JPH11181624A - Production of polyester fiber and woven or knit fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply produce a spontaneously extensible yarn excellent in quality without any dyeing speck, etc., and useful for clothes applications with good productivity by spinning and directly drawing a polyester under specific conditions. SOLUTION: A polyester is melt spun to provide a yarn having 0.020-0.065 degree of birefringence and the resultant yarn is then drawn without being once wound at 1.01-1.35 draw ratio, <=110 deg.C drawing temperature and >=110 deg.C heat-setting temperature (which is the heat-treating temperature of the yarn after drawing and the temperature of the second hot roller 2HR after the drawing in the case of a hot roller drawing machine) to impart the spontaneous extensibility to the resultant yarn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a swelling, soft,
The present invention relates to a method for producing a polyester fiber which is capable of providing a woven or knitted fabric having an excellent resilience and having less stain spots.

[0002]

2. Description of the Related Art Polyester has various excellent properties including mechanical properties, and is therefore used in various fields including clothing. In clothing applications, quality has been improved targeting natural fibers, but especially as a means to realize a swelling and soft texture.
A so-called shrinkage difference mixed yarn which mixes fibers having different shrinkage characteristics due to heat is widely used. Recently, shrinkage-differential mixed yarns using so-called spontaneously elongated yarns exhibiting extensibility by heat have attracted attention. If this type of shrinkage difference mixed yarn is used, a sufficient difference in yarn length can be obtained after the dyeing process even if the density of the woven fabric increases, and a fabric excellent in swelling and softness can be obtained.

A method for producing a spontaneously elongated yarn is disclosed in, for example,
Japanese Patent No. 352836 discloses a method in which a partially oriented polyester yarn (hereinafter abbreviated as POY) is once stretched and then subjected to a relaxation heat treatment.
Japanese Patent No. 293410 discloses a method in which POY is subjected to a relaxation heat treatment as it is, and generally requires a relaxation heat treatment step. The spontaneously elongated yarn referred to herein is one having a property of being elongated by heat treatment based on the original length before heat treatment. However, with these methods 20-
Since a relaxation heat treatment at a high rate of 50% is required and the process stability is poor, there is a problem in quality such as easy occurrence of yarn spots and occurrence of dye spots. In addition, since the yield is low and the success rate of the processing restart after the doff is low, there is a problem that not only the amount of waste is increased but also personnel for processing the waste are required.

In addition, productivity is low due to low processing speed,
Since a special stretching machine capable of relaxation treatment is required, there is also a problem that equipment costs increase. That is, the cost was high due to these problems.

Also, Japanese Patent Application Laid-Open Nos. 9-228167 and 9-21
No. 060 discloses a method using a fixed-length (tensile) heat treatment of POY. In these methods, however, the yarn sway on a hot plate or a heat setting roller is extremely large, which is also the same as the method using the relaxation heat treatment. Problems arise.

On the other hand, recently, in order to reduce costs by increasing the winding speed and omitting steps, a spinning direct drawing method in which spinning and drawing are directly connected has been widely used. In addition, in the conventional two-step method in which an undrawn yarn is wound once and then subjected to relaxation heat treatment or fixed-length heat treatment, the process becomes unstable due to a change in processing tension due to a temporal change of the undrawn yarn before processing.
Thread spots were a problem. On the other hand, the direct spinning method is excellent in that the above problem can be solved because the undrawn yarn can be processed as it is after spinning, and it is cost effective if the spontaneous elongation yarn can be produced by the direct spinning method. It is also very advantageous in terms of quality as well.

However, as described above, the conventional method for producing spontaneously elongated yarn is generally a relaxation heat treatment and a fixed-length heat treatment, so that it is difficult to apply the method to the direct spinning method in which the yarn speed during processing is high. there were. This is because in the conventional two-step processing, the yarn speed during the relaxation heat treatment or the constant-length heat treatment is 300 m / min or less, while in the direct spinning, the yarn speed is 3 m / min.
Even if the yarn is spun at 000 m / min and relaxed by 40%, the yarn speed becomes 2400 m / min, which is much higher. Then, only by increasing the yarn speed, tension due to inertial force and air resistance is generated.

That is, the relaxation heat treatment must be performed under a much higher tension than in the two-step method. Therefore, 2
The running of the yarn becomes more unstable than in the process method, and even if a non-contact heater is used, the relaxation heat treatment is practically impossible. Even if the relaxation heat treatment can be performed, troubles such as thread breakage and winding around the first hot roller occur frequently, and the operability is further deteriorated, and the cost increase is accordingly enormous. In addition, since the running of the yarn becomes extremely unstable, the yarn spots become large. In addition, not only the heat treatment time is shortened because the yarn speed is high, but also the thermal efficiency is extremely reduced due to the accompanying airflow,
It is necessary to make the temperature of the non-contact heater much higher and longer than in the case of the two-step method, and a large capital investment is required.

[0009]

DISCLOSURE OF THE INVENTION The present invention solves various problems caused by relaxation heat treatment and constant-length heat treatment in the production of spontaneously elongated yarns, and is more productive, simpler and more excellent in the quality of dye spots and the like. And a method for producing a spontaneously elongated yarn.

[0010]

The object of the present invention is to provide a yarn having a birefringence of 0.020 to 0.065 by melt-spinning polyester.
A method for producing polyester fiber, wherein spontaneous elongation is imparted by stretching under conditions that simultaneously satisfy the following requirements without winding up: (1) stretching ratio 1.01 to 1.35 (2) stretching temperature ≦ 110 ° C. (3) Heat setting temperature ≧ 110 ° C or melt-spun polyester to form a yarn with birefringence of less than 0.020, giving spontaneous extensibility by stretching under conditions that simultaneously satisfy the following requirements without winding (1) Stretching ratio: 1.05 to 2.30 (2) Stretching temperature ≦ 110 ° C. (3) Heat setting temperature ≧ 110 ° C.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, various problems in relaxation heat treatment and constant-length (tensile) heat treatment can be solved by adopting a spinning direct drawing method under specific drawing conditions, and the productivity can be further improved. Things.

The polyester referred to in the present invention includes polyethylene terephthalate (hereinafter abbreviated as PET), polypropylene terephthalate (hereinafter abbreviated as PPT), polybutylene terephthalate (hereinafter abbreviated as PBT) and the like. PET is the most general. preferable. Further, a part of the diol component and a part of the acid component may be substituted with other copolymerizable components in a range of 15 mol% or less.
They may also contain additives such as other polymers, matting agents, flame retardants, antistatic agents, pigments and the like. Hereinafter, P
A method for producing a spontaneously elongated yarn will be described using ET as an example.

In the present invention, the temperature condition at the time of stretching is important. In the present invention, the drawing temperature is the preheating temperature of the yarn immediately before drawing,
That is, in the spinning direct drawing method, it indicates the first hot roller temperature. At this time, the stretching temperature must be 110 ° C. or less. If the drawing temperature is higher than 110 ° C., the crystallization of the PET fiber proceeds excessively before drawing, so that spontaneous elongation cannot be imparted to the drawn yarn no matter how the heat setting temperature is adjusted. Stretching temperature is glass transition temperature ~
A temperature of 95 ° C. is preferable because stretching is uniform. The temperature is more preferably 85 to 95 ° C. The glass transition temperature is PET
Using a PerkinElmer DSC 7 chip, a sample amount of 10 mg,
It was measured at a heating rate of 16 ° C./min.

In the present invention, the heat setting temperature is the heat treatment temperature of the drawn yarn, that is, the second temperature in the direct spinning method.
It refers to hot roller temperature. At this time, the heat setting temperature must be 110 ° C. or higher. When the heat setting temperature is lower than 110 ° C., the crystallization of the drawn yarn does not proceed, so that the fixation of the oriented amorphous molecular chains becomes insufficient, and spontaneous elongation is imparted to the drawn yarn no matter how the drawing temperature is adjusted. Can not be done. If the heat setting temperature is 180 ° C. or lower, the yarn sway during heat setting is small, which is preferable. More preferably 150 ° C, more preferably 140 ° C, most preferably
135 ° C or less.

JP-A-64-6115 discloses a method in which POY is heat-treated under a heating condition of dry heat of 140 to 220 ° C. while giving an elongation of 1 to 12%. However, this method heat-treats the undrawn yarn once wound, and is clearly different from the present invention which is a direct drawing method of spinning. Also, the stretching temperature is 140 ° C. or higher, which is clearly different from the present invention. Further, according to FIG.
The resulting fiber also has a constant stress elongation region that virtually disappears and has a load elongation curve close to that of a normal drawn yarn, and also has a density of 1.
It becomes 365 g / cm ³ or more and is distinguished.

In the present invention, the draw ratio is important together with the temperature conditions at the time of drawing, and it is necessary to set the draw ratio in accordance with the degree of orientation of the undrawn yarn immediately before entering the first hot roller. The stretching ratio in the present invention is defined by the peripheral speed ratio of the first hot roller and the second hot roller, that is, [second hot roller peripheral speed / first hot roller peripheral speed].

When the birefringence of the undrawn yarn is 0.020 to 0.065, the draw ratio is 1.01 to 1.35. If the magnification is lower than this, the yarn sway will increase and the process stability will decrease. If the ratio is higher than this, spontaneous elongation cannot be imparted because the oriented crystallization of the drawn yarn proceeds too much. Preferably 1.01-1.
If it is 25 times, a spontaneously elongated yarn can be obtained stably.
The birefringence of the undrawn yarn is the hot roller temperature at room temperature,
It was determined by measuring the birefringence of the wound fiber with a draw ratio of 1.00.

When the undrawn yarn is a fiber having a lower degree of orientation, it is necessary to increase the draw ratio accordingly. In the case of a low-orientation undrawn yarn having a birefringence of less than 0.020, the drawing ratio needs to be in the range of 1.05 to 2.30.
If the stretching ratio exceeds 2.30 times, the orientation crystallization proceeds excessively, so that spontaneous elongation cannot be imparted no matter how other conditions are changed. On the other hand, the draw ratio is 1.05
If the magnification is lower than twice, the oriented crystallization of the fiber hardly proceeds, so that spontaneous elongation cannot be imparted. Thus, the draw ratio depends on the degree of orientation of the undrawn yarn, for example, for a fiber having a birefringence of 0.015, a draw ratio of 1.25
~ 1.60 times, draw ratio of 1.80 for fiber with birefringence 0.007
When it is up to 2.20 times, spontaneous elongation can be imparted.
The stretching may be one-stage stretching or multi-stage stretching using three or more hot rollers.

When the birefringence of the undrawn yarn is 0.025 to 0.050, the process is further stabilized and the yarn spots are preferably reduced. More preferably, the birefringence of the undrawn yarn is from 0.030 to 0.045.

In some cases, for example, as disclosed in Japanese Patent Application Laid-Open No. 57-112428, the production of thick and thin yarns is carried out by stretching at a low draw ratio of POY. It is about twice as high as the draw ratio of the present invention. In addition, the publication and JP-A-57-143515
As described in Japanese Patent Application Publication No. H10-157, simply stretching to obtain a thick and thin yarn results in an extremely high fiber shrinkage,
Relaxation heat treatment is essential to reduce shrinkage. Therefore, it is clearly different from the present invention in which the relaxation heat treatment is not performed.

In the present invention, the spontaneous elongation rate and the boiling water shrinkage rate are defined by the following equations.

Spontaneous elongation rate (%) = [(L ₂ −L ₀ ) / L ₀ )] × 100 (1) Boiling water shrinkage rate (%) = [(L ₀ −L ₁ ) / L ₀ )] × 100 (2) L ₀ : The original length of the shackle measured under an initial load of 0.09 cN / dtex after shackling the drawn yarn. L ₁ : The shackle measuring L ₀ is substantially free of load in boiling water for 15 minutes. treated, air-dried initial load 0.09cN / dtex skein length under L _2: L ₁ for 15 minutes with the load-free further dry heat 160 ° C. the skein was measured, air-dried initial load 0.09cN / dtex Shackle length below The spontaneous elongation in the present invention means that the spontaneous elongation rate is 0%
It means that the above values are shown. If the spontaneous elongation is 0 to 5%, a soft and swelled polyester woven / knitted fabric can be obtained. Preferably, the spontaneous elongation is at least 1.5%.

If the boiling water shrinkage is 1% or less, spontaneous elongation in a dry heat set from scouring of the fabric can be suppressed to a low level, so that a good quality fabric can be obtained. 1% boiling water shrinkage
If the temperature exceeds the limit, spontaneous elongation in the dry heat setting from scouring becomes too large, and the loop of spontaneously elongated yarn floating on the surface of the fabric is disturbed, resulting in deterioration of the quality of the fabric. Preferably, the boiling water shrinkage is 0% or less.

As the spinning direct stretching apparatus, a known apparatus having two Nelson-type hot rollers can be used. A cold draw roller, a hot roller for multi-stage stretching, a non-contact dry heat or a steam heater for strengthening heat setting, etc. may be attached to this.

In the spontaneously elongated yarn obtained in the present invention, the cross-sectional shape of the fiber is not particularly limited, and a round cross-section, a triangular or other irregular cross-section, a hollow cross-section, or the like can be employed. The single-fiber fineness is also not particularly limited, but is preferably 0.3 to 5.0 dtex in consideration of use for the sheath yarn of the differential shrinkage mixed fiber. More preferably, it is 0.6 to 3.0 dtex.

In the present invention, spontaneous elongation is imparted by controlling the oriented crystallization of the drawn yarn by the drawing conditions. Therefore, the density of the drawn yarn is preferably 1.360 g / cm ³ or less. If the density is higher than this, the crystallization of the drawn yarn proceeds excessively, which is disadvantageous for the expression of spontaneous elongation. More preferably, the density is 1.358 g / cm ³ or less. Further, even if the degree of crystallization is too low, the fixation of the oriented amorphous molecular chains which governs the contraction of the fiber becomes insufficient, so that the density is preferably 1.348 g / cm ³ or more. In addition, the birefringence of the drawn yarn is substantially higher than that of the undrawn yarn since the drawing is substantially performed.

In the present invention, spontaneous elongation is imparted by drawing an undrawn yarn under specific conditions. However, as described in Japanese Patent Application Laid-Open No. 9-21028, it has been conventionally considered that spontaneous elongation cannot be imparted when an undrawn yarn is substantially drawn. However, in the present invention, spontaneous elongation can be imparted by specifying stretching conditions and controlling oriented crystallization. The spontaneous elongation mechanism of the drawn yarn is not well understood,
It is considered that the rearrangement of the PET molecular chains is related to the heat treatment in the intermediate set or the like. Therefore, it is necessary to keep the drawn yarn as a precursor in an appropriately oriented and crystallized state.

In the present invention, the spontaneously stretched yarn obtained by drawing the undrawn yarn at a low magnification is entangled and mixed with a polyester shrink yarn having a boiling water shrinkage of 10% or more, and used as a shrinkage difference mixed yarn. Is preferred. If the boiling water shrinkage of the polyester shrink yarn is 15% or more, it is preferable because the swelling feeling is further excellent. When the spontaneous elongation after shrinkage of the polyester shrinkable yarn is 0 to 5%, the texture becomes softer and more resilient, which is preferable. However, the spontaneous elongation rate after contraction is defined as [(L ₂ −L ₁ ) / L ₁ ] × 100. When the same heat treatment as in the measurement of the spontaneous elongation rate is performed on the shrink yarn, the length of the shackle measured after shrinking in boiling water is L ₁ , and the length of the shackle after further shrinking by dry heat is L ₂ . .

When a fiber having excellent stretchability such as PPT or PBT is used as the polyester shrink yarn,
ET is also different from ET and has a soft and resilient texture, which is preferable.

Very recently, Japanese Patent Application Laid-Open No. 9-273043 discloses a method for producing a spontaneously elongated yarn in which POY is subjected to a contact heat treatment at a glass transition temperature of 130 ° C. under a stress of 0.02 to 0.12 g / d. However, the spontaneous elongation described in the publication is defined as dry heat shrinkage-boil water shrinkage ≤0%, which is different from the spontaneous elongation described in the present invention. That is, in this publication, the original length before the heat treatment is not used as a reference, and in most cases, the contraction actually occurs after the heat treatment. In the examples of the publication, the boiling water shrinkage rates are all 2% or more, and when considered in the spontaneous elongation rate in the present invention, most are -2% or less. Therefore, the fiber obtained by the method is different from the fiber obtained by the present invention. Furthermore, the processing speed is extremely slow at 100 m / min due to the processing using a hot plate, and the production efficiency is very poor. In addition, thread breakage and spots frequently occur, which is inferior to the present invention.

As described above, the present invention is a method which is very excellent in cost reduction, process stabilization, and the like, but the resulting spontaneously elongated yarn has less spots than the one produced by the conventional two-step method and has less stain spots. It is also an advantage that the quality has been greatly improved.

The fiber obtained according to the present invention is suitably used for clothing such as blouses, suits, pants, coats and the like.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. In addition, the measuring method in the Example used the following method.

A. Intrinsic viscosity [η] Measured in orthochlorophenol at 25 ° C.

B. Spontaneous elongation rate and boiling water shrinkage rate Spontaneous elongation rate (%) = [(L ₂ −L ₀ ) / L ₀ )] × 100 Boiling water shrinkage rate (%) = [(L ₀ −L ₁ ) / L ₀ ) ] × 100 L _0: original length L of the skein was measured at a draw yarn skein up to under initial load of 0.09cN / dtex _1: treated for 15 minutes in boiling water skein was measured L ₀ in a substantially it loads free state After air drying, the shackle length under the initial load of 0.09 cN / dtex L ₂ : The shackle whose L ₁ was measured was further treated at 160 ° C. in dry heat with no load, for 15 minutes, and then under the initial load of 0.09 cN / dtex after air drying. Shackle length at C. Strength and elongation Initial sample length = 50 mm, tensile speed = 50 mm / min, JIS L
The load-elongation curve was determined according to 1013. Next, the load value was divided by the initial fineness, which was taken as the strength, and the elongation was divided by the initial sample length to obtain the elongation.

D. Constant stress extension area In the load-elongation curve obtained by the above method, the area showing a constant load value after the yield point is defined as the constant stress extension area, and the constant load value is divided by the initial fineness to determine the constant stress extension area stress, constant stress The elongation at the end point of the elongation region was divided by 100% to obtain a constant stress elongation region length.

E. Birefringence OLIMPUS BH-2 The retardation and optical path length of a single yarn were measured with a polarizing microscope, and Δn was determined.

F. Density As described in ASTM D1505-63T, the measurement was performed at 25 ° C. using a density gradient tube using an aqueous sodium bromide solution. Then, the density was corrected by setting the titanium oxide density to 3.84 g / cm ³ , and PE
The density of only the T portion was determined.

Example 1 Homo PET having an intrinsic viscosity of 0.63 (containing 0.4% by weight of titanium oxide)
Was melted at 285 ° C., filtered using a stainless steel nonwoven fabric filter 2 having an absolute filtration diameter of 15 μm, and then discharged at a spinning temperature of 285 ° C. from a round hole die 3 having a hole diameter of 0.25 mm, a hole length of 0.4 mm and 24 holes. . With the peripheral speed of the first hot roller 8 being 3000 m / min, the yarn was taken out, and the peripheral speed and discharge amount of the second hot roller 9 were appropriately changed to wind up a multifilament of 56 dtex and 24 filaments (FIG. 2). At this time, the temperature of the first hot roller 8 was 90 ° C., the temperature of the second hot roller 9 was 133 ° C., and the heat treatment time in the second hot roller 9 was 0.15 seconds. The undrawn yarn birefringence before entering the first hot roller 8 was 0.039, the density was 1.339 g / cm ³ , and the constant stress elongation region length was 0.58 (FIG. 3) (Experiments Nos. 1 to 4). ). FIG. 1 shows the change in the spontaneous elongation ratio with respect to the stretching ratio. Also,
Table 1 shows the physical property values. When the draw ratio is 1.25 or less, it is understood that the drawn yarn exhibits spontaneous elongation. Experiment N
o. 3 is shown in FIG. 3 at the same time as the unstretched yarn. Although the yield point exists, the constant stress elongation region is significantly reduced as compared with the unstretched yarn, and the stress value in the constant stress elongation region is shown. And the dimensional stability during weaving was satisfactory. In addition, there was no yarn sway or yarn breakage during stretching, and the yarn could be produced without any problem. In addition, it was of high quality with almost no staining spots.

Comparative Example 1 Direct spinning was performed under the same conditions as in Example 1 except that the draw ratio was 1.37 (Experiment No. 5). Table 1 shows the physical properties.
Shown in Since the draw ratio was too high, the drawn yarn shrunk conversely, and it was impossible to impart spontaneous elongation.

[0041]

[Table 1] Example 2 The temperature of the second hot roller 9 was 130 ° C., and the stretching ratio was 1.10.
Direct spinning was performed under the same conditions as in Example 1 except that the temperature of the first hot roller 8 was changed as shown in Table 2 (Experiments Nos. 6 to 11). Table 2 shows the physical property values. If the temperature of the first hot roller 8 is 110 ° C. or lower, it is understood that the drawn yarn exhibits spontaneous elongation. Also, yarn swaying during stretching,
Yarn could be produced without any problems such as thread breakage. In addition, it was of high quality with almost no staining spots.

However, if the temperature of the first hot roller 8 is 30
In the case of ° C., although not so much as to cause a problem, slight staining spots occurred. Further, when the temperature of the first hot roller 8 became 100 ° C. or more, the yarn was slightly shaken, and the spontaneous elongation rate was low.

Comparative Example 2 Direct spinning was performed under the same conditions as in Example 2 except that the temperature of the first hot roller 8 was set to 120 ° C. (Experiment No. 2).
12). Since the temperature of the first hot roller 8 is too high, the oriented crystallization proceeds excessively and the drawn yarn shrinks in reverse,
Spontaneous elongation could not be imparted.

[0044]

[Table 2] Example 3 The draw ratio was 1.10 times and the temperature of the second hot roller 9 was as shown in Table 3.
The stretching was performed under the same conditions as in Example 1 except for the changes as described above (Experiments Nos. 13 to 16). Table 3 shows the physical property values.
When the temperature of the second hot roller 9 was 110 ° C. or higher, the drawn yarn exhibited spontaneous elongation. In addition, there was no yarn sway or yarn breakage during stretching, and the yarn could be produced without any problem. In addition, it was of high quality with almost no staining spots.

Comparative Example 3 Stretching was performed under the same conditions as in Example 3 except that the temperature of the second hot roller 9 was set to 100 ° C. (Experiment No. 17).
Table 3 shows the physical property values. Since the heat setting temperature was too low, the drawn yarn shrunk conversely, and it was impossible to impart spontaneous elongation.

[0046]

[Table 3] Example 4 The peripheral speed of the first hot roller 8 was 2200 m / min, and the stretching ratio was 1.32.
Direct spinning was performed under the same conditions as in Example 1 except that the number was doubled, and a fiber of 56 dtex and 24 filaments was wound up (Experiment No. 18). The birefringence of the undrawn yarn before entering the first hot roller 8 was 0.021. Table 4 shows physical properties
Shown in At this time, it is also understood that the drawn yarn exhibits spontaneous elongation. In addition, there was no yarn sway or yarn breakage during stretching, and the yarn could be produced without any problem. In addition, it was of high quality with almost no staining spots.

Example 5 The peripheral speed of the first hot roller 8 was 2000 m / min, and the stretching ratio was 1.08.
Direct spinning was performed under the same conditions as in Example 1 except that the number was doubled, and a fiber of 56 dtex and 24 filaments was wound up (Experiment No. 19). The undrawn yarn birefringence before entering the first hot roller 8 was 0.019. Table 4 shows physical properties
Shown in At this time, it is also understood that the drawn yarn exhibits spontaneous elongation. In addition, there was no yarn sway or yarn breakage during stretching, and the yarn could be produced without any problem. In addition, it was of high quality with almost no staining spots.

Comparative Example 4 Stretching was performed under the same conditions as in Example 5 except that the stretching ratio was changed to 1.02 (Experiment No. 20). Table 4 shows the physical property values. Since the draw ratio was too low, the orientation crystallization was insufficient and the drawn yarn shrunk conversely, failing to impart spontaneous elongation.

Example 6 The peripheral speed of the first hot roller 8 was 1700 m / min, and the stretching ratio was 1.45.
Direct spinning was performed under the same conditions as in Example 1 except that the number was doubled, and a fiber of 56 dtex and 24 filaments was wound up (Experiment No. 21). The birefringence of the undrawn yarn before entering the first hot roller 8 was 0.015. Table 4 shows physical properties
Shown in At this time, it is also understood that the drawn yarn exhibits spontaneous elongation. In addition, there was no yarn sway or yarn breakage during stretching, and the yarn could be produced without any problem. In addition, it was of high quality with almost no staining spots.

[0050]

[Table 4] Example 7 The peripheral speed of the first hot roller 8 was 1000 m / min, and the stretching ratio was 2.01.
Direct spinning was performed under the same conditions as in Example 1 except that the number was doubled, and a fiber of 56 dtex and 24 filaments was wound up (Experiment No. 22). The birefringence of the undrawn yarn before entering the first hot roller 8 was 0.007. Table 4 shows physical properties
Shown in At this time, it is also understood that the drawn yarn exhibits spontaneous elongation. In addition, there was no yarn sway or yarn breakage during stretching, and the yarn could be produced without any problem. In addition, it was of high quality with almost no staining spots. However, although not so much as to cause a problem, staining spots slightly occurred as compared with Examples 1 to 3.

Example 8 Spinning was performed under the same conditions as in Example 1 except that the discharge amount was changed and a known POY winding device was used, and an undrawn yarn having 61 dtex, 24 filaments and a birefringence of 0.038 was wound. Was. Then, it is stretched by a known stretching machine at a preheating temperature of 85 ° C., a heat setting temperature of 90 ° C., a stretching ratio of 1.85 times, and a stretching speed of 800 m / min, 33 dtex, 24 filament, boiling water shrinkage of 21.2%,
A contracted yarn having a spontaneous elongation rate of 1.8% after contraction was obtained. Experiment N
o. The fibers were mixed with the spontaneously elongated yarn of No. 3 (spontaneous elongation ratio of 2.4%) in an interlaced manner to obtain a 84dtex, 48 filament shrinkage differential mixed yarn. This was S-twisted at 300 turns / m, and the Venetian was woven with a zokki. This was subjected to a 10% alkali weight reduction by a conventional method, followed by dyeing and dry heat setting. In the obtained fabric, the spontaneously elongated yarn emerged on the surface of the fabric, was soft, had a swelling feeling, and was excellent in resilience.

Comparative Example 5 Spinning was carried out under the same conditions as in Example 8 except that the discharge amount was changed. 56 dtex, 24 filaments, birefringence 0.040, density
1.339 g / cm ³ of an undrawn yarn was obtained. Using the apparatus shown in FIG. 4, the temperature of the hot roller 13 is 80 ° C., the stretching speed is 450 m / min, the stretching ratio is 1.84 times, and the temperature of the non-contact heater 15 (effective length 500 m
m) Processing was performed by performing a relaxation heat treatment at 220 ° C. between the first cold roller 14 and the second cold roller 16 at a relaxation rate of 35%. However, the stretching speed is the first cold roller 14
The peripheral speed and the relaxation (%) are [(the peripheral speed of the first cold roller 14-the peripheral speed of the second cold roller 16) / the first
Peripheral speed of cold roller 14] × 100. The spontaneous elongation of the obtained fiber was 3.8%.
However, thread breakage frequently occurred during processing, and the restart success rate after the doff was low. Further, the substantial processing speed was 293 m / min, which was much lower in productivity than the present invention. In addition, staining spots were large and of low quality.

[0053]

By adopting the method for producing a polyester fiber of the present invention, a spontaneously elongated yarn having excellent quality can be easily obtained with good operability and productivity, and a woven or knitted fabric having excellent texture and high quality can be obtained. It can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change in a spontaneous elongation ratio with respect to a stretching ratio.

FIG. 2 is a diagram illustrating a direct spinning apparatus for spinning.

FIG. 3 is a diagram illustrating a strength-elongation curve.

FIG. 4 is a diagram showing a processing apparatus.

[Explanation of symbols]

1: spin block 11: undrawn yarn 2: non-woven fabric filter 12: feed roller 3: base 13: hot roller 4: chimney 14: first cold roller 5: thread 15: non-contact heater 6: lubrication guide 16: second Cold roller 7: Interlace nozzle 17: Processed yarn 8: First hot roller 9: Second hot roller 10: Winding yarn

Claims (6)

[Claims] A polyester is melt-spun to obtain a birefringence of 0.02.
A method for producing a polyester fiber, which is characterized in that a spun stretch is imparted by stretching under a condition that simultaneously satisfies the following requirements without being wound up, which is a yarn of 0 to 0.065. (1) Stretching ratio 1.01 to 1.35 (2) Stretching temperature ≦ 110 ° C. (3) Heat setting temperature ≧ 110 ° C. 2. Polyester is melt-spun to obtain a birefringence of 0.02.
A method for producing a polyester fiber, which comprises imparting spontaneous extensibility by drawing under conditions that simultaneously satisfy the following requirements without being wound up, and that the yarn is not wound. (1) Stretching ratio 1.05 to 2.30 (2) Stretching temperature ≤ 110 ° C (3) Heat setting temperature ≧ 110 ° C 3. The method for producing a polyester fiber according to claim 1, wherein the spontaneous elongation rate of the following formula (1) is 0 to 5% and the boiling water shrinkage rate of the formula (2) is 1% or less. Spontaneous elongation rate (%) = [(L ₂ −L ₀ ) / L ₀ )] × 100 (1) Boiling water shrinkage rate (%) = [(L ₀ −L ₁ ) / L ₀ )] × 100 (2) L ₀ : The original length of the shackle measured under an initial load of 0.09 cN / dtex by shackling the drawn yarn. L ₁ : The shackle measuring L ₀ is treated in boiling water for 15 minutes in a substantially load-free state. Shackle length under initial load of 0.09 cN / dtex after air drying L ₂ : The shackles whose L ₁ was measured were further treated at 160 ° C. in dry heat with no load applied for 15 minutes, and then air-dried under an initial load of 0.09 cN / dtex. Shackle length 4. The method for producing a polyester fiber according to claim 1, wherein the drawing is performed such that the density of the drawn yarn is 1.360 g / cm ³ or less. 5. A polyester fiber having spontaneous elongation obtained by the method according to claim 1 and a polyester fiber having a boiling water shrinkage of 10% or more are entangled and mixed. Of producing polyester fibers. 6. A polyester woven or knitted fabric characterized by using a polyester fiber obtained by the method according to any one of claims 1 to 5.