JPH1025620A - High-shrinkage polyester staple fiber and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high-shrinkage polyester staple fibers which give bulky woven fabric of high light fastness, swelling feel and soft touch by treating drawn yarns of a specific copolyester with heat under specific conditions. SOLUTION: Copolyester drawn fibers which contain isophthalic acid and 2,2-bis 4-(2-hydroxyethoxy)phenyl}propane as copolymerization components, simultaneously satisfy formulas I-III [p(a) is the molar fraction of isophthalic acid based on the whole acids in %; p(b) is the molar fraction of 2,2-bis 4-(2- hydroxyethoxy)phenyl}propane], have an intrinsic viscosity of >=0.52, a crystallinity of 15-30%, an optical birefrigence of 100×10<-3> -145×10<-3> and a shrinkage stress of >=150mg/d, are heat treated at 120-180 deg.C under -2-+5% relaxation for >=2 seconds whereby high-shrinkage polyester staple fibers are obtained with a boiling water shrinkage of <=20%, a dry heat shrinkage of 12-40% at 160 deg.C after treatment with boiling water, a dry heat shrinkage of 15-45% at 180 deg.C after treatment with boiling water, a change rate of <=15% with the lapse of time and a deformation rate >=1.2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-shrink polyester staple fiber, which has high light fastness and exhibits a large shrinkage against a restraint of a spun fabric in a high temperature region, thereby giving a feeling of swelling and softness. The present invention relates to a high-shrinkage polyester short fiber capable of obtaining a spun woven fabric having the following properties.

[0002]

2. Description of the Related Art High shrinkage fibers are used to produce bulky yarns and bulky woven or knitted fabrics by blending or blending with low shrinkage fibers and then heat-treating them at the yarn or fabric stage. . Conventional high-shrink polyester short fibers are generally obtained by drawing a low-molecular-weight polyester at a relatively low temperature and at a low magnification, and most of the shrinkage occurs during boiling water treatment or dyeing. If the shrinkage is insufficient, or even if the shrinkage is sufficiently high, it is affected by the process tension in the higher processing stage after dyeing, and if the previously shrunk fiber does not have sufficient bulkiness to elongate, There was a drawback to say.

In order to improve such disadvantages, Japanese Patent Publication No. Sho 5
JP-A-8-28373, JP-B-58-28374 and JP-B-58-30412 propose to improve the shrinkage characteristics by copolymerizing specific components. However, in all of these publications, the shrinkage in the fabric was insufficient because the dry heat shrinkage after the boiling water treatment was small. Also, Japanese Patent Application Laid-Open No. 55-57013 discloses 2
It has been proposed to improve the shrinkage characteristics by using a polyester obtained by copolymerizing 2bis {4- (2-hydroxyethoxy) phenyl} propane in an amount of 5 to 15 mol%. However, the inventors of the present application have found that light fastness is poor and dry heat shrinkage after boiling water treatment is small.
Further, there is a disadvantage that the fabric cannot exhibit sufficient shrinkage due to insufficient shrinkage stress. Japanese Patent Publication No. 61-13909 proposes that a polyester mixed fiber comprising a low shrinkage component and a high shrinkage component has a difference in boiling water shrinkage to impart bulkiness. However, dry heat treatment after boiling water treatment (scouring) (intermediate set, etc.)
There was a defect that sufficient shrinkage was not obtained at times. Furthermore, JP-A-2-19528 proposes to improve the light fastness and shrinkage characteristics by using a polyester containing a specific component in a specific ratio, and the dry heat shrinkage characteristics after boiling water treatment have been considerably improved. However, there was a drawback that the shrinkage rate changed over time. Japanese Patent Application Laid-Open No. Hei 3-249239 proposes that a polyester mixed yarn comprising a low shrinkage component and a high shrinkage component having a difference in boiling water shrinkage of 20% or more improves the shrinkage characteristics and imparts a soft feeling. ing. However, when the spun yarn is formed into a spun yarn due to an excessively high boiling water shrinkage ratio, there is a drawback in that the twisting set and the warp are greatly shrunk when glued and dried.

[0004]

As needs are diversifying, demands for bulky woven or knitted fabrics are still strong. Many proposals have been made to improve the bulkiness, and improvements have been made. However, as described above, sufficient shrinkage does not appear under the binding force of the fabric, and the level has not reached the level satisfying the requirements. Further, when a special component is copolymerized in order to increase shrinkage, there is a disadvantage that light fastness is deteriorated.

An object of the present invention is to provide a bulky woven fabric having a good light fastness and a sufficient swelling and softness even with a fabric having a large binding force such as a spun woven fabric. An object of the present invention is to provide polyester short fibers.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hot water shrinkage of not more than 20%, a dry heat shrinkage of 160 ° C. after boiling water treatment of 12 to 40%, and a heat shrinkage of 180 ° C. after boiling water treatment. Fifteen
To 45%, and the rate of change with time is 15% or less.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The high-shrinkable polyester short fibers of the present invention require that the shrinkage characteristics of raw cotton be within a specific range, and that the boiling water shrinkage be 20% or less. If the boiling water shrinkage exceeds 20%, shrinkage will occur during twist setting of the spun yarn and drying of the warp with sizing, resulting in poor process stability. In addition, the boiling water shrinkage rate is 20
%, The dry heat shrinkage after the boiling water treatment cannot be increased. The boiling water shrinkage is preferably 17% or less,
More preferably, it is 15% or less. Although the lower limit of the boiling water shrinkage is not particularly limited, it is preferably 5% or more in order to improve the process passability.

In the actual process, the dry heat shrinkage after the boiling water treatment is a very important factor. That is, the large shrinkage at the time of bulk-up due to dry heat after dyeing gives the swelling to the woven fabric, and can make the woven fabric soft. In that sense, 160 after boiling water treatment
The dry heat shrinkage at 12 ° C. is 12 to 40%,
The dry heat shrinkage at 80 ° C. needs to be 15 to 45%. If the dry heat shrinkage after the above-mentioned boiling water treatment is lower than the above range, sufficient bulkiness cannot be obtained when blended with low shrinkage short fibers, and the object of the present invention cannot be achieved.

Conversely, if the dry heat shrinkage is higher than the above range, the shrinkage becomes too large, the shrinked fibers become thicker, and the whole fabric becomes coarse and hard, thereby achieving the object of the present invention. Can not. The dry heat shrinkage at 160 ° C. after the boiling water treatment is preferably 16 to 30%, and the dry heat shrinkage at 180 ° C. after the boiling water treatment is preferably 18 to 30%.
35%.

In the present invention, the rate of change with time, which will be described later, must be 15% or less. Typically,
The larger the shrinkage ratio, the smaller the binding force, and the higher the standing temperature, the greater the change over time in the shrinkage ratio, and the shrinkage ratio changes over time. If the change with time is large as described above, it is difficult to obtain a constant shrinkage ratio, and the bulkiness is not uniform. Therefore, the smaller the change over time is, the better. However, as a result of intensive studies by the present inventors, it has been found that by setting the rate of change over time to 15% or less, the swelling feeling of the obtained woven fabric can be maintained for a long period of time. The rate of change over time (%)
Is a value obtained by the following equation. {(Initial boiling water shrinkage rate-boiling water shrinkage rate after aging) / initial boiling water shrinkage rate} x 100 Here, the boiling water shrinkage rate after aging is 40 in an unrestrained state.
It refers to the boiling water shrinkage when left in an atmosphere at 10 ° C. for 10 days.

In order to reduce the rate of change over time, it is preferable that the internal structure of the fiber is dense while maintaining high shrinkage, and the degree of crystallinity by the density method showing the denseness of the internal structure is 15% or more. Preferably, there is. If it is less than 15%, the rate of change with time is large, and it may be difficult to impart uniform bulkiness to the woven fabric. A more preferable crystallinity is 18% or more. On the other hand, if the crystallinity is too high, the shrinkage decreases, so the crystallinity is preferably 30% or less.

Further, the birefringence according to the compensator method, which indicates the degree of molecular orientation as a factor determining the internal structure, is 1
It is preferable to be in the range of 10 × 10 ^{−3 to} 145 × 10 ⁻³ from the viewpoint of shrinkage characteristics and the rate of change with time. Birefringence is 110 ×
When it is lower than 10 ^{-3, the} degree of orientation of the amorphous portion can be maintained, but the degree of crystallization tends to be low, so that the change with time tends to be large. On the other hand, when it is higher than 145 × 10 ⁻³ , the degree of shrinkage tends to be too low because the crystallinity is high.

Further, the polyester for high shrinkage polyester short fibers of the present invention comprises isophthalic acid and 2.2 bis {4- (2-hydroxyethoxy) phenyl} propane as copolymerization components, and has the following formulas I, II and III: Is preferable. P (a) + 1.5 × P (b) ≧ 8.5 −−− IP (a) + P (b) ≦ 18.0 −−−− II 1.0 ≦ P (b) ≦ 5.5 --- III (wherein, P (a) is the mole fraction (%) of isophthalic acid with respect to all the acid components in the copolymerized polyester, and P (b) is the mole fraction of all the glycol components in the copolymerized polyester. 2.
It is the mole fraction (%) of 2-bis {4- (2-hydroxyethoxy) phenyl} propane. )

The copolyester for high-shrink polyester short fiber is isophthalic acid or 2.2 bis @ 4-
Copolymerized polyesters containing only one of (2-hydroxyethoxy) phenyl @ propane as a copolymer component tend not to exhibit the shrinkage characteristics of the present invention, and have a light fastness, a feeling of swelling and a soft feeling. Not only in terms of dyeability, but also in terms of dyeing properties, it tends to be unlikely to be a high-shrinkable polyester short fiber suitable as a high-quality woven or knitted fabric.
Also, the combination of one of isophthalic acid or 2.2 bis {4- (2-hydroxyethoxy) phenyl} propane with another copolymer component simultaneously satisfies the shrinkage characteristics and light fastness specified in the present invention. It tends to be difficult.

[0015] The copolymerized polyester for a high-shrinkable polyester short fiber of the present invention comprises isophthalic acid and 2.2 bis @ 4-
It is preferable that the copolymerized polyester satisfying the formula (I) using (2-hydroxyethoxy) phenyl} propane as a copolymerization component. P (a) + 1.5 × P (b) ≧ 8.5 ----- Here, P (a) is isophthalic acid, and P (b) is 2.2 bis ｛4- (2-hydroxyethoxy). Phenyl｝ propane.

If P (a) + 1.5 × P (b) is less than 8.5, both the boiling water shrinkage and the dry heat shrinkage after the boiling water treatment tend to be low. In order to increase the shrinkage sufficiently, P
(a) + 1.5 × P (b) is preferably 12.0 or more.

Further, it is preferable to satisfy the formula II, P (a) + P (b) ≦ 18.0. P (a) + P (b) is 18.0
If the temperature exceeds the melting point, the melting point of the copolyester decreases to around 210 ° C., and the heat resistance also lowers, so that the yarn forming properties such as thread breakage during spinning and agglutination during stretching may deteriorate. In addition, it is preferable that P (a) + P (b) is 16.0 or less, because more stable spinning and drawing can be performed.

It is preferable that the formula III satisfies 1.0 ≦ P (b) ≦ 5.5. When P (b) is less than 1.0, the above-mentioned shrinkage characteristics, especially the dry heat shrinkage after the boiling water treatment, may not be satisfied even when the spinning and drawing conditions are changed. On the other hand,
Copolyester staple fibers containing 2-bis {4- (2-hydroxyethoxy) phenyl} propane tend to have a remarkable decrease in light fastness as the copolymerization fraction of the copolymerization component increases, and P ( b) It is preferred that ≦ 5.5. Regarding the light fastness, more preferable results are obtained when P (b) is 4.6 or less.

In the present invention, isophthalic acid and 2
・ 2bis {4- (2-hydroxyethoxy) phenyl}
By co-polymerizing with propane, more preferably, isophthalic acid is copolymerized at a higher rate than 2.2 bis {4- (2-hydroxyethoxy) phenyl} propane, thereby suppressing a decrease in light fastness. There is a tendency.

Here, the copolymerized polyester means that isophthalic acid and 2.2 bis {4-
A compound having a structure in which (2-hydroxyethoxy) phenyl @ propane is randomly copolymerized is shown. Polyethylene terephthalate is preferred as the base polyester. The copolymerized polyester may contain diethylene glycol or the like in the main chain as long as it is produced as a by-product in the production process, or isophthalic acid and 2 × as long as the highly shrinkable polyester short fiber of the present invention can be produced. 2-bis 4-
A copolymer component other than (2-hydroxyethoxy) phenyl @ propane may be contained.

Additives such as titanium oxide may be added to the highly shrinkable polyester short fibers of the present invention as long as the object of the present invention is not impaired.

The high-shrinkable polyester staple fiber simply has a high shrinkage ratio in order to exhibit excellent swelling and softness in mixed-shrink or mixed-knit woven fabric of different shrinkage. Is not sufficient, and it is important that the contraction force, which overcomes the binding force of the knitted fabric, that is, the contraction stress is high. Therefore, the shrinkage stress of the high-shrinkable polyester short fiber of the present invention is preferably 150 mg / d or more, and more preferably 250 mg / d or more. Shrinkage stress is 150mg / d
If it is less than 30, the knitted woven fabric under the binding force tends to hardly exhibit sufficient shrinkage.

Further, the intrinsic viscosity of the high-shrinkable polyester short fiber of the present invention is preferably 0.52 or more.
Conventional high-shrinkable short fibers have a low intrinsic viscosity in order to impart anti-pill properties, and the dry heat shrinkage after boiling water treatment cannot be increased. However, at present, it has become possible to increase the intrinsic viscosity because effective anti-pill processing is possible after forming a woven fabric, and it is possible to adopt a condition in which the dry heat shrinkage after the boiling water treatment can be increased. If the intrinsic viscosity is less than 0.52, the shrinkage, especially the dry heat shrinkage and the shrinkage stress after the boiling water treatment, tend to hardly increase. In other words, in order to obtain a high dry heat shrinkage and a high shrinkage stress after the high boiling water treatment as defined in the present invention, it is extremely effective to stretch the undrawn yarn at a high temperature and a high magnification and then to perform a constant length heat treatment. However, when the intrinsic viscosity is low, all of high-temperature stretching, high-magnification stretching, and heat treatment after stretching may be difficult. Particularly preferred intrinsic viscosity is 0.60 or more. It is effective to increase the intrinsic viscosity in order to increase the shrinkage property. However, if the intrinsic viscosity is too high, it is difficult to prevent the occurrence of pills even if anti-pill processing is performed after the fabric is formed. .68 or less.

The cross-sectional shape of the high-shrinkable polyester short fiber of the present invention is not particularly limited, but a cross section of three or more leaves such as a T cross section or a Y cross section is preferable in the silky field. Further, the degree of deformation of the cross section is preferably 1.2 or more because high gloss can be imparted.

The fineness and length of the high-shrinkable polyester short fiber of the present invention are not limited, but the fineness is 0.5 to 5.0 d.
Can be preferably used. After heat-treating the woven fabric, the high-shrink staple fibers are located at the center of the spun yarn, and therefore are preferably at least 1.2 d for the purpose of imparting waist and tension. The fiber length is
It is preferably from 32 to 110 mm.

Next, a method for producing the high shrinkage polyester short fiber of the present invention will be described. In order to produce the high shrinkage polyester short fiber of the present invention, isophthalic acid and 2.2 bis {4- (2-hydroxyethoxy) phenyl} propane are used as copolymerization components and the following formulas I, II and III are simultaneously satisfied. And a copolyester stretched fiber having an intrinsic viscosity of 0.52 or more at a relaxation rate of -2 to 5%.
This is achieved by a method for producing a high-shrinkable polyester short fiber, which comprises heat-treating at 180 ° C for 2 seconds or more.

P (a) + 1.5 × P (b) ≧ 8.5 −−− IP (a) + P (b) ≦ 18.0 −−−− II 1.0 ≦ P (b) ≦ 5.5 (where P (a) is the molar fraction (%) of isophthalic acid with respect to all the acid components in the copolymerized polyester, and P (b) is the total fraction in the copolymerized polyester. 2 against glycol component
It is the mole fraction (%) of 2-bis {4- (2-hydroxyethoxy) phenyl} propane. In order to produce the high-shrinkable polyester short fiber of the present invention, the above-mentioned copolymerized polyester is melt-spun, taken up at a predetermined speed, plied, and once stored in a can.
The obtained subtows are stretched in a commonly used liquid bath while a plurality of subtows are aligned, and then heat-treated. In this manufacturing process, the stretched fiber is heated at a relaxation rate of -2 to 5% at a temperature of 12%.
After heat-treating at 0 to 180 ° C. for 2 seconds or more, the tow is inserted into the crimper, crimped, a predetermined treating agent is applied, and cut with a cutter to obtain the high-shrinkable polyester short fiber of the present invention. Becomes possible. If the relaxation rate in the heat treatment of the drawn fiber is less than -2%, the winding of the single yarn around the roll or the breakage of the yarn frequently occurs during the heat treatment, and the yarn-making property is greatly reduced. On the other hand, if the relaxation rate exceeds 5%, the yarn path will not be stable, and it will be difficult to apply a uniform heat treatment to the yarn, resulting in large uneven shrinkage.

On the other hand, if the heat treatment temperature is lower than 120 ° C., the shrinkage in the low temperature region cannot be sufficiently suppressed, which is not preferable. Conversely, if the heat treatment temperature exceeds 180 ° C., the shrinkage becomes too low, and sufficient shrinkage cannot be exhibited in a bulk-up process such as an intermediate set.

On the other hand, if the heat treatment time is less than 2 seconds, sufficient heat treatment cannot be performed, so that variations between single yarns occur, which causes uneven shrinkage. A preferred heat treatment time is 3 seconds or more.

The highly shrinkable polyester short fibers of the present invention are:
For example, it can be manufactured as follows. A chip of copolymerized polyethylene terephthalate containing 7.0% by mole of the acid component of the repeating unit and 4.0% by mole of the glycol component containing 2.2 bis {4- (2-hydroxyethoxy) phenyl} propane is obtained. . The obtained chip is spun at a spinning temperature of 290 ° C. and a spinning speed of 1300 m / min.
To obtain an undrawn yarn. 90% of the undrawn yarn
The stretching was performed under the conditions of a temperature of 150 ° C., a stretching ratio of 3.35 times, and a stretching speed of 150 m / min.
Heat treatment is performed at 0 ° C. for 4.5 seconds. Subsequently, by applying mechanical crimping to a fiber length of 76 mm, the highly shrinkable polyester short fiber of the present invention can be obtained.

[0031]

The present invention will be specifically described below with reference to examples. In addition, each physical property in an Example was calculated | required by the following method.

A. Boiling water shrinkage Original length (L0) with a load of 100mg per denier
Is measured and immersed in boiling water without load for 15 minutes. The length (L1) after the treatment with the load of 100 mg per denier after the boiling water treatment is measured. The boiling water shrinkage is determined by the following equation. Boiling water shrinkage = {(L0−L1) / L0} × 100 (%)

B. Dry heat shrinkage after boiling water treatment Immerse in boiling water without load for 15 minutes. Remove from boiling water and air dry at room temperature for at least 24 hours. The sample is applied with a load of 100 mg per denier, and the length (L2) after the boiling water treatment is measured. Put in the atmosphere of specified temperature without load, take out after 15 minutes, 100mg per denier
Under dry load, the length (L3) after the dry heat treatment is measured. The dry heat shrinkage after the boiling water treatment is determined by the following equation. Dry heat shrinkage after boiling water treatment = {(L2-L3) / L2} ×
100 (%)

C. Shrinkage stress Attach one end to strain gauge, 20 per denier
The other end is fixed by applying a tension of mg. The shrinkage stress generated during the treatment in an oven at 180 ° C. is recorded on a recorder, and the maximum value (mg / d) is determined.

D. Light fastness A sample for light fastness was used, using a fabric dyed with a disperse dye (RESOLINE BLUE FBL). Evaluation is JIS L0842 (Carbon arc lamp method)
8 steps based on Grade 8 is the best, and the lower the grade, the poorer the robustness. The target light fastness of the present invention was grade 4 or higher.

E. Swelling feeling, soft feeling Sensory evaluation was performed, and the results were judged in 9 steps. The case where the swelling feeling and the soft feeling were the worst was evaluated as the first grade.
The target swelling and soft feeling of the present invention are 5
Grade or higher was passed.

F. Intrinsic viscosity This is a value obtained by dissolving high-shrinkable polyester short fibers in O-chlorophenol and measuring at 25 ° C.

Example 1 After an esterification reaction was carried out using terephthalic acid / ethylene glycol and isophthalic acid / ethylene glycol slurry, a coloring inhibitor / ethylene glycol slurry was added, and then a polymerization reaction catalyst and titanium oxide / ethylene glycol After adding a slurry (0.1 wt% of titanium oxide to the obtained copolyester),
A solution of 2-bis {4- (2-hydroxyethoxy) phenyl} propane / ethylene glycol was added, and polymerization was carried out by a usual method to obtain a chip of a highly shrinkable copolymerized polyethylene terephthalate having the composition shown in Table 1.

After drying the obtained chips, the spinning temperature was 290.
At a spinning speed of 1300 m / min., An undrawn yarn having a degree of deformation of 1.4 and a Y-shaped cross section was spun at a spinning speed of 1300 m / min. This undrawn yarn is made into a 500,000-denier tow, drawn at a drawing temperature of 90 ° C., at a draw ratio of 3.35 times, at a drawing speed of 150 m / min. 4.5
After a heat treatment for 2 seconds to give a mechanical crimp, the fiber was cut into a 2.5d, 76 mm raw cotton. The intrinsic viscosity of the raw cotton was 0.62, and the physical properties of the fiber were as shown in Table 1. The yarn-making properties of this yarn-making were good without cutting the fiber. This raw cotton was blended with 1.5 d and 76 mm low-shrink raw cotton having a boiling water shrinkage of 0.5% at a ratio of 40% by weight and 60% by weight, respectively, to obtain a spun yarn of 30/2. The obtained spun yarn was used for warp and weft to obtain a green fabric having a weaving density of 61/45 (lines / inch).
The greige fabric was relaxed and scoured with hot water at 98 ° C, and finished at 170 ° C to prepare a woven fabric. The swelling feeling of the woven fabric was grade 8 and the feeling of softness was 8 and the sensory evaluation results were obtained. Further, as shown in Table 1, the light fastness was grade 7 and the woven fabric having the swelling feeling and soft feeling intended for the present invention was obtained. Obtained.

[0040]

[Table 1] Examples 2 to 5 and Comparative Examples 1 to 3 As shown in Table 1, except that the amounts of isophthalic acid as the acid component and 2.2 bis {4- (2-hydroxyethoxy) phenyl} propane as the glycol component were changed. In the same manner as in Example 1, various copolymerized polyethylene terephthalates were obtained, and a woven fabric was obtained in the same manner as in Example 1. Table 1 shows the results.
Shown in

Examples 2 to 5 are copolymerized polyethylene terephthalates within the scope of the present invention, and had good swelling feeling, soft feeling, and good light fastness.

On the other hand, Comparative Examples 1 and 3 are copolymerized polyethylene terephthalates in which only one of isophthalic acid and 2.2 bis {4- (2-hydroxyethoxy) phenyl} propane is copolymerized. Since the dry heat shrinkage at 160 ° C. after the treatment is less than 12% and the dry heat shrinkage at 180 ° C. after the boiling water treatment is less than 15%, the swelling and soft woven fabric aimed at by the present invention can be obtained. Did not.

Comparative Example 2 is a copolymerized polyethylene terephthalate in which the amounts of isophthalic acid and 2.2 bis {4- (2-hydroxyethoxy) phenyl} propane are outside the range of the formula II of the present invention. The polyester had a melting point lowered to 212 ° C., frequently broken yarns during spinning, had too high a shrinkage rate, and was a raw cotton that changed greatly with time, and was a woven fabric having poor softness.

Examples 6 to 9 and Comparative Examples 4 to 6 The same high shrinkage copolymerized polyethylene terephthalate as in Example 1 was used, and the temperature, time and relaxation rate of the heat treatment were changed as shown in Table 2, and A woven fabric was obtained in the same manner as in Example 1.
Table 2 shows the results.

Examples 6 and 7 were heat treatment conditions within the range of the present invention, and the results of the sensory evaluation of the swelling feeling and the soft feeling and the light fastness were good.

In Example 8, when the relaxation rate was changed to the lower limit of the present invention under the heat treatment conditions within the range of the present invention, the results of the sensory evaluation of the swelling feeling and the soft feeling and the light fastness were good. In addition, there was a tendency that single yarn winding was slightly caused and the yarn forming property was slightly inferior.

On the contrary, in Example 9, when the relaxation rate was changed to the upper limit of the present invention under the heat treatment conditions within the range of the present invention, the results of the sensory evaluation of the swelling feeling and the soft feeling and the light fastness were good. However, the stability of the yarn path tended to be slightly inferior.

On the other hand, in Comparative Example 4, since the heat treatment conditions were outside the range of the present invention, the fiber properties such as shrinkage properties were out of the range of the present invention, and the swelling feeling and the soft feeling, which were the objects of the present invention, were also obtained. No sensory evaluation result could be obtained.

In Comparative Example 5, the yarn was frequently broken at the time of stretching due to too low a relaxation rate of the heat treatment, resulting in poor stretchability.

In Comparative Example 6, since the relaxation rate was too large, the yarn path was not stable at all, and it was difficult to apply a uniform heat treatment to the yarn, resulting in large uneven shrinkage.

Further, in Comparative Example 7, since the intrinsic viscosity was as low as 0.49, which was out of the range of the present invention, a superdraw occurred during stretching, resulting in poor stretchability.

[0052]

[Table 2]

[0053]

The high shrinkage polyester short fiber of the present invention has a rich swelling, a soft feeling, and a light fastness after dyeing by being blended or woven with a low shrinkage short fiber, and has a shrinkage. The rate of change over time is small,
A spun yarn woven fabric that can maintain the swelling feeling over a long period of time and has excellent liveliness can be obtained.

Claims (8)

[Claims] 1. The boiling water shrinkage is 20% or less, the dry heat shrinkage at 160 ° C. after boiling water treatment is 12 to 40%, and the boiling water shrinkage is 18% after boiling water treatment.
A high-shrinkable polyester short fiber having a dry heat shrinkage of 0 ° C. of 15 to 45% and a change with time of 15% or less. 2. Isophthalic acid and 2.2 bis {4-
2. The high-shrinkable polyester short fiber according to claim 1, comprising a copolymerized polyester containing (2-hydroxyethoxy) phenyl} propane as a copolymer component and satisfying the following formulas I, II and III simultaneously. P (a) + 1.5 × P (b) ≧ 8.5 −−− IP (a) + P (b) ≦ 18.0 −−−− II 1.0 ≦ P (b) ≦ 5.5 --- III (wherein, P (a) is the mole fraction (%) of isophthalic acid with respect to all the acid components in the copolymerized polyester, and P (b) is the mole fraction of all the glycol components in the copolymerized polyester. 2.
It is the mole fraction (%) of 2-bis {4- (2-hydroxyethoxy) phenyl} propane. ) 3. The crystallinity measured by a density method is 15 to 30.
% Of the high-shrinkable polyester short fiber according to claim 1. 4. The high-shrinkable polyester short fiber according to claim 1, wherein the birefringence measured by a compensator method is 110 × 10 ^{−3 to} 145 × 10 ^−3. . 5. The high-shrinkable polyester short fiber according to claim 1, wherein the shrinkage stress is 150 mg / d or more. 6. The high-shrinkable polyester short fiber according to claim 1, wherein the intrinsic viscosity is 0.52 or more. 7. The high-shrinkable polyester short fiber according to claim 1, wherein the cross-sectional shape is three or more leaves and the degree of deformation is 1.2 or more. 8. Isophthalic acid and 2.2 bis {4-
(2-Hydroxyethoxy) phenyl @ propane is used as a copolymer component, and the following formulas I, II, and III are simultaneously satisfied, and the drawn copolyester fiber having an intrinsic viscosity of 0.52 or more is -2.
A method for producing a high-shrinkable polyester short fiber, comprising heat-treating at 120 to 180 ° C. for 2 seconds or more at a relaxation rate of ５5%. P (a) + 1.5 × P (b) ≧ 8.5 −−− IP (a) + P (b) ≦ 18.0 −−−− II 1.0 ≦ P (b) ≦ 5.5 --- III (wherein, P (a) is the mole fraction (%) of isophthalic acid with respect to all the acid components in the copolymerized polyester, and P (b) is the mole fraction of all the glycol components in the copolymerized polyester. 2.
It is the mole fraction (%) of 2-bis {4- (2-hydroxyethoxy) phenyl} propane. )