KR20100070202A - Composite fibers of high elastic polyester with being improved dyeing and method of manufacturing the same - Google Patents

Abstract

PURPOSE: High elasticity polyester composite fiber of which dyeing property is improved and a manufacturing method thereof are provided to make high elasticity polyester composite fiber gaining latent crimp fiber by controlling a spinning, a drawing, and a twisting processes. CONSTITUTION: High elasticity polyester composite fiber of which dyeing property is improved includes polytrimethylene terephthalate and modified polyethylene terephthalate. A manufacturing method of the high elasticity polyester composite fiber includes the following steps: manufacturing reformed PET; melting the PTT and modified PET; acquiring the composite fiber by spinning a melted material through a discharge-hole; and twisting and drawing the composite fiber with a TCS device at a drawing temperature of 150-200°C.

Description

Composite fibers of high elastic polyester with being improved dyeing and method of manufacturing the same

The present invention relates to the production of polyester-based composite fibers having latent crimping properties, and in particular, a fiber and a composite fiber of polytrimethylene terephthalate (PTT) and modified polyethylene terephthalate (PET), which are heterogeneous polyester polymers. It relates to a manufacturing method.

Recently, in the field of sportswear and general apparel used, the spandex market characterized by elasticity has been steadily growing as the demand for fabrics requiring high elasticity and materials for differentiated fabrics different from existing touches has increased. However, in the case of spandex, there is a problem in alkali resistance, there is a problem in form stability, etc., the spandex yarn can not be used alone, there is a disadvantage that a separate covering process is required. As a result, relatively thick fabrics have to be obtained, which limits the market demand for thinner fabrics. In order to overcome the shortcomings of spandex, stretchable polyethylene terephthalate (PET) having different viscosities is produced by a method of expressing a crimp due to a heat shrinkage difference imparted during fabrication by composite spinning in a side-by-side manner. Latent crimped fibers have been proposed.

The latent crimped fiber is composed of two types of polymers with different thermal contraction properties in side-by-side or sheath-core composites, and then heat-shrinkable by applying heat in a spinning or stretching process. It is a fiber that gives a high elasticity by the principle similar to the spring by making the coil shape physically by the difference. The elasticity is less than the existing spandex fiber, but the disadvantages of the above-mentioned spandex is a lot of latent crimped fibers excellent in alkali resistance and shape stability, easy to dyeing and post-processing.

In Japanese Patent Laid-Open Nos. 10-72732 and 9-209217, methods of using two kinds of polyethylene terephthalate (PET) having extreme viscosity differences, and Japanese Patent Laid-Open No. 3-161519 and Japanese Laid-Open Patent No. 9 -414234 discloses a method for producing a polyester-based latent crimp expressive fiber using a highly shrinkable copolymerized polyethylene terephthalate (PET), and this type of latent crimp is used with a significantly lower elasticity than spandex. This was limited.

As an alternative to solve this problem, a composite fiber using polytrimethylene terephthalate (PTT) and polyethylene terephthalate (PET) is described in US Pat. No. 3,671,379, and the elasticity of polyester latent crimped fibers is higher than that of conventional fibers. In addition, the demand for this is increasing. However, the latent crimps manufactured by this method have 70% or less of fixability upon heat set after unloaded non-water treatment, and 20% change in modulus of elastic modulus and elongation at break of 10% before and after heat set. As described above, shape deformation occurs severely during the post-processing or after the final processing, which makes it difficult to set the conditions and stabilize the dimensions during processing the product.

In addition, the Republic of Korea Patent Publication No. 2001-0049484 proposed that the use of one of the two complex components as polytrimethylene terephthalate (PTT) can solve the problem of excessive tightening due to excellent soft stretch properties. In addition, in Korean Patent Laid-Open Publication No. 2004-0061352, after composite spinning of PTT and PET, the obtained composite fiber was drawn by radial direct stretching, and thus excellent physical properties such as elongation and excellent elasticity were obtained when applied to knitted fabrics. .

However, due to the difference in the dyeing property between the two polymers of the composite fiber, there is a problem due to the staining problem and tension variation for use as a fabric warp. Constraints followed. Accordingly, it has been desired to develop latent crimped fibers that can be used for warp of fabrics by controlling the dyeing and tension variations between two polymers, but also have a high elasticity recovery rate and elongation recovery rate, which is a recent trend of fabrics.

In order to solve the above problems, an object of the present invention is to reduce the difference in dyeing and dyeing temperatures between two polymers, and to produce latent crimped fibers having excellent crimping properties and elongation recovery rate through spinning, drawing and flammable process control. It is to provide a method and a method for producing a composite fiber having a dense, soft and excellent elongation recovery using the same.

It is also an object of the present invention to control the spinning, drawing and flammable conditions to control the crimping properties, the maximum stress temperature, the maximum stress value in the yarn to provide a composite fiber and a method of manufacturing the improved elastic properties than the existing potential crimps have.

In addition, an object of the present invention is to produce a warp fabric, warp knitted fabric, circular knitted fabric using a high-stretch polyester composite fiber with improved dyeability and a method for producing the same.

In order to achieve the above object, the present invention includes a polyester-based composite fiber, including polytrimethylene terephthalate (PTT) and modified polyethylene terephthalate (PET), the modified PET 100 parts by weight of the total modified PET A composite fiber further comprising 1 to 10 parts by weight of polyethylene glycol (PEG), (1) the elongation at break is 25% to 40%, (2) the maximum stress value of dry heat shrinkage stress is 0.3 to 0.5 G / D, ( 3) The dry heat shrinkage at the maximum stress expression temperature is 150 to 200 ℃, (4) the length of the shrinkage after the LEESONA measurement is 23 to 30cm, (5) the elasticity recovery is characterized in that the elastic recovery rate is 25 to 45% It provides a high stretch polyester composite fiber.

In another aspect, the present invention provides a high-stretch polyester composite fiber with improved dyeability that the modified PET further comprises 1 to 10 parts by weight of DMS (dimethyl-5-sulfoisophthalate sodium salt) based on 100 parts by weight of the total modified PET. .

In another aspect, the present invention provides a high-stretch polyester composite fiber with improved dyeability of the composite fiber side-by-side type.

In addition, the present invention is a high-stretch polyester with improved dyeability, characterized in that the intrinsic viscosity (IV) of the polymer PTT is 0.90 to 1.10dl / g, the intrinsic viscosity (IV) of the modified PET is 0.50 to 0.70dl / g It provides a composite fiber.

In another aspect, the present invention provides a high-stretch polyester composite fiber with improved dyeability, characterized in that the ratio of the composite fiber is 45:55 to 50:50 PTT and modified PET.

In addition, the present invention is a method for producing a polyester-based composite fiber, the modified polyethylene terephthalate (PET) to 100 parts by weight of polyethylene glycol (PEG) by adding 1 to 10 parts by weight to prepare a modified PET; Melting polytrimethylene terephthalate (PTT) and the modified polyethylene terephthalate (PET); Spinning the melt at a spinning speed of 2000 to 3000 m / min through a discharge hole to obtain a composite fiber; And it provides a method for producing a high-stretch polyester composite fiber with improved dyeability to prepare a drawn using a TCS apparatus at a stretching temperature of 150 to 200 ℃ the stretched and twisted the obtained composite fiber.

In another aspect, the present invention is a method for producing a high-stretch polyester composite fiber with improved dyeing property of adding 1 to 10 parts by weight of DMS (dimethyl-5-sulfoisophthalate sodium salt) based on 100 parts by weight of the total modified PET. To provide.

In another aspect, the present invention provides a method for producing a high-stretch polyester composite fiber with improved dyeability prepared by composite spinning the composite fiber in a side-by-side type.

In addition, the present invention is a high-stretch polyester with improved dyeability, characterized in that the intrinsic viscosity (IV) of the polymer PTT is 0.90 to 1.10dl / g, the intrinsic viscosity (IV) of the modified PET is 0.50 to 0.70dl / g It provides a method for producing a composite fiber.

In another aspect, the present invention provides a method for producing a high-stretch polyester composite fiber with improved dyeability, characterized in that the ratio of the composite fiber PTT and modified PET is 45:55 to 50:50.

In another aspect, the present invention provides a method for producing a high-stretch polyester composite fiber with improved dyeability, characterized in that the draw ratio is 1.5 to 2.0 times in the stretching process.

In another aspect, the present invention provides a fabric characterized in that the fiber and the fiber produced by the method using a twisted yarn or lead-free, and is manufactured using a warp or weft yarn.

The composite fiber produced by the present invention exhibits uniform and excellent stretch characteristics than the existing latent crimp-type fibers and has a very excellent workability due to a stable process.

In addition, the composite fiber and its manufacturing method according to the present invention produces a latent crimp composite fiber having excellent crimping properties and excellent elongation recovery rate through stable spinning process, drawing and flammable process control, and has a fine, soft and excellent elongation recovery rate There is an effect that can produce a fabric.

In addition, the composite fiber according to the present invention and a method for manufacturing the same can be used for inclination because the dyeing rate and dyeing temperature between PTT and modified PET can be similar, and can be dyed at 100 to 110 ° C. and also with wool fibers. Can be used interchangeably.

In addition, the composite fiber and the manufacturing method thereof according to the present invention can be attached to the TCS (tension control device) when manufacturing the twisted yarn to produce a composite fiber under uniform tension to control the dyeing deviation and tension deviation can be used for warp in the fabric In addition to being possible, it can also be used for warp knitting and knitting.

In addition, the composite fiber according to the present invention is a polyester-based latent crimp, the composite fiber has an elastic recovery of 25 to 45%, the fabric made of the composite fiber has an effect of having more than 30% stretch.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. First, it should be noted that in the drawings, the same components or parts denote the same reference numerals as much as possible. In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted in order not to obscure the subject matter of the present invention.

The terms " about ", " substantially ", etc. used to the extent that they are used herein are intended to be taken to mean an approximation to or in the numerical value of the manufacturing and material tolerances inherent in the meanings mentioned, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure.

As used herein, the term "fabric" is used to include all articles, nonwoven fabrics and fibrous webs produced by weaving or knitting.

The present invention proposes a latent crimped composite fiber having improved dyeing property and excellent crimping properties and elongation recovery using polytrimethylene terephthalate (PTT) and modified polyethylene terephthalate (PET), which are heterogeneous polyesters, and a method of manufacturing the same. .

The present invention is characterized in that the first component is polytrimethylene terephthalate (PTT) and the second component is modified polyethylene terephthalate (PET). The modified PET here is polyethylene glycol (PEG) alone or polyethylene glycol (PEG) and DMS (dimethyl-5-sulfoisophthalate sodium salt). 5-Sulfoisophthalate Sodium Salt) is represented by the following formula.

When the modified PET is added to the polyethylene glycol alone, 1 to 10 parts by weight of PEG is added to 100 parts by weight of the total modified PET, and polyethylene glycol (PEG) and DMS (dimethyl-5-sulfoisophthalate) are added. When adding sodium salt (Dimethyl-5-Sulfoisophthalate Sodium Salt), 1 to 10 parts by weight of PEG and 1 to 10 parts by weight of DMS (dimethyl-5-sulfoisophthalate sodium salt) are added to 100 parts by weight of the total modified PET. In the production of modified PET, a heat stabilizer, a reaction initiator, a complementary agent, an antifoaming agent, etc. are added, and the dyeing property of the two polymers (PTT and PET) is enhanced by increasing the dyeing property of the PET by adding the above-mentioned substance PEG alone or PEG and DMS. And dyeing temperature and the like.

The ratio of PTT and PET of the present invention is 45:55 to 50:50, but when the ratio of PTT exceeds 50, there is a disadvantage in that elasticity is reduced.

The intrinsic viscosity (IV) of the PTT is 0.90 to 1.10 dl / g, and the intrinsic viscosity (IV) of the modified PET is preferably 0.50 to 0.70 dl / g. When the intrinsic viscosity is less than the above range, there is a problem that the fluidity is increased, the crimping property is decreased, and the adhesion between the interfaces is significantly decreased. In addition, when the modified PET exceeds the above range and the viscosity difference with the PTT is small, there is a problem that the elasticity of the composite fiber is poor. When testing the stretch properties of the yarn and fabric by various combinations of the viscosity of the polymer of the PTT and the modified PET, it is advantageous to increase the viscosity difference between the two polymers.

1 is a schematic diagram of a composite spinning apparatus used in the present invention. PTT and modified PET are spun through separate discharge holes through a melting step. The individual fibrous polymer spun through the discharge hole with the PTT and the modified PET to obtain a composite fiber in the side-by-side type just below the spinneret. The spinning speed of the polymer to be spun is 1600 to 3300m / min and preferably the spinning speed is 2000 to 3000m / min. When the spinning speed exceeds the above range, there is a problem in spinning workability, and when the spinning speed is below the above range, a change in properties of the partially drawn yarn (POY) occurs, making it difficult to establish stable manufacturing conditions.

Figure 2 is a schematic diagram of an apparatus showing the stretching and burning process used in the present invention. The stretching process of the present invention occurs between the feed roller 1 and the feed roller 2, the heater temperature, the draw ratio is a factor that greatly affects the crimp characteristics of the composite fiber, it is important to set the appropriate conditions.

The stretching temperature of the present invention can be seen as the temperature of the heater-1, the stretching temperature is preferably set to 150 to 200 ℃. The crimping characteristics can be adjusted by adjusting the maximum stress expression temperature through the temperature control of the heater-1. If the stretching temperature is less than 150 ℃ fiber uniformity is poor, the quality is in a bad state, if the stretching temperature exceeds 200 ℃ workability is poor and the fiber is easily broken.

The draw ratio of the present invention is 1.4 to 2.2 times, preferably 1.5 to 2.0 times the draw ratio. In the present invention, when the draw ratio is less than 1.4 times, the crimping property is decreased, and when the draw ratio exceeds 2.2 times, the draw ratio has an adverse effect on the workability of the sacrificial yarn, so an appropriate draw ratio should be selected.

In addition, the present invention can attach a separate TCS (tension control system) in the combustion process to set the uniform tension between the yarns at the time of combustion can reduce the tension variation between yarns, thereby minimizing the yarn shrinkage variation can do.

The polyester-based latent crimping yarn according to the present invention adjusts the maximum stress starting temperature to 80 to 100 ° C. by appropriately adjusting the spinning conditions, the spinning speed at the time of stretching and burning, the stretching ratio, the temperature of the heater-1, and the tension by the TCS device. , The maximum stress expression temperature is 140 to 200 ℃, the maximum stress value is adjusted to 0.2 to 0.6g / d level, the crimping characteristics of the yarn and the elastic recovery rate can be appropriately prepared composite fiber.

The composite fiber prepared by the above manufacturing method has an elongation at break of 25% to 40%, a maximum stress value of dry heat shrinkage stress of 0.3 to 0.5 G / D, and a temperature of 150 to 200 ° C. at dry heat shrinkage maximum stress, and measuring LEESONA. After the shrinkage is characterized in that the length is 23 to 30cm.

Figure 3 is a SEM photograph showing the cross-section and side shape of the high-strength polyester composite fiber finally produced in the present invention. The side-by-side type of latent crimped composite fiber manufactured by the above method has an elastic recovery rate of 25 to 45%, and has a characteristic of a fabric having elasticity of 30% or more.

In addition, the composite fiber produced by the manufacturing method of the present invention can adjust the dyeing deviation and tension deviation, can be used for warp yarn or lead-free in the fabric, as well as can be used to extend the use in warp knitted and knitted fabrics have.

Hereinafter, embodiments of the present invention will be described in detail. Experimental results of each Example and Comparative Examples can be summarized in Table 1 below.

Example 1

1.0 parts by weight of PEG (molecular weight 1000) and DMS (Dimethyl-5-Sulfoisophthalate Sodium Salt) with respect to PTT having a thickness of 6.0 denier and total denier of 290 denier and intrinsic viscosity of 1.10 dl / g and 100 parts by weight of modified PET. ), Containing 2.0 parts by weight of latent crimped composite filament yarn composed of modified PET having an intrinsic viscosity of 0.63 dl / g at a spinning speed of 2200 M / min to produce partial oriented yarn, and then in a separate drawing and twisting process, the TCS apparatus The polyester latent crimp yarn was manufactured under the uniform tension control using a yarn speed (speed of feed roller 2 in Fig. 2) 500 M / min, a temperature of 150 ° C. of heater-1, a belt angle of 100 °, and a draw ratio of 2.0. The polyester latent crimps prepared in this way have a thickness of 3.1 denier and a total denier of 150 denier. The yarn thus prepared was twisted with 800TM and used as warp and weft yarns to weave into plain weave in a waterjet loom, and then the dyeing process was performed according to normal processing conditions. Physical properties such as elongation rate and elongation recovery rate of dyed fabrics were measured 10 times in accordance with KSK standard.

Example 2

Except that the prepared yarn was lead-free was prepared in the same manner as in Example 1.

Example 3

The yarn was prepared by twisting the knitted yarn with 800 TM and then knitted into a knitted fabric, and was prepared in the same manner as in Example 1 except that the dyeing was performed according to the usual processing conditions.

Example 4

It manufactured like Example 1 except having set draw ratio to 1.5.

Example 5

It was prepared in the same manner as in Example 1 except that 5.0 parts by weight of PEG (molecular weight 1000) was contained with respect to 100 parts by weight of modified PET to be made of modified PET having an intrinsic viscosity of 0.70 dl / g.

Example 6

It was prepared in the same manner as in Example 2 except that 5.0 parts by weight of PEG (molecular weight 1000) was contained with respect to 100 parts by weight of modified PET, and was composed of modified PET having a high oil viscosity of 0.70 dl / g.

Example 7

It was prepared in the same manner as in Example 3, except that 5.0 parts by weight of PEG (molecular weight 1000) was contained with respect to 100 parts by weight of modified PET, and was composed of modified PET having an intrinsic viscosity of 0.70 dl / g.

Example 8

It was prepared in the same manner as in Example 1 except that 5.0 parts by weight of PEG (molecular weight 1000) was contained with respect to 100 parts by weight of modified PET, and composed of modified PET having an intrinsic viscosity of 0.70 dl / g and a draw ratio of 1.5.

Comparative Example 1

The preparation was carried out in the same manner as in Example 1, except that no separate TCS device was used in the drawing and drawing process.

Comparative Example 2

Except that the prepared yarn was lead-free was prepared in the same manner as in Comparative Example 1.

Comparative Example 3

The prepared yarn was twisted with 800TM to be knitted into a knitted fabric, and then manufactured in the same manner as in Comparative Example 1 except that the dyeing was performed according to the usual processing conditions.

Comparative Example 4

It was prepared in the same manner as in Example 1 except that the composite fiber was prepared using pure PET without modifying the PET.

Comparative Example 5

It was prepared in the same manner as in Example 1 except that 12.0 parts by weight of PEG (molecular weight 1000) was contained with respect to 100 parts by weight of modified PET, and was composed of modified PET having an intrinsic viscosity of 0.75 dl / g.

Comparative Examples 6 and 7

Except for setting the draw ratio to 2.5, it was prepared in the same manner as in Example 1 and Example 5.

Comparative Examples 8 and 9

It manufactured similarly to Example 1 and Example 5 except having set draw ratio to 1.2, respectively.

division PTT Intrinsic Viscosity
(dl / g) Modified PET Intrinsic Viscosity (dl / g) Extension ratio (times) burglar
(G / D) Shindo
(%) Elastic recovery
(%) LEESONA
(cm) Maximum stress value
(G / D) Maximum stress temperature
(℃) Fabric elongation rate
(%) Fabric recovery rate (%)
Dyeability Example 1 1.1 0.63 2.0 3.0 36 43 27 0.44 168 38 97 Great Example 2 1.1 0.63 2.0 3.4 38 42 25 0.49 175 36 96 Great Example 3 1.1 0.63 2.0 3.3 35 40 27 0.36 172 33 95 Great Example 4 1.1 0.63 1.5 3.2 35 42 27 0.43 165 36 95 Great practice
Example 5 1.1 0.70 2.0 3.3 29 40 26 0.34 178 35 97 Great practice
Example 6 1.1 0.70 2.0 3.5 36 38 25 0.38 175 38 95 Great practice
Example 7 1.1 0.70 2.0 3.5 30 42 24 0.48 164 32 95 Great practice
Example 8 1.1 0.70 1.5 3.3 32 35 28 0.32 174 33 96 Great Comparative Example 1 1.1 0.63 2.0 3.0 22 26 20 0.31 167 29 88 Bad compare
Example 2 1.1 0.63 2.0 3.1 23 23 21 0.28 162 28 87 Bad compare
Example 3 1.1 0.63 2.0 3.0 22 20 19 0.32 164 28 89 Bad compare
Example 4 1.1 0.63 2.0 2.9 24 22 18 0.33 160 30 85 usually compare
Example 5 1.1 0.75 2.0 3.1 23 25 18 0.29 160 28 90 Bad compare
Example 6 1.1 0.63 2.5 3.1 20 23 20 0.31 158 26 86 Bad compare
Example 7 1.1 0.63 2.5 3.2 20 23 21 0.27 159 25 88 Bad compare
Example 8 1.1 0.63 1.2 3.0 23 22 22 0.27 164 26 88 usually compare
Example 9 1.1 0.70 1.2 3.0 24 20 20 0.29 163 30 89 usually

※ Test Methods

(1) Measurement of strength and elongation

The fineness of the yarn was obtained by winding 90m of a 1m skein at a time of rotation and measuring the weight and converting it to 9000m. The strength and elongation of the fibers were measured using an automatic tensile tester (Textechno, Inc.) at a rate of 50 cm / min and a gripping distance of 50 cm.

(2) elastic recovery rate

Measured according to ASTM D 6720, the sample is adjusted by the number of revolutions to obtain a 5000 de sine, and immersed in water at 100 ℃ for 15 minutes to measure L1, L2 as follows.

      L1: Measured after applying 30g + 1000g load. (stress & relax 3 reps)

      L2: Measured 30 seconds after removing 1000 g of load.

     Calculation: elastic recovery rate = (L1-L2) / L2 × 100

(3) the maximum stress temperature and the maximum stress value

It measured using the thermal stress measuring apparatus (KE-2: Kanebo Engineering make), cut the fiber into 22 cm, made it into the 10 cm ring, and installed it in the measuring device. The initial load at the time of measurement was measured on 0.067 G / D and the conditions of the temperature increase rate of 2 degree-C / sec, and the temperature change of thermal stress was described in the chart. From the reading of this peak, the maximum stress temperature and the maximum stress value (G / D) were measured.

(4) LEESONA shrink length

The initial length of the sample is (20.5 ÷ 0.0016 ÷ de ÷ 2) m (m), and it is wound on a skein of 1m in one rotation and the both ends are connected to make the initial length 50cm, and 20.5g super load is applied. The length was measured by heat-processing for 10 minutes in warm water of (± 2 ° C) and leaving it for 3 to 5 minutes (until the water drops did not fall).

(5) elongation rate, elongation recovery rate of fabric

The elongation of the fabric was measured 10 times using the method of KSK 0352 5.2.2.

The stretch recovery rate of the fabric was measured 10 times by the method of KSK 0541.

(6) dyeability evaluation

The samples are knitted and then dried for 30 minutes at a dyeing temperature of 100 ° C, followed by natural drying. When the dyeing between the two polymers is visually inspected by an expert, it is excellent if more than 8 out of 10 are judged to be uniform. When people judge that the dyeability is uniform, usually 5 or less people are classified as defective when judged that the dyeability between the two polymers is uniform.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. It will be clear to those who have knowledge of.

1 is a schematic diagram of a composite spinning apparatus used in the present invention.

Figure 2 is a schematic diagram of a device showing the stretching and burning process used in the present invention.

Figure 3 is a cross-sectional and side view of the high-stretch polyester composite fiber is finally dyed improved in the present invention.

    * Explanation of symbols for the main parts of the drawings

1: guide tube 2: feed roller 0

3: feed roller 1 4: heater-1

5: cooling plate 6: twister belt

7: feed roller 2 8: heater-2

9: feed roller 3 10: oil roller

11: winder 12: air nozzle

13: TCS (Tension Control System) device

Claims (12)

In the polyester-based composite fiber, Polytrimethylene terephthalate (PTT) and modified polyethylene terephthalate (PET), the modified PET is a composite fiber further comprises 1 to 10 parts by weight of polyethylene glycol (PEG) based on 100 parts by weight of the total modified PET, (1) the elongation at break is 25% to 40%, (2) the maximum stress value of dry heat shrinkage stress is 0.3 to 0.5 G / D, (3) the dry heat shrinkage maximum stress expression temperature is 150 to 200 ℃, (4) the contracted length after the LEESONA measurement is 23 to 30 cm, and (5) High stretch polyester composite fiber with improved dyeability, characterized in that the elastic recovery rate is 25 to 45%. The method of claim 1, The modified PET is a high-stretch polyester composite fiber with improved dyeing property further comprises 1 to 10 parts by weight of DMS (dimethyl-5-sulfoisophthalate sodium salt) based on 100 parts by weight of the total modified PET. The method according to claim 1 or 2, The composite fiber is a high-stretch polyester composite fiber with improved dyeability of the side-by-side type. The method according to claim 1 or 2, The high-stretch polyester composite fiber with improved dyeability, characterized in that the intrinsic viscosity (IV) of the polymer PTT is 0.90 to 1.10 dl / g, and the intrinsic viscosity (IV) of the modified PET is 0.50 to 0.70 dl / g.  The method according to claim 1 or 2, The ratio of the composite fiber is a high stretch polyester composite fiber with improved dyeability, characterized in that the PTT and modified PET is 45:55 to 50:50. In the method for producing a polyester-based composite fiber, Preparing modified PET by adding 1 to 10 parts by weight of polyethylene glycol (PEG) based on 100 parts by weight of modified polyethylene terephthalate (PET); Melting polytrimethylene terephthalate (PTT) and the modified polyethylene terephthalate (PET); Spinning the melt at a spinning speed of 2000 to 3000 m / min through a discharge hole to obtain a composite fiber; And Method for producing a high-stretch polyester composite fiber with improved dyeability to prepare the obtained composite fiber at a stretching temperature of 150 to 200 ℃ during stretching and twisting using a TCS device. The method of claim 6, The modified PET is a method for producing a highly stretched polyester composite fiber with improved dyeing property by adding 1 to 10 parts by weight of DMS (dimethyl-5-sulfoisophthalate sodium salt) based on 100 parts by weight of the total modified PET. The method according to claim 6 or 7, The composite fiber is a method of producing a high-stretch polyester composite fiber with improved dyeability prepared by composite spinning in a side-by-side type. The method according to claim 6 or 7, Preparation of highly stretched polyester composite fiber with improved dyeability, characterized in that the intrinsic viscosity (IV) of the polymer PTT is 0.90 to 1.10 dl / g, and the intrinsic viscosity (IV) of the modified PET is 0.50 to 0.70 dl / g. Way.  The method according to claim 6 or 7, The ratio of the composite fiber is a method for producing a high-stretch polyester composite fiber with improved dyeing, characterized in that the PTT and modified PET is 45:55 to 50:50. The method according to claim 6 or 7, Method for producing a high-stretch polyester composite fiber with improved dyeability, characterized in that the draw ratio is 1.5 to 2.0 times in the stretching step. A fabric prepared by using the fiber according to claim 1 or 2 or the fiber according to claim 6 or 7 as twisted yarn or lead-free and using as warp yarn or weft yarn.

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