce costs such as equipment simplification, space saving, energy saving, and reduction of required personnel by eliminating the need for the conventional drawing process, and the take-up speed is greatly improved. Therefore, it is expected that productivity will be significantly improved.

Of these, the hot tube draw-spinning method does not cause a rapid change in the yarn speed immediately below the spinneret as compared with the ultra-high-speed spinning method, resulting in less yarn breakage, and the conventional two-step spinning / drawing process. There is an advantage that a fiber having substantially the same physical properties as that of the drawn yarn after passing is obtained.

Also, compared with the direct spinning and drawing method, there is an advantage that the number of rolls can be reduced and the use of heating rolls is not necessary, and the production can be performed at low cost.

As described above, the hot tube draw spinning method is
It can be said that this is an excellent spinning method in the high-speed spinning method. However, when the take-up speed is increased to further improve productivity, necking deformation peculiar to high-speed spinning occurs above the heating zone in the hot tube draw spinning method, and the yarn speed at the inlet of the heating zone is increased. It has become clear that is rapidly increasing. For this reason, yarn breakage frequently occurs, and the yarn formability is remarkably deteriorated, and productivity is reduced rather than improved.

Further, when the yarn speed at the inlet of the heating zone becomes 4500 m / min or more as a result of increasing the take-up speed, oriented crystallization proceeds in the cooling process, and thus the fiber obtained by the ultrahigh-speed spinning method. The structure becomes similar to that of the conventional drawn yarn, and the advantage of the hot tube draw-spinning method that the physical properties are obtained is almost eliminated.

For this reason, the currently adopted 4
It has been difficult to spin by a hot tube stretch spinning method over a take-up speed of about 500 to 5,500 m / min, which has been one of the technical barriers.

By using this hot tube draw spinning method,
There are several examples in which the take-up speed is increased to 6000 m / min or more. JP-A-51-147613
In the gazette, the yarn is divided to separate the entrained airflow, and the draw ratio is kept low and the heating zone inlet speed is increased to increase the tension of the yarn entering the heating zone to prevent the yarn shaking and the disorder of the yarn path. I tried to hold it down as much as possible. Therefore, in this publication, when the take-up speed is 6000 m / min, the heating zone inlet speed is 4500 m / min or more, that is, about 4600 m.
/ Min to 5700 m / min. When normal homopolyethylene terephthalate is applied to this process, the heating zone inlet speed is usually at this level, and at this rate, necking substantially occurs above the heating zone, and as described above, In addition, not only the physical properties similar to those of the conventional drawn yarn cannot be obtained, but also the yarn breakage frequently occurs and the yarn-forming property is deteriorated. These behaviors are essential problems of homopolyethylene terephthalate as described above, and it is difficult to overcome them by changing the spinning conditions.

Further, in Japanese Patent Publication No. 58-3049, a heating zone at a temperature higher than the melting point of the polymer is provided directly under the spinneret, and the cooling and reheating temperatures of the yarn are controlled so that the yarn can be collected at 6000 m / min or more. Is proposed. However, this method requires two heating devices because two heating zones having different temperatures are required, and thus the device is large and complicated. Further, the modification work for removing the dirt generated on the surface of the mouthpiece and the maintenance management become complicated. In addition, since the atmosphere directly under the spinneret is extremely hot, the sublimation of decomposed products from the discharged polymer becomes violent, which causes dirt on the spinneret surface and deterioration of the longitudinal direction of the yarn and the uniformity between single yarns. Invite. Further, in this method, since the reheating treatment is performed after the filaments are bundled, the heat applied between the single yarns is likely to be non-uniform, and heat treatment unevenness is likely to occur.
As described above, the speedup of the hot tube stretch-spinning method up to now has been studied only by changing the spinning method, and few have tried to speed up by actively changing the polyester component to be spun. Moreover, the improvement effect was not sufficient.

On the other hand, in the ultra-high-speed spinning method, a method of copolymerizing paraoxybenzoic acid with polyester is attempted in an attempt to increase the speed by changing the polyester component (JP-A-59).
-47423), a method of adding a polymer such as polymethylmethacrylate (JP-A-62-21817), and a method of copolymerizing bis (4-carboxyphenoxy) ethane (JP-A-63-190015). Gazette) is proposed. However, from the viewpoint of securing stable production for a long period of time, these methods cause yarn breakage several times in an extremely short time in terms of spinnability and yarn breakage during winding a small amount of product. However, it is hard to say that the thread-forming property is sufficient. Further, JP-A-63-59412 proposes a method of using a polyester mainly composed of polytrimethylene terephthalate, polytetramethylene terephthalate, or polyhexamethylene terephthalate having an intrinsic viscosity of 1.0 or less. In comparison with polyethylene terephthalate, there is a lack of balance of properties as a fiber for clothing, and there is a problem in cost,
In fact, it is impossible to substitute polyethylene terephthalate.

It is considered that such a problem of the spinnability is caused by the rapid thinning deformation in the cooling process peculiar to the ultra high speed spinning method as described above.

[0013]

The object of the present invention is to produce a polyester fiber having excellent mechanical properties, particularly strength, of the obtained fiber even in a very high productivity ultra-high-speed spinning region having a take-up speed of 6000 m / min or more. Another object of the present invention is to provide a hot tube stretch spinning method.

Another object of the present invention is to produce a polyester fiber at a high speed, which has a stable yarn quality, high productivity and excellent spinnability without being broken even when taken at a higher take-up speed than before. Is to provide a method.

[0015]

The object of the present invention is to prepare a polyester composition prepared by mixing 0.5 to 7% by weight of an incompatible polymer with a polyester having ethylene terephthalate units as a main constituent from a spinneret. After melt spinning and once cooling to below the glass transition temperature of the polyester,
Characterized in that the yarn is made to run in a heating zone, the yarn is reheated to a temperature not lower than the glass transition temperature of the polyester and not higher than a melting point to be subjected to a stretching heat treatment, and is taken up by a first take-up roll having a take-up speed of 6000 m / min or more. It can be achieved by the method for producing polyester fiber.

The present invention will be described in detail below. The greatest feature of the present invention is that the main constituent is a polyester composition obtained by adding and mixing a specific polymer to the polyester having an ethylene terephthalate unit as a polyester raw material in the hot tube drawing and spinning method, thereby providing excellent physical properties and homogeneity. Without impairing the spinnability of the yarn that has,
The point is that it can be obtained at an ultra high speed of 6000 m / min or more.

In the hot-tube stretch-spinning method, in the case of homo PET, when the speed is increased to 6000 m / min or more, necking deformation is already generated above the heating zone as described above, and the yarn speed is 4500 m / min. With the above high speed, the physical properties of the fiber are changed to the physical properties peculiar to ultra-high-speed spinning with low strength, high elongation and low orientation, whereas when the polyester composition of the present invention is used, it is added and mixed. The specific polymer component increases the flexibility of the molecular chain and makes it difficult to orient during the spinning cooling process.Therefore, even if the take-up speed is increased, the yarn speed at the hot tube inlet can be suppressed to the conventional speed. Because you can. by this,
Even at a higher speed, it is possible to obtain a yarn whose strength, elongation and orientation are on par with those of a conventional drawn yarn.

Examples of the incompatible polymer used in the present invention include vinyl polymer, polyamide, polyurethane,
Examples include polycarbonate. The vinyl polymer is a polymer obtained by polymerizing a vinyl monomer, for example, a polymethacrylate polymer, a polystyrene polymer, etc., and the polyamide is a polymer having an amide bond, for example, nylon 6, nylon 66 or the like. Above all,
A polymer that reacts with the polyester in a molten state may cause a reaction during melt spinning to lower the physical properties, so a non-reactive polymer is preferable as the polymer to be added,
For example, vinyl polymers are preferred in the above examples.

If the amount to be added and mixed is less than 0.5% by weight, the effect of the present invention cannot be obtained, so it is preferable to mix 0.5% by weight or more. If it exceeds 7% by weight, the ballasting effect immediately after spinning the spinneret in the melt spinning becomes large, the yarn breakage easily occurs, and the spinnability is deteriorated, which is not preferable. For that reason, it is more preferable that the content is 0.5% by weight or more and 5% by weight or less.

The polyester used in the present invention is mainly a polyester having an ethylene terephthalate unit as a constituent component, but other copolymerization components may be copolymerized within the range of 7 mol% or less.

Further, the polyester of the present invention requires various additives such as matting agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents and fluorescent brightening agents. It may be copolymerized or mixed depending on the above.

The polyester composition used in the present invention is
For example, it can be obtained by adding an incompatible polymer to polyethylene terephthalate obtained by a usual method and kneading with an extruder.

The polymer to be added must be an incompatible polymer which is dispersed in the polyester in an incompatible state, and the effect of the present invention can be obtained when the polymer is mixed in the polyester phase. I can't.

The state of being incompatible and mixed means that the mixed components are present as island components (particulates) in the polyester phase as observed by a transmission electron microscope (TEM).

The size of the dispersed phase is preferably 3 μm or less in the molten state before spinning. If it exceeds 3 μm, the ballasting effect in the melt spinning immediately after spinning the spinneret becomes large, the yarn breakage easily occurs, and the spinnability is deteriorated, which is not preferable. For that reason, it is more preferable that the thickness is 1 μm or less.

The polyester composition thus obtained is melt-spun.

First, the polyester melted and discharged from the spinneret is once cooled to a glass transition temperature or lower 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. The distance from the die to the inlet of the heating zone is preferably 0.5 to 4.0 m, and 1.0 to 4.0 in order to give sufficient cooling under the die, workability, and sufficient tension generated by air resistance. 3.0 m is more preferable.

The once cooled yarn is introduced into a heating zone, reheated and drawn and heat treated. In the heating zone, it is preferable that the yarn is not brought into contact with anything other than the yarn path regulating portion at the inlet or the outlet so that the yarn can be freely stretched. The heating cylinder is heated from the surroundings, the hot air introduced by heating, saturated steam or heating steam is filled,
Alternatively, a combination of these is preferably used. In the heating zone, the tension and temperature necessary and sufficient for the passing yarn to undergo the drawing heat treatment are required.

The heating temperature is preferably a temperature at which the fiber retains practical strength and does not cause unevenness in the treatment of the yarn. It is difficult to limit the heating temperature in relation to the draw ratio of the yarn, but in order to cause the stretching, The temperature of the heating zone needs to be 50 to 80 ° C. or higher. Further, 105 ° C. or higher, preferably 110 ° C. or higher is required for more sufficient heat treatment. At this time,
If sufficient heat treatment does not occur even if stretching occurs, the shrinkage rate of boiling water exceeds 30%, resulting in poor dimensional stability. As the upper limit temperature of the heating zone, when the heating temperature reaches a temperature in the vicinity of the melting point of the yarn, the homogeneity between the single yarns in the longitudinal direction of the fiber may deteriorate and it may not be possible to obtain a uniform yarn. The temperature is preferably 250 ° C. or lower, more preferably 200 ° C. or lower from the viewpoint of energy cost.

The stretching heat treatment means that the peak temperature of heat shrinkage stress is 105 ° C. or higher, preferably 110 ° C.
This can be confirmed by the fact that the heat shrinkage stress is 0.3 g / d or more. Stretching heat treatment refers to stretching and subsequent heat treatment. In order for the drawing to occur, the necessary and sufficient tension for drawing is applied to the yarn,
And it is necessary that sufficient heat be supplied from the heating zone. The tension here is (actual tension of the multifilament at the inlet of the heating zone) / (winding yarn denier), such as the single yarn denier of the winding yarn, the take-up speed, and the distance from the spinneret to the heating zone. The tension required for stretching is usually 0.3 g / d or more. If it is less than 0.3 g / d, the stretching becomes insufficient and the mechanical properties deteriorate. The length of the heating zone is preferably 0.5 to 3.0 m from the viewpoint of stable stretching heat treatment and energy cost,
1.0 to 2.0 m is more preferable.

The take-up speed is determined in consideration of the mechanical properties of the obtained fiber, spun yarn breakage, productivity improvement and the like.
In the case of the copolyester of the present invention, if the take-up speed is low, the drawing is insufficient and the birefringence becomes less than 0.13, and it is not possible to obtain fibers satisfying the practical characteristics. Therefore, it is necessary to take it out at least 6000 m / min or more. There is. With the polyester of the present invention, at the above-mentioned take-up speed, a yarn having the same physical properties as the drawn yarn obtained by the conventional method can be obtained, and the productivity of polyester fiber can be improved. When taking into consideration the mechanical properties of the obtained fiber, the demerit of deterioration of the spinnability due to the breakage of spun yarn due to the speed increase, and the merit from the viewpoint of productivity improvement, the take-up speed is 9000 m.
/ Min or less is preferable.

The reason why the physical properties of the fiber obtained by the method of the present invention are excellent even if a high-speed spinning method at a take-up speed of 6000 m / min or more, which is faster than the conventional one, is adopted is incompatible with polyethylene terephthalate. Since the polymer is added and mixed, the polyethylene terephthalate has the effect of lowering the extensional viscosity because slippage occurs at the interface where the polyethylene terephthalate is mixed and the shear rate decreases, which is faster than conventional methods. Even when spinning is performed at the take-up speed, orientation in the spinning cooling process is unlikely to occur, and even when the hot tube stretch-spinning method is performed at a higher speed than conventional, the draw ratio in the heating zone is high, and the heating zone inlet speed is 450.
Since it can be maintained at a low speed of 0 m / min or less, it is considered that a fiber having excellent physical properties and spinnability can be obtained.

[0033]

EXAMPLES Each characteristic value in the examples was determined according to the following method. (A) Strength and Elongation of Fiber It was determined from a load extension curve using a Tensilon tensile tester manufactured by Orientec. (B) Birefringence index The birefringence index Δn = nh was obtained by using an interference microscope (made by Carl Zeiss Co., Ltd.) to determine the refractive index in the direction parallel to the fiber axis (nh) and in the direction perpendicular to the fiber axis (np) from the light passing through the fiber diameter. −np. (C) Spinnability It was evaluated by the average number of yarn breakages when spinning 1000 kg. ◎: When the number of thread breaks is less than 1 ○: When the number of thread breaks is 1 to 3 Δ: When the number of thread breaks is 3 to 5 ×: When the number of thread breaks is 5 or more Example 1, Comparative Example 1 From 75 parts by weight of ethylene glycol and 166 parts by weight of terephthalic acid, a low polymer obtained by a usual esterification reaction was mixed with 0.03% of an aqueous solution of 85% orthophosphoric acid as a coloring inhibitor.
Parts by weight, 0.06 antimony trioxide as a polycondensation catalyst
Parts by weight, 0.06 parts by weight of cobalt acetate tetrahydrate as a toning agent is added to carry out a polycondensation reaction, an intrinsic viscosity of 0.65,
Polyethylene terephthalate having a melting point of 256 ° C. was obtained. This polymer was added and mixed under reduced pressure using a biaxial vent extruder at 280 ° C. while measuring 3% by weight of polymethyl methacrylate having a number average molecular weight of 75,000. When this polyester composition was observed with a transmission electron microscope, polymethylmethacrylate was dispersed in the polyethylene terephthalate phase in a size of about 1 μm. This polyester composition was melted at 290 ° C. and discharged from a die having 24 holes. 25m / min for the yarn discharged from the spinneret,
The yarn was once cooled to room temperature by applying a cooling air of 25 ° C. over a length of 1 m, and then the yarn was introduced into a hot tube having a length of 2.0 m and an inner diameter of 20 mmφ installed 2 m below the spinneret. At this time, the temperature of the inner wall of the hot tube is 200
It was set to ° C. The discharge amount and the take-up speed were changed so that the drawn yarn had a thickness of 50 denier / 24 filament, and a polyester fiber was obtained (Example 1).

A polyethylene terephthalate fiber was prepared by adding polyethylene terephthalate obtained by the same method as described above without adding and mixing polymethyl methacrylate (Comparative Example 1).

The birefringence index (Δn) of each fiber obtained in Table 1
The value, strength, elongation and spinnability were shown.

As is apparent from Table 1, in Comparative Example 1 in which polymethylmethacrylate was not added and mixed, Δn was much lower than the value (0.13 or more) in the conventional drawn yarn at the take-up speed of 6000 m / min or more, The strength and elongation were not the same as those of conventional drawn yarns, and the spinnability was poor. The high-speed spun fiber obtained in Example 1, which is the polyester composition of the present invention, has Δn ≧ 0.13 at a take-up speed of 6000 m / min or more.
The fiber physical properties were practically sufficient for both strength and elongation, and the spinnability was also good.

Examples 2 and 3 Comparative Example 2 In the same manner as in Example 1, 0.5% by weight of polymethylmethacrylate (Example 2), 7% by weight (Example 3),
Melt-spinning was performed from the polyester composition in which 0% by weight (Comparative Example 2) was added and mixed, and the take-up speed was changed in the same manner as in Example 1 to obtain a polyester fiber of 50 denier / 24 filament. Examples 2 and 3 and Comparative Example 2
Table 2 shows the Δn, the strength, the elongation, and the spinnability of the polyester.

In Examples 2 and 3 in which the addition and mixing amount was within the range of the present invention, the effects of the present invention were obtained and the spinnability was good, but the addition and mixing amount was outside the range of the present invention. In Comparative Example 2, the spinnability was lowered.

Examples 4 and 5 Comparative Example 3 A polyester composition (Example 4) in which 3% by weight of polystyrene having an intrinsic viscosity of 0.73 was added to and mixed with polyethylene terephthalate obtained by the same method as in Example 1, A polyester composition containing 3% by weight of nylon 6 having a sulfuric acid relative viscosity of 2.6 (Example 5) and a polyester composition containing 3% by weight of polybutylene terephthalate having an intrinsic viscosity of 0.89 (Comparative Example 3) It was created. When each polyester composition is observed using a transmission electron microscope,
Polystyrene and nylon 6 are about 1 μm and about 0.
Although it had a size of 8 μm and was dispersed in the polyethylene terephthalate phase, polybutylene terephthalate could not be confirmed as a dispersed phase in the polyethylene terephthalate phase.

Melt spinning was performed from these polyester compositions in the same manner as in Example 1 except that the take-up speed was changed.
A polyester fiber of 50 denier / 24 filament was obtained. Δ of polyesters of Examples 4 and 5 and Comparative Example 3
Table 3 shows the n, the strength, the elongation, and the spinnability.

In Examples 4 and 5 in which the incompatible polymer of the present invention was added and mixed, at a take-up speed of 6000 m / min or more, Δ
Although n ≧ 0.13, the effect was seen, but the effect was not seen in Comparative Example 3 in which the compatible polymer was added and mixed.

Comparative Example 4 Polyester fibers were obtained by the usual ultra high-speed spinning method in the same manner as in Example 1 except that the hot tube was not used. The results are shown in Table 4.

The ultra-high speed spinning method resulted in low strength and low orientation, and poor spinnability.

[0044]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[0045]

EFFECTS OF THE INVENTION According to the method of the present invention, even if a high-speed spinning method exceeding the conventional take-up speed is adopted in the hot tube spinning method, the product characteristics are not deteriorated, and the strength and elongation characteristics are excellent, and Since the polyester fiber having excellent heat resistance and yarn-forming property can be provided, the productivity of the polyester fiber can be remarkably improved.

Claims (1)

[Claims] 1. A polyester having a ethylene terephthalate unit as a main constituent and an incompatible polymer of 0.5.
The polyester composition mixed in an amount of ˜7% by weight is melt-spun from a spinneret, and once cooled to a temperature not higher than the glass transition temperature of the polyester, the yarn is run in a heating zone,
The yarn is reheated to a temperature not lower than the glass transition temperature and not higher than the melting point of the polyester and subjected to a stretching heat treatment, and a take-up speed of 6000.
A method for producing polyester fiber, characterized in that the polyester fiber is taken up by a first take-up roll having a rate of m / min or more.