Polyester composite fiber, polyester false-twist textured yarn, and production methods therefor

Abstract

An object of the invention is to provide a polyester conjugate fiber and a textured yarn, which have a small initial modulus and also have high crimping performance even before a boiling water treatment, in which the difference in crimping characteristics before and after the boiling water treatment is small, as well as production methods therefor. In the invention, a polyester conjugate fiber which includes polyester components having different intrinsic viscosities bonded together in a side-by-side manner, a bonded manner, or an eccentric sheath-core manner over the entire length of the fiber, and simultaneously satisfies the following requirements (a) to (d), is subjected to draw false-twist texturing. (a) The ratio of crystallization heat quantity at elevated temperature of the conjugate fiber is 10% to 60% relative to the completely amorphous state, (b) the elongation at break of the conjugate fiber is 60 to 200%, (c) the breaking strength (cN / dtex) × elongation1 / 2 (%) of the conjugate fiber ≥ 10, and (d) the peak temperature of the thermal stress of the conjugate fiber is equal to or lower than the glass transition temperature + 50°C of the polyester component having a higher glass transition temperature among the polyester components constituting the conjugate fiber, and the peak value of the thermal stress of the conjugate fiber is 0.05 to 0.8 cN / dtex.

Description

Technical Field

[0001] The present invention relates to a polyester conjugate fiber and a polyester false twisted textured yarn, as well as production methods therefor. More specifically, the invention stably provides a low-crystallinity, high-elongation partially oriented polyester conjugate fiber, and also relates to a polyester conjugate fiber false twisted textured yarn obtained by draw false-twist texturing using the above conjugate fiber, which has a small initial modulus and also has high crimping performance even before a boiling water treatment, in which the difference in crimping characteristics before and after the boiling water treatment is small, and also to production methods therefor.Background Art

[0002] Polytrimethylene terephthalate (hereinafter sometimes referred to as "PTT"), which is obtained by the polycondensation of a lower alcohol ester of terephthalic acid such as terephthalic acid or dimethyl terephthalate with trimethylene glycol (1,3-propanediol), is an innovative polymer in that fibers made thereof have properties similar to those of polyamide, such as low modulus (soft texture), excellent elastic recovery, and dyeability, together with performance similar to that of polyethylene terephthalate (hereinafter sometimes referred to as "PET") fibers, including light resistance, heat-setting properties, dimensional stability, and low water absorption. Taking advantage of these characteristics, such fibers have been applied to BCF carpets, brushes, tennis strings, and the like.

[0003] One of the fiber forms that can make the most of the above characteristics of PTT fibers is a false twisted textured yarn. This is because, as disclosed in JPH11-093026A, JP2005-264424A, JP2015-007306A, etc., false twisted textured yarns of PTT fibers have rich elastic recovery and softness compared to fibers having a structure similar to PTT, such as PET fibers and like polyester fibers, for example, and such a yarn is thus extremely excellent as a raw yarn for stretchiness.

[0004] However, although false twisted textured yarns using PTT fibers as described above have excellent elastic recovery and softness, they are prone to yarn breakage, and thus it has been impossible to enhance the crimping performance. For this reason, it has been difficult to produce a PTT false twisted textured yarn that has excellent crimping characteristics, has high fineness, and serves as a high-multifilament.

[0005] Meanwhile, various conjugate fibers having a side-by-side arrangement of PTT components have been proposed. In particular, as a side-by-side type conjugate fiber using polytrimethylene terephthalate and a false twisted textured yarn thereof, JP2005-264424A (PTL 1) is known, which has high crimping performance. Meanwhile, because the crimping occurs through a boiling water treatment, the crimp-developing ability during woven fabric binding is low, or the crimp is easily weakened by external force. Therefore, it has been impossible to sufficiently develop the function as a stretch fiber.

[0006] In addition, JP2003-301341A (PTL 2) discloses that when a side-by-side type or eccentric sheath-core type conjugate fiber drawn yarn composed of two kinds of PTTs having different intrinsic viscosities is subjected to false-twist texturing and heat-setting, a false twisted textured yarn of a PTT conjugate fiber having excellent stretchability and high fabric quality can be obtained. However, heat-setting reduces the crimp, and this fiber does not have sufficient stretchability either.Citation ListPatent Literature

[0007] PTL 1: JP2005-264424A PTL 2: JP2003-301341A Summary of InventionTechnical Problem

[0008] The invention has been accomplished against the above background. An object thereof is to provide a polyester conjugate fiber and a textured yarn, which have a small initial modulus and also have high crimping performance even before a boiling water treatment, in which the difference in crimping characteristics before and after the boiling water treatment is small, as well as production methods therefor.Solution to Problem

[0009] The present inventors have conducted extensive research to achieve the above object. As a result, they have found the above problems can be solved by subjecting a low-crystallinity, high-elongation partially oriented polyester conjugate fiber to draw false-twist texturing, and thus accomplished the invention.

[0010] That is, the invention provides: 1. a polyester conjugate fiber, being a conjugate fiber including polyester components having different intrinsic viscosities bonded together in a side-by-side manner, a bonded manner, or an eccentric sheath-core manner over the entire length of the fiber, in which the conjugate fiber simultaneously satisfies the following requirements (a) to (d): (a) the ratio of crystallization heat quantity at elevated temperature of the conjugate fiber is 10% to 60% relative to the completely amorphous state; (b) the elongation at break of the conjugate fiber is 60 to 200%; (c) the breaking strength (cN / dtex) × elongation 1 / 2< (%) of the conjugate fiber ≥ 10; and (d) the peak temperature of the thermal stress of the conjugate fiber is equal to or lower than the glass transition temperature + 50°C of the polyester component having a higher glass transition temperature among the polyester components constituting the conjugate fiber, and the peak value of the thermal stress of the conjugate fiber is 0.05 to 0.8 cN / dtex, 2. the polyester conjugate fiber according to the above 1, in which one of the polyester components constituting the conjugate fiber is a polyester containing 90 mol% or more of polytrimethylene terephthalate, 3. a method for producing a polyester conjugate fiber, in which polyester components having different intrinsic viscosities are melt-discharged into the form of a conjugate fiber having the polyesters bonded together in a side-by-side manner, a bonded manner, or an eccentric sheath-core manner over the entire length of the fiber, then wound up at a wind-up speed of 1,000 to 3,000 m / min on a first heating roller at the glass transition temperature - 30°C of, among the polyester components, the polyester component having a lower glass transition temperature to the glass transition temperature + 30°C of the polyester component having a higher glass transition temperature, further drawn while being heated by the first heating roller, wound around a second heating roller at 30 to 120°C, and then wound up at a speed of 2,000 to 3,300 m / min, 4. a polyester false twisted textured yarn, being crimped and formed by false-twist texturing the polyester conjugate fiber according to the above 1, and simultaneously satisfying the following requirements (1) to (4): (1) the modulus at 2% elongation is 10 cN / dtex or less; (2) 10 % ≤ Vc ≤ 50 % ; (3) 30 % ≤ Tc ≤ 70 % ; and (4) − 20 % ≤ Vc − Tc ≤ 20 % , 5. the polyester false twisted textured yarn according to the above 4, in which the false twisted textured yarn has a total fineness of 10 to 200 dtex and a tensile breaking strength of 2.0 cN / dtex or more, 6. a method for producing a polyester false twisted textured yarn, including drawing and false-twisting the polyester conjugate fiber according to the above 1, and 7. a polyester fiber structure including the polyester conjugate fiber according to the above 1 and the polyester false twisted textured yarn according to the above 4 in an amount of 5 mass% or more. Advantageous Effects of Invention

[0011] According to the invention, a low-crystallinity, high-elongation partially oriented polyester conjugate fiber can be stably provided, and, by performing draw false-twist texturing using the conjugate fiber, a polyester false twisted textured yarn having a small initial modulus and also having high crimping performance even before a boiling water treatment, in which the difference in crimping characteristics before and after the boiling water treatment is small, can be provided. Accordingly, a fiber structure having excellent stretchability can be obtained.Brief Description of Drawings

[0012] [FIG. 1] FIG. 1 is a cross-sectional view illustrating examples of the cross-sectional shape of the conjugate fiber of the invention.Description of Embodiments

[0013] Hereinafter, the invention will be described in detail.(1) Polymer Raw Material

[0014] As polymers favorable for achieving the object of the invention, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, polylactic acid, and thermoplastic polyester elastomers can be mentioned. It is possible that the molecular weights thereof are changed, and a high molecular weight polymer is used as a first component, while a low molecular weight polymer is used as a second component, or alternatively, the first component is defined as a homopolymer, while the second component is defined as a copolymer, and they are used as polyester components having different intrinsic viscosities.

[0015] In the invention, among them, a polymer containing 90 mol% or more of polytrimethylene terephthalate is preferably used as one of the components. In addition, use of a polytrimethylene terephthalate copolymer as shown below leads to an excellent balance between crimping characteristics and heat resistance and thus is still more preferable. That is, without impairing the effects of the invention, a polytrimethylene terephthalate polymer is copolymerized with an acid component such as isophthalic acid, succinic acid, adipic acid, 2,6-naphthalenedicarboxylic acid, or 5-sulfoisophthalic acid tetrabutylphosphonium salt, a glycol component such as 1,4-butanediol, 1,6-hexanediol, or cyclohexanedimethanol, ε-caprolactone, 4-hydroxybenzoic acid, polyoxyethylene glycol, polytetramethylene glycol, or the like within a range of less than 10 mass%.

[0016] In addition, as necessary, the above polymers may have copolymerized or mixed therewith various additives such as delusterants, heat stabilizers, antifoaming agents, color-adjusting agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents, and fluorescent brighteners, for example.

[0017] In the case where a polytrimethylene terephthalate polymer is used in the invention, the intrinsic viscosity [η] is 0.5 to 1.6, preferably 0.6 to 1.5. It is more preferably 0.7 to 1.4. In the case where the intrinsic viscosity is less than 0.5, because the molecular weight of the polymer is too low, strength development may be difficult, and conversely, in the case where the intrinsic viscosity is more than 1.6, because of the low flowability, the spinnability of low-viscosity polytrimethylene terephthalate may be impaired, causing breakage during spinning; therefore, this is undesirable.

[0018] In the invention, in the case where a polytrimethylene terephthalate polymer is used as the first component, a polyester polymer used as the second component is preferably composed of a polyester-based polymer such as polyethylene terephthalate, polybutylene terephthalate, low-molecular-weight or copolymerized polytrimethylene terephthalate, or polytetramethylene terephthalate, or a copolymer thereof. There is no problem in adding additives such as antistatic agents, flame retardants, heat resistance agents, weather resistance agents, titanium oxide, and the like to these polymers or copolymers.(2) Polyester Conjugate Fiber

[0019] In the polyester conjugate fiber of the invention, it is necessary that the above first component and second component polymers are arranged such that they are bonded together in close contact with each other over the entire length of the fiber. The arrangement of the two components is not particularly limited, and various fiber cross-sections are possible, such as a side-by-side manner, a bonded manner, and an eccentric sheath-core manner as shown in FIG. 1.

[0020] The polyester conjugate fiber of the invention can be produced by a conventionally known composite spinning method, in which polyesters having different intrinsic viscosities are extruded from spinneret holes configured such that the polyesters are melt-discharged into the form of a conjugate fiber having the polyesters bonded together in a side-by-side manner, a bonded manner, or an eccentric sheath-core manner over the entire length of the fiber. The two kinds of polyesters may be extruded in an equal volume ratio, or the proportion of each component may be appropriately varied. The ratio between the two components to be composite-spun is favorably within a range of 30 to 70 / 70 to 30. The ratio is still more preferably 40 to 60 / 60 to 40. In the case where the polytrimethylene terephthalate component is 70% or more, crimpability improves, but the strength as a conjugate fiber may decrease. Meanwhile, in the case where the polytrimethylene terephthalate component is less than 30%, crimpability may be insufficient.

[0021] In addition, with respect to the melt viscosity, the difference in melt viscosity between the first component and the second component is desirably 200 poise (measured at 290°C and a shear rate of 7,780 cm -1< ) or more and 3,000 poise or less. The difference is more preferably 250 to 2,500 poise, and still more preferably 300 to 2,000 poise. When the viscosity difference is less than 200 poise, crimp development may not be observed, while when it is more than 3,000 poise, in the case where the two components with different melt viscosities are composite-spun immediately below the discharge holes, a kneeing phenomenon, in which the yarn bends toward the higher melt viscosity side immediately below the discharge holes, may occur, causing problems with operability.

[0022] The occurrence of the above kneeing phenomenon not only deteriorates the yarn quality, but also interferes with spinnability, and sometimes makes production impossible due to adhesion to the spinneret plate. A method to prevent kneeing is to tailor the spinneret holes. For example, as shown in British Patent No. 965729, a method in which the spinneret holes are previously bent in the direction opposite to the kneeing direction, and the polymer is discharged vertically from the spinneret face, is also effective in the production of the polyester conjugate fiber of the invention.

[0023] The method for producing the polyester conjugate fiber will be described in further detail. In order to remove moisture as much as possible from the polyester chips composed of the first component and the second component and suppress hydrolysis, the chips are dehumidified to a moisture content of to 0.01 mass% or less using a chip drying apparatus such as those known in the conventional polyester conjugate fiber production. Subsequently, the polymers that have been melted through a melt extruder, such as an extruder or a silver plate melter, are discharged from a spinneret having a nozzle provided with the same number of holes as the target filament count, and, while being cooled and solidified by cooling air blown below the spinneret, taken up by a godet roller, and wound up on a bobbin using a winder.

[0024] Incidentally, in the above polyester conjugate fiber, when obtaining a partially oriented yarn (POY) for making the below-described false twisted textured yarn, the fiber is wound up at a wind-up speed of 1,000 to 3,000 m / min on a first heating roller at the glass transition temperature - 30°C of, among the polyester components, the polyester component having a lower glass transition temperature (hereinafter sometimes referred to as Tg) to the glass transition temperature + 30°C of the polyester component having a higher glass transition temperature, further drawn to 1.0 to 3.0 times the original length while being heated by the first heating roller, wound around a second heating roller at 30 to 120°C, and then wound up at a speed of 2,000 to 3,300 m / min, whereby a partially oriented yarn of the polyester conjugate fiber can be obtained.

[0025] When the polyester conjugate fiber containing polytrimethylene terephthalate that has been melted and then solidified is wound up, in the case where winding up is performed at a speed lower than 1,000 m / min, the production efficiency is poor, and also the draw ratio becomes too high. Accordingly, the oriented crystallization excessively proceeds, and even when draw false-twist texturing is subsequently performed, the crimp does not increase.

[0026] In addition, when the polyester conjugate fiber is wound up, in the case where winding up is performed at a speed higher than 3,000 m / min, the elongation becomes too low, and thus fluff or yarn breakage is likely to occur during spinning or false-twist texturing. In addition, also at the time of draw false-twist texturing, the crimp is reduced.

[0027] Further, in the case where drawing is performed at a temperature lower than the glass transition temperature - 30°C of the polyester component having a lower glass transition temperature, the yarn unevenness increases too much, and, in addition, fluff or yarn breakage is likely to occur during spinning or false-twist texturing. Meanwhile, in the case where drawing is performed at a temperature higher than the glass transition temperature + 30°C of the polyester component having a higher glass transition temperature, the oriented crystallization of the conjugate fiber becomes too high, and even when draw false-twist texturing is subsequently performed, the crimp does not increase.

[0028] In addition to this, it is necessary that the polyester conjugate fiber after drawing is wound around a second heating roller at 30°C or more and 120°C or less. At this time, in the case where the fiber is wound up on a heating roller having a temperature of lower than 30°C, the oriented crystallization does not proceed, and when the fiber is stored at around room temperature, the fiber becomes brittle, making it difficult to handle the fiber or perform draw false-twist texturing. Meanwhile, in the case where the fiber is wound around a second heating roller having a temperature of higher than 120°C, the yarn elongates, and, due to yarn sway, yarn unevenness increases. In addition, the oriented crystallization of the obtained yarn is too high, and even when draw false-twist texturing is subsequently performed, the crimp does not increase.

[0029] Finally, the polyester conjugate fiber that has passed through the heating roller after drawing is wound up. In the case where the wind-up speed at this time is less than 2,000 m / min, the orientation of the fiber is low. Therefore, when the fiber is stored at around room temperature, the fiber becomes brittle, making it difficult to handle the fiber or perform draw false-twist texturing. Meanwhile, in the case where the wind-up speed exceeds 3300 m / min, the elongation becomes too low, and therefore, fluff or yarn breakage is likely to occur during spinning or false-twist texturing. In addition, also at the time of draw false-twist texturing, the crimp is reduced.

[0030] The polyester conjugate fiber obtained by the above method is preferable in that its crystallization has moderately proceeded, and therefore, tight winding due to the strain relaxation of the polymer is unlikely to occur, and changes over time are also small.(3) Yarn Physical Properties of Polyester Conjugate Fiber(a) Ratio of Crystallization Heat Quantity at Elevated Temperature

[0031] It is necessary that the ratio of crystallization heat quantity at elevated temperature of the polyester conjugate fiber measured by the below-described method is 10 to 60%, preferably 15% to 55%, relative to the completely amorphous state. In the case where the ratio of crystallization heat quantity at elevated temperature is more than 60% relative to the completely amorphous state, tight winding or the like occurs during winding up the conjugate fiber. In addition, in the case where the ratio of crystallization heat quantity at elevated temperature is less than 10%, the crystallinity becomes too high, and no crimp is developed even when draw false-twist texturing is performed.(b) Elongation at Break

[0032] It is necessary that the elongation at break of the polyester conjugate fiber is 60 to 200%. When the elongation at break is less than 60%, the elongation is too low, and thus fluff or yarn breakage is likely to occur during spinning or false-twist texturing. Meanwhile, in the case where the elongation at break is more than 200%, the degree of orientation of the fiber is too low. Accordingly, the fiber is susceptible to changes over time, and becomes extremely brittle even when stored at room temperature. As a result, it becomes impossible to stably obtain false twisted textured yarns of consistent quality on an industrial scale. The elongation at break is preferably within a range of 70 to 180%, and more preferably within a range of 75 to 150%.(c) Silk Factor (Breaking Strength × Elongation 1 / 2< )

[0033] It is necessary that the silk factor (strength × √elongation), which indicates the toughness of a yarn, of the polyester conjugate fiber is 10 or more. It is preferable that the silk factor is still more preferably 13 or more, and yet more preferably 15 or more. In the case where the silk factor is less than 10, yarn breakage occurs during drawing and false-twisting.(d) Thermal Stress

[0034] It is necessary that the peak temperature of the thermal stress of the polyester conjugate fiber is equal to or lower than the Tg + 50°C of the polyester component having a higher glass transition temperature (Tg) among the polyester components constituting the conjugate fiber. In the case where the peak temperature is higher than the Tg + 50°C of the polyester component having a higher glass transition temperature (Tg) among the polyester components constituting the conjugate fiber, the crystallinity becomes too high, and even when the fiber is formed into a false twisted textured yarn, no crimp is developed, and soft stretchability cannot be obtained.

[0035] In addition, it is necessary that the peak value of the thermal stress is 0.05 and 0.8 cN / dtex. The peak value of the thermal stress is still more preferably 0.06 to 0.7 cN / dtex, and the peak value of the thermal stress is most preferably 0.07 to 0.6 cN / dtex. When the peak value of the thermal stress is less than 0.05 cN / dtex, the tension during false-twist texturing decreases, and the crimp is reduced. Meanwhile, in the case where the peak value of the thermal stress is more than 0.8 cN / dtex, the tension during false-twist texturing becomes too high, causing yarn breakage or loss of softness.(4) False-Twist Texturing

[0036] A false twisted textured yarn made of the polyester conjugate fiber of the invention, which has a small initial modulus and also has high crimping performance even before a boiling water treatment, in which the difference in crimping characteristics before and after the boiling water treatment is small, can be obtained by subjecting a partially oriented yarn of the polyester conjugate fiber to draw false-twist texturing.

[0037] In the invention, by false-twist texturing the above polyester conjugate fiber under the following conditions, for example, the intended polyester false twisted textured yarn can be obtained.- False-Twisting Conditions

[0038] Type of false-twisting machine: HTS-15V manufactured by TMT Machinery, Inc. (disk false-twisting method) Disk rotation speed: 1,000 to 20,000 rpm (disk diameter: 3 to 10 cm) Feed speed: 500 to 1,000 m / min First feed rate: -5.0 to +5.0% First heater temperature (non-contact type): 200 to 300°C Second heater temperature (non-contact type): 150 to 250°C Second feed nip roller speed: 600 to 1,500 m / min Second feed rate: -5.0 to +5.0% Feed rate before winding up: -5.0 to +5.0%

[0039] The polyester false twisted textured yarn obtained by the above method is a false twisted textured yarn having high crimping performance even before a boiling water treatment, in which the difference in crimping characteristics before and after the boiling water treatment is small. Therefore, in the case where this yarn is used to make a fabric, the resulting fabric is soft and highly elastic, and the fabric exhibits moderate stretch. In addition, the fabric can be dyed using usual polyester disperse dyes. A fabric using the polyester conjugate fiber or polyester false twisted textured yarn of the invention eliminates the feeling of tightness when bending the elbows or knees or stretching the arms, allowing for use as a core yarn for clothing materials with high wearing comfort. Therefore, extreme usefulness is provided for outerwear, linings, sports, and like applications.

[0040] Incidentally, the total fineness of the polyester false twisted textured yarn obtained by the above method is preferably 10 to 200 dtex, and the tensile breaking strength is preferably 2.0 cN / dtex or more.(5) Yarn Physical Properties of Polyester False Twisted Textured Yarn(1) Modulus at 2% elongation is 10 cN / dtex or less

[0041] It is necessary that the modulus of the polyester false twisted textured yarn at 2% elongation is 10 cN / dtex or less. Here, a lower value of the modulus at 2% elongation indicates that higher crimp has occurred even before a boiling water treatment, and higher stretchability can be obtained. The modulus at 2% elongation is more preferably 8 cN / dtex or less. In the case where the modulus at 2% elongation is more than 10 cN / dtex, the occurrence of crimp before a boiling water treatment is small, and stretchability cannot be obtained.(2) Vc

[0042] Next, it is necessary that the apparent crimp degree (hereinafter abbreviated as Vc) of the polyester false twisted textured yarn measured by the following method is 10% ≤ Vc ≤ 50% (10 to 50%).(Vc Measurement Conditions)

[0043] A polyester false twisted textured yarn was wound up on a skein frame under a tension of 0.044 cN / dtex to prepare a skein having a thickness of about 3,300 dtex. Two loads, 0.00177 cN / dtex and 0.177 cN / dtex, were applied to one end of this skein, and the length S0 (cm) after an elapse of 1 minute was measured. Subsequently, a load of 0.00177 cN / dtex alone was applied to one end of the skein, and the length S1 (cm) after an elapse of 1 minute was measured. Vc was calculated by the following formula, and the average of 10 measured values was calculated. Vc = S 0 − S 1 / S 0 × 100

[0044] In the case where Vc is less than 10%, the occurrence of crimp before the boiling water treatment is small, and stretchability cannot be obtained. In addition, a Vc exceeding 50% leads to increased expansion and contraction, making handling difficult.(3) Tc

[0045] In addition, it is necessary that the latent crimp degree (hereinafter abbreviated as Tc) of the polyester false twisted textured yarn measured by the following method is 30% ≤ Tc ≤ 70% (30 to 70%).(Tc Measurement Conditions)

[0046] A polyester false twisted textured yarn sample was wound up on a skein frame under a tension of 0.044 cN / dtex to prepare a skein having a thickness of about 3,300 dtex. Two loads, 0.00177 cN / dtex and 0.177 cN / dtex, were applied to one end of this skein, and the length S2 (cm) after an elapse of 1 minute was measured. Next, the load of 0.177 cN / dtex was removed from the skein, and, in this state, the skein was treated in boiling water at 100°C for 20 minutes. After the boiling water treatment, the load of 0.00177 cN / dtex was removed from the skein, followed by natural drying in a free state under no load for 24 hours. Loads of 0.00177 cN / dtex and 0.177 cN / dtex were applied to the skein again, and the length S3 (cm) after an elapse of 1 minute was measured. Next, the load of 0.177 cN / dtex was removed from the skein, and the length S4 after an elapse of 1 minute was measured. Tc was calculated by the following formula, and the average of 10 measured values was calculated. Tc = S 2 − S 4 / S 2 × 100

[0047] In the case where Tc is less than 30%, the crimp is weakened by the boiling water treatment, and stretchability cannot be obtained. In addition, a Tc exceeding 70% leads to increased expansion and contraction, making handling difficult.(4) Vc - Tc

[0048] In addition, it is necessary that the above Vc and Tc of the polyester false twisted textured yarn have the relationship of the following calculation formula. − 20 % ≤ Vc − Tc ≤ 20 %

[0049] When Vc - Tc is less than -20%, the occurrence of crimp due to the boiling water treatment increases, and the yarn undergoes shrinkage due to the occurrence of crimp, resulting in a stiff texture when made into a fabric. In addition, when Vc - Tc is more than 20%, the weakening of the crimp caused by the boiling water treatment increases, resulting in loss of the stretchability of the yarn.

[0050] In the invention, when a polyester fiber structure is formed using the polyester conjugate fiber and the polyester false twisted textured yarn in an amount of 5 mass% or more, a fiber structure fabric that is soft and highly elastic, and exhibits moderate stretch, can be obtained.

[0051] As a specific example of the fiber structure, there is a woven or knitted fabric in which the above polyester conjugate fiber and a polyethylene terephthalate high-multifilament yarn having a single filament of 1 dtex or less are commingled, and then the commingled yarn is false-twist textured and thus formed into a yarn having high stretchability. When each component from the polyester conjugate fiber and the polyethylene terephthalate high-multifilament yarn having a single filament of 1 dtex or less is formed into a layer, and the surface layer is made of the polyethylene terephthalate high-multifilament yarn having a single filament of 1 dtex or less, while the central part forming the structure is made of the polyester conjugate fiber, the woven or knitted fabric having high stretchability, and whose surface has a soft texture derived from the high-multifilament yarn, can be achieved.Examples

[0052] Hereinafter, examples of the invention and comparative examples will be described in detail, but the invention is not limited thereto. Incidentally, measurement items in the Examples were measured by the following methods.(I) Intrinsic Viscosity [η]

[0053] The intrinsic viscosity [η] was determined using an Ostwald viscometer by extrapolating the ratio ηsp / C between the specific viscosity ηsp in o-chlorophenol at 35°C and the concentration C (g / 100 ml) to zero concentration according to the following formula. η = lim ηsp / C C → 0(II) Glass Transition Temperature [Tg]

[0054] Using a differential scanning calorimeter (DSC "Q-20") manufactured by TA Instruments, with a sample amount of 10 mg, the temperature was raised from room temperature to 350°C at a temperature rise rate of 10°C / min to completely melt each of the fiber raw material resins, followed by rapid cooling, and the temperature was further raised to 300°C at a rate of 10°C / min. From the temperature rise curve obtained at this time, the glass transition temperature (Tg) was measured.(III) Fineness

[0055] The fineness of a polyester conjugate fiber and that of a polyester false twisted textured yarn were measured in accordance with JIS-L-1013. In addition, the value was divided by the number of single yarns to determine the single yarn fineness.(IV) Breaking Strength, Elongation at Break, Silk Factor

[0056] Based on JIS-L-1013, using a constant-rate elongation type tensile tester TENSILON manufactured by Orientec Co., Ltd., the breaking strength and elongation at break were measured at a grip interval of 20 cm and a tensile rate of 20 cm / min. In addition, from the measured breaking strength and elongation at break, the silk factor was calculated using the following formula. (V) Ratio of Crystallization Heat Quantity at Elevated Temperature Relative to Completely Amorphous State

[0057] Using a differential scanning calorimeter (DSC "Q-20") manufactured by TA Instruments, the temperature was raised from 30°C to 10°C / min, and the crystallization exothermic peak derived from the conjugate fiber at elevated temperature at this time was measured, and defined as the elevated-temperature crystallization heat quantity = Q1.

[0058] Further, the temperature was raised to the melting point + 50°C of the resin constituting the fiber to completely melt the fiber, followed by rapid cooling with water, creating a completely amorphous state. The temperature was raised again from 30°C at 10°C / min, and the crystallization exothermic peak derived from the completely amorphous state at elevated temperature at this time was measured, and defined as the elevated-temperature crystallization heat quantity = Q2. From the following calculation formula, the ratio of crystallization heat quantity at elevated temperature relative to the completely amorphous state was determined.

[0059] Ratio of crystallization heat quantity at elevated temperature relative to the completely amorphous state = Q1 / Q2(VI) Thermal Stress and Peak Temperature of Polyester Composite Yarn

[0060] Using KE-2 manufactured by Kanebo Engineering Co., Ltd., measurement was performed with an initial load of 0.044 cN / dtex at a temperature rise rate of 100°C / min. The obtained data were plotted with temperature on the horizontal axis and thermal stress (thermal shrinkage stress) on the vertical axis to draw a temperature-thermal stress curve. The temperature and thermal stress (thermal shrinkage stress) at the point where the differential coefficient of the temperature-thermal stress curve changed from positive to negative were determined, and the stress was divided by fineness to determine the maximum stress.(VII) Modulus of False Twisted Textured Yarn

[0061] Based on JIS-L-1013, using a constant-rate elongation type tensile tester TENSILON manufactured by Orientec Co., Ltd., a tensile test was performed at a grip interval of 20 cm and a tensile rate of 20 cm / min, and a load-elongation curve was prepared. Subsequently, the modulus was determined from the tangent line at 2% elongation on the load-elongation curve.(VIII) Apparent Crimp Degree (Vc)

[0062] A polyester false twisted textured yarn was wound up on a skein frame under a tension of 0.044 cN / dtex to prepare a skein having a thickness of about 3,300 dtex. Two loads, 0.00177 cN / dtex and 0.177 cN / dtex, were applied to one end of this skein, and the length S0 (cm) after an elapse of 1 minute was measured. Subsequently, a load of 0.00177 cN / dtex alone was applied to one end of the skein, and the length S1 (cm) after an elapse of 1 minute was measured. Vc was calculated by the following calculation formula, and the average of 10 measured values was calculated. Vc = S 0 − S 1 / S 0 × 100(IX) Latent Crimp Degree (Tc)

[0063] A polyester false twisted textured yarn was wound up on a skein frame under a tension of 0.044 cN / dtex to prepare a skein having a thickness of about 3,300 dtex. Two loads, 0.00177 cN / dtex and 0.177 cN / dtex, were applied to one end of this skein, and the length S2 (cm) after an elapse of 1 minute was measured. Next, the load of 0.177 cN / dtex was removed from the skein, and, in this state, the skein was treated in boiling water at 100°C for 20 minutes. After the boiling water treatment, the load of 0.00177 cN / dtex was removed from the skein, followed by natural drying in a free state under no load for 24 hours. Loads of 0.00177 cN / dtex and 0.177 cN / dtex were applied to the skein again, and the length S3 (cm) after an elapse of 1 minute was measured. Next, the load of 0.177 cN / dtex was removed from the skein, and the length S4 after an elapse of 1 minute was measured. Tc was calculated by the following formula, and the average of 10 measured values was calculated. Tc = S 2 − S 4 / S 2 × 100[Example 1]

[0064] Dimethyl terephthalate and 1,3-propanediol were charged in a molar ratio of 1:2, then titanium tetrabutoxide equivalent to 0.1 wt% of dimethyl terephthalate was added, and a transesterification reaction was completed at a heater temperature of 240°C under normal pressure. Next, titanium tetrabutoxide was further added in 0.1 wt% of the theoretical polymer amount, and titanium dioxide was added in 0.5 wt% of the theoretical polymer amount, followed by a reaction at 270°C for 3 hours. The obtained polytrimethylene terephthalate had an intrinsic viscosity of 1.0 dl / g. The glass transition temperature of this polymer was 45°C.

[0065] In addition, this polymer was subjected to solid-phase polymerization at 180°C under nitrogen for 45 hours to obtain polytrimethylene terephthalate having an intrinsic viscosity of 1.4 dl / g. The glass transition temperature of this polymer was 46°C.

[0066] Using the polytrimethylene terephthalate having an intrinsic viscosity of 1.0 dl / g and polytrimethylene terephthalate having an intrinsic viscosity of 1.4 dl / g obtained above, they were each dried in a hot air dryer at 150°C for 6 hours to a moisture content of 50 ppm, then each melted at 265°C, and, using a spinneret having a side-by-side type cross-section, each extruded from a spinneret heated at 265°C in a mass ratio of 50:50 through discharge holes arranged in a single row provided with 24 0.3-mm-diameter discharge holes at a discharge rate of 14 g / min (total discharge amount).

[0067] The extruded molten multifilament was rapidly cooled by exposure to wind at a wind velocity of 2.0 m / min and thus converted into a solid multifilament. Subsequently, using a guide nozzle, an oil agent containing 60 wt% of octyl stearate, 15 wt% of a polyoxyethylene alkyl ether, and 3 wt% of potassium phosphate prepared as a water emulsion finishing agent with a concentration of 10 mass% was attached such that the amount of oil agent attached was 0.6 wt% relative to the fiber.

[0068] Next, the obtained solid multifilament was wound around a first heating roller heated to 50°C and having a peripheral speed of 2,200 m / min, then wound around a second heating roller at 80°C so as to be drawn to 1.2 times the original length, and subsequently wound up at a wind-up speed of 2,550 m / min (overfeed rate: 4%) using a wind-up machine configured to drive both the spindle and the touch roll, thereby giving a cheese package wound with a 56 dtex / 24 f polyester conjugate fiber. The physical properties of the obtained polyester conjugate fiber are shown in Table 1.

[0069] Next, using the obtained polyester conjugate fiber, draw false-twist texturing was performed at a draw ratio of 1.4 under the following conditions to produce a false twisted textured yarn. The physical properties of the obtained yarn are shown in Table 2.- False-Twisting Conditions

[0070] Type of false-twisting machine: HTS-15V manufactured by TMT Machinery, Inc. (disk false-twisting method) Disk rotation speed: 8,900 rpm (disc diameter: 5.8 cm) Feed speed: 430 m / min First feed rate: ±0% First heater temperature (non-contact type): 180°C Second heater temperature (non-contact type): 200°C Second feed nip roller speed: 600 m / min Second feed rate: 1.0% Feed rate before winding up: 4.0% [Example 2]

[0071] Using polytrimethylene terephthalate having an intrinsic viscosity of 1.0 dl / g and a glass transition temperature of 45°C and polyethylene terephthalate having an intrinsic viscosity of 0.6 dl / g and a glass transition temperature of 75°C, they were melted at 265°C and 285°C, respectively, and each extruded from a spinneret heated at 285°C in a ratio of 50:50 through a spinneret provided with 24 0.3-mm-diameter holes arranged in a single row at a discharge rate of 19 g / min (total discharge amount). The extruded molten multifilament was rapidly cooled by exposure to wind at a wind velocity of 2.0 m / min and thus converted into a solid multifilament. Subsequently, using a guide nozzle, an oil agent containing 60 wt% of octyl stearate, 15 wt% of a polyoxyethylene alkyl ether, and 3 wt% of potassium phosphate prepared as a water emulsion finishing agent with a concentration of 10 wt% was attached such that the amount of oil agent attached was 0.6 wt% relative to the fiber.

[0072] The fiber was then wound around a first heating roller heated to 50°C and having a peripheral speed of 1,300 m / min, drawn to 2.0 times the original length, wound around a second heating roller at 80°C, and subsequently wound up at a wind-up speed of 2,550 m / min (overfeed rate: 3%) using a wind-up machine configured to drive both the spindle and the touch roll, thereby giving a cheese package wound with a 75 dtex / 24 f polyester conjugate fiber. The physical properties of the obtained polyester conjugate fiber are shown in Table 1.

[0073] The fiber yarn physical properties of the obtained polyester conjugate fiber are shown in Table 1.

[0074] Subsequently, the obtained polyester conjugate fiber was subjected to draw false-twist texturing under the same conditions as in Example 1 except that the draw ratio was 1.6, thereby giving a polyester false twisted textured yarn. The physical properties of the obtained polyester false twisted textured yarn are shown in Table 2.[Comparative Example 1]

[0075] The trimethylene terephthalate having an intrinsic viscosity of 1.0 dl / g and a glass transition temperature of 45°C and trimethylene terephthalate having an intrinsic viscosity of 1.4 dl / g and a glass transition temperature of 46°C used in Example 1 were each separately melted, discharged in a composite ratio (mass%) of 50:50 from a 24-hole composite spinneret at a spinning temperature of 265°C, and then once wound up using a wind-up machine at a spinning speed of 1,400 m / min, thereby giving an undrawn yarn of a side-by-side type polyester conjugate fiber having 185 dtex / 24 filaments.

[0076] Further, using a hot roller-hot plate drawing machine (yarn contact length: 20 cm, surface roughness: 3S), the polyester conjugate fiber undrawn yarn was drawn at a hot roller temperature of 75°C, a hot plate temperature of 170°C, and a draw ratio of 2.2, and then, without being once taken up, continuously relax-treated to 0.9 times the original length and wound up, thereby giving a drawn yarn of a polyester conjugate fiber having 85 dtex / 24 filaments. The physical properties of the obtained polyester conjugate fiber are shown in Table 1.

[0077] Next, the obtained polyester conjugate fiber drawn yarn was false-twist textured under the following conditions. The physical properties of the obtained polyester false twisted textured yarn are shown in Table 2.- False-Twisting Conditions

[0078] Type of false-twisting machine: LS-2 manufactured by Mitsubishi Heavy Industries, Ltd. (pin false-twisting method) Yarn speed: 73 m / min (delivery roller 6) Twisting mechanism: Spindle type False-twisting direction: S Number of false twists: 3,810 T / m First heater temperature (contact type): 185°C Overfeed rate: 0% [Comparative Example 2]

[0079] The trimethylene terephthalate having an intrinsic viscosity of 1.40 dl / g and a glass transition temperature of 45°C and polyethylene terephthalate having an intrinsic viscosity of 0.60 dl / g and a glass transition temperature of 75°C used in Example 2 were each separately melted, discharged in a composite ratio (mass%) of 50:50 from a 24-hole composite spinneret at a spinning temperature of 275°C, and then once wound up using a wind-up machine at a spinning speed of 1,400 m / min, thereby giving an undrawn yarn of a side-by-side type polyester conjugate fiber having 185 dtex / 24 filaments.

[0080] Further, using a hot roller-hot plate drawing machine (yarn contact length: 20 cm, surface roughness: 3S), the polyester conjugate fiber undrawn yarn was drawn at a hot roller temperature of 75°C, a hot plate temperature of 170°C, and a draw ratio of 3.3, and then, without being once taken up, continuously relax-treated to 0.9 times the original length and wound up, thereby giving a drawn yarn of a polyester conjugate fiber having 56 dtex / 24 filaments. The physical properties of the obtained polyester conjugate fiber are shown in Table 1.

[0081] Next, the obtained polyester conjugate fiber drawn yarn was false-twist textured under the same conditions as in Comparative Example 1. The physical properties of the obtained polyester false twisted textured yarn are shown in Table 2.[Comparative Example 3]

[0082] Trimethylene terephthalate having an intrinsic viscosity of 1.0 dl / g and a glass transition temperature of 45°C and trimethylene terephthalate having an intrinsic viscosity of 1.4 dl / g and a glass transition temperature of 46°C were each separately melted, and, at a spinning temperature of 265°C, extruded from a 24-hole composite spinneret in a composite ratio (mass%) of 50:50 through a spinneret provided with 24 0.3-mm-diameter holes arranged in a single row at a discharge rate of 20 g / min (total discharge amount).

[0083] The extruded molten multifilament was rapidly cooled by exposure to wind at a wind velocity of 2.0 m / min and thus converted into a solid multifilament. Subsequently, using a guide nozzle, an oil agent containing 60 wt% of octyl stearate, 15 wt% of a polyoxyethylene alkyl ether, and 3 wt% of potassium phosphate prepared as a water emulsion finishing agent with a concentration of 10 wt% was attached such that the amount of oil agent attached was 0.6 wt% relative to the fiber.

[0084] Next, the obtained solid multifilament was wound around a first heating roller heated to 55°C and having a peripheral speed of 2,200 m / min, then wound around a second heating roller at 140°C so as to be drawn to 1.7 times the original length, and subsequently wound up at a wind-up speed of 3,510 m / min (overfeed rate: 6%) using a wind-up machine configured to drive both the spindle and the touch roll. The physical properties of the obtained polyester conjugate fiber are shown in Table 1.

[0085] Next, the obtained polyester conjugate fiber drawn yarn was false-twist textured at a draw ratio of 1.05 under the following conditions. The physical properties of the obtained polyester false twisted textured yarn are shown in Table 2.- False-Twisting Conditions

[0086] Type of false-twisting machine: LS-2 manufactured by Mitsubishi Heavy Industries, Ltd. (pin false-twisting method) Yarn speed: 73 m / min (delivery roller 6) False-twisting direction: S Number of false twists: 3,810 T / m Spindle rotation speed: 27,500 rpm First feed rate: ±0% First heater temperature (contact type): 160°C Second heater temperature (non-contact type): 150°C Overfeed rate: 5%. [Comparative Example 4]

[0087] In the same manner as in Example 2, using trimethylene terephthalate having an intrinsic viscosity of 1.0 dl / g and a glass transition temperature of 45°C and polyethylene terephthalate having an intrinsic viscosity of 0.60 dl / g and a glass transition temperature of 75°C, they were melted at 265°C and 285°C, respectively, and each extruded from a spinneret heated at 285°C in a ratio of 50:50 through a spinneret provided with 24 0.3-mm-diameter holes arranged in a single row at a discharge rate of 19 g / min (total discharge amount).

[0088] The extruded molten multifilament was rapidly cooled by exposure to wind at a wind velocity of 2.0 m / min and thus converted into a solid multifilament. Subsequently, using a guide nozzle, an oil agent containing 60 wt% of octyl stearate, 15 wt% of a polyoxyethylene alkyl ether, and 3 wt% of potassium phosphate prepared as a water emulsion finishing agent with a concentration of 10 wt% was attached such that the amount of oil agent attached was 0.6 wt% relative to the fiber.

[0089] Next, the obtained solid multifilament was wound around a first heating roller heated at 55°C and having a speed of 1,400 m / min, then wound around a heated second heating roller at 170°C so as to be drawn to 2.6 times the original length, and subsequently wound up at a wind-up speed of 3,430 m / min (overfeed rate: 6%) using a wind-up machine configured to drive both the spindle and the touch roll. The physical properties of the obtained polyester conjugate fiber are shown in Table 1.

[0090] Next, the obtained polyester conjugate fiber drawn yarn was false-twist textured under the same conditions as in Comparative Example 3. The physical properties of the obtained polyester false twisted textured yarn are shown in Table 2.[Comparative Example 5]

[0091] In the same manner as in Example 1, polytrimethylene terephthalate having an intrinsic viscosity of 1.0 dl / g and a glass transition temperature of 45°C and polytrimethylene terephthalate having an intrinsic viscosity of 1.4 dl / g and a glass transition temperature of 46°C were each separately melted, each melted at 265°C, and, using a spinneret having a side-by-side cross-section, each extruded from a spinneret heated at 265°C in a ratio of 50:50 through a spinneret provided with 24 0.3-mm-diameter holes arranged in a single row at a discharge rate of 19 g / min (total discharge amount).

[0092] The extruded molten multifilament was rapidly cooled by exposure to wind at a wind velocity of 2.0 m / min and thus converted into a solid multifilament. Subsequently, using a guide nozzle, an oil agent containing 60 wt% of octyl stearate, 15 wt% of a polyoxyethylene alkyl ether, and 3 wt% of potassium phosphate prepared as a water emulsion finishing agent with a concentration of 10 wt% was attached such that the amount of oil agent attached was 0.6 wt% relative to the fiber.

[0093] The obtained solid multifilament was wound around a first heating roller heated to 50°C and having a peripheral speed of 3,200 m / min, then wound around a second heating roller at 80°C so as to be drawn to 1.1 times the original length, and subsequently wound up at a wind-up speed of 3,360 m / min (overfeed rate: 6%) using a wind-up machine configured to drive both the spindle and the touch roll. The physical properties of the obtained polyester conjugate fiber are shown in Table 1.

[0094] Next, the obtained polyester conjugate fiber was subjected to draw false-twist texturing under the following conditions at a draw ratio of 1.1. The physical properties of the obtained polyester false twisted textured yarn are shown in Table 2. The amount of crimp in the obtained textured yarn was small.- False-Twisting Conditions

[0095] Type of false-twisting machine: HTS-15V manufactured by TMT Machinery, Inc. (disk false-twisting method) Disk rotation speed: 6,260 rpm (disc diameter: 5.8 cm) Feed speed: 530 m / min First feed rate: ±0% First heater temperature (non-contact type): 180°C Second heater temperature (non-contact type): 200°C Second feed nip roller speed: 600 m / min Second feed rate: 1.0% Feed rate before winding up: 4.0% [Comparative Example 6]

[0096] In the same manner as in Example 1, polytrimethylene terephthalate having an intrinsic viscosity of 1.0 dl / g and a glass transition temperature of 45°C and polytrimethylene terephthalate having an intrinsic viscosity of 1.4 dl / g and a glass transition temperature of 46°C were each separately melted, each melted at 265°C, and, using a spinneret having a side-by-side cross-section, each extruded from a spinneret heated at 265°C in a ratio of 50:50 through a spinneret provided with 24 0.3-mm-diameter holes arranged in a single row at a discharge rate of 15 g / min (total discharge amount).

[0097] The extruded molten multifilament was rapidly cooled by exposure to wind at a wind velocity of 2.0 m / min and thus converted into a solid multifilament. Subsequently, using a guide nozzle, an oil agent containing 60 wt% of octyl stearate, 15 wt% of a polyoxyethylene alkyl ether, and 3 wt% of potassium phosphate prepared as a water emulsion finishing agent with a concentration of 10 wt% was attached such that the amount of oil agent attached was 0.6 wt% relative to the fiber.

[0098] The obtained solid multifilament was wound around a non-heated first heating roller having a speed of 1,000 m / min, and then wound up at a speed of 1,000 m / min using a wind-up machine configured to drive both the spindle and the touch roll. The physical properties of the obtained polyester conjugate fiber are shown in Table 1.

[0099] Next, an attempt was made to subject the obtained polyester conjugate fiber to draw false-twist texturing under the same conditions as in Example 1. However, even when the draw ratio was changed, the yarn tension was low, yarn breakage occurred, and it was not possible to obtain a false twisted textured yarn.[Comparative Example 7]

[0100] In the same manner as in Example 1, polytrimethylene terephthalate having an intrinsic viscosity of 1.0 dl / g and a glass transition temperature of 45°C and polytrimethylene terephthalate having an intrinsic viscosity of 1.4 dl / g and a glass transition temperature of 46°C were each separately melted, each melted at 265°C, and, using a spinneret having a side-by-side cross-section, each extruded from a spinneret heated at 265°C in a ratio of 50:50 through a spinneret provided with 24 0.3-mm-diameter holes arranged in a single row at a discharge rate of 19 g / min (total discharge amount).

[0101] The extruded molten multifilament was rapidly cooled by exposure to wind at a wind velocity of 2.0 m / min and thus converted into a solid multifilament. Subsequently, using a guide nozzle, an oil agent containing 60 wt% of octyl stearate, 15 wt% of a polyoxyethylene alkyl ether, and 3 wt% of potassium phosphate prepared as a water emulsion finishing agent with a concentration of 10 wt% was attached such that the amount of oil agent attached was 0.6 wt% relative to the fiber.

[0102] The obtained solid multifilament was wound around a non-heated first heating roller having a speed of 2,600 m / min, then wound around a second heating roller having a speed of 2,600 m / min, and subsequently wound up at a wind-up speed of 2,600 m / min using a wind-up machine configured to drive both the spindle and the touch roll.

[0103] The obtained polyester conjugate fiber significantly deteriorated over time, and the winding state was poor, causing tight winding during winding up. Thus, it was not possible to stably collect yarn samples. The physical properties of the obtained polyester conjugate fiber, which was collected only in a small quantity, are shown in Table 1.

[0104] Next, an attempt was made to subject the obtained polyester conjugate fiber to draw false-twist texturing under the same conditions as in Example 1. However, even when the draw ratio was changed, the yarn tension was low, yarn breakage occurred, and it was not possible to obtain a false twisted textured yarn. [Table 1]Polymer 1Polymer 2Polyester Conjugate Fiber Physical PropertiesFirst ComponentLV dL / gTg °CSecond ComponentLV dL / gTg °CTotal Fineness dtexStrength cN / dtexElongation %Silk FactorRatio of Crystallization Heat Quantity at Elevated Temperature (%)Thermal Stress cN / dtexThermal Stress Peak Temperature °CExample 1PTT1.045PTT1.446561.99018200.1075Example 2PTT1.045PET0.675752.210022300.0875Comparative Example 1PTT1.045PTT1.446853.0301600.28176Comparative Example 2PTT1.045PET0.675563.3352000.24179Comparative Example 3PTT1.045PTT1.446573.0301600.28178Comparative Example 4PTT1.045PTT0.675563.3352000.23180Comparative Example 5PTT1.045PTT1.446562.5501850.2078Comparative Example 6PTT1.045PTT1.4461501.228020300.0260Comparative Example 7PTT1.045PTT1.446731.88517250.0373 [Table 2] Polyester False Twisted Textured Yarn Physical PropertiesTotal Fineness dtexStrength cN / dtexElongation (%)Modulus at 2% Elongation cN / dtexVc %Tc %Vc - Tc %Example 1412.44554245-3Example 2483.13583035-5Comparative Example 1853.025131547-32Comparative Example 2563.333151540-25Comparative Example 3553.025131547-32Comparative Example 4563.333151540-25Comparative Example 5552.63341028-18Comparative Example 6False twisted textured yarn not obtainedComparative Example 7False twisted textured yarn not obtained Industrial Applicability

[0105] According to the invention, a polyester conjugate fiber false twisted textured yarn having a small initial modulus and also having high crimping performance even before a boiling water treatment, in which the difference in crimping characteristics before and after the boiling water treatment is small, can be provided. When the yarn is used to make a fabric, a fabric having high crimping performance and thus having stretchability, which also has no difference crimping characteristics before and after a boiling water treatment, is resistant to yarn shrinkage even in subsequent steps such as dyeing, and has a soft texture, can be obtained.

Claims

1. A polyester conjugate fiber, being a conjugate fiber comprising polyester components having different intrinsic viscosities bonded together in a side-by-side manner, a bonded manner, or an eccentric sheath-core manner over the entire length of the fiber, wherein the conjugate fiber simultaneously satisfies the following requirements (a) to (d) : (a) the ratio of crystallization heat quantity at elevated temperature of the conjugate fiber is 10% to 60% relative to the completely amorphous state; (b) the elongation at break of the conjugate fiber is 60 to 200%; (c) the breaking strength (cN / dtex) × elongation1 / 2 (%) of the conjugate fiber ≥ 10; and (d) the peak temperature of the thermal stress of the conjugate fiber is equal to or lower than the glass transition temperature + 50°C of the polyester component having a higher glass transition temperature among the polyester components constituting the conjugate fiber, and the peak value of the thermal stress of the conjugate fiber is 0.05 to 0.8 cN / dtex.

2. The polyester conjugate fiber according to claim 1, wherein one of the polyester components constituting the conjugate fiber is a polyester containing 90 mol% or more of polytrimethylene terephthalate.

3. A method for producing a polyester conjugate fiber, wherein polyester components having different intrinsic viscosities are melt-discharged into the form of a conjugate fiber having the polyester components bonded together in a side-by-side manner, a bonded manner, or an eccentric sheath-core manner over the entire length of the fiber, then wound up at a wind-up speed of 1,000 to 3,000 m / min on a first heating roller at the glass transition temperature - 30°C of, among the polyester components, the polyester component having a lower glass transition temperature to the glass transition temperature + 30°C of the polyester component having a higher glass transition temperature, further drawn while being heated by the first heating roller, wound around a second heating roller at 30 to 120°C, and then wound up at a speed of 2,000 to 3,300 m / min.

4. A polyester false twisted textured yarn, being crimped and formed by false-twist texturing the polyester conjugate fiber according to claim 1, and simultaneously satisfying the following requirements (1) to (4): (1) the modulus at 2% elongation is 10 cN / dtex or less; (2) 10 % ≤ Vc ≤ 50 % ; (3) 30 % ≤ Tc ≤ 70 % ; and (4) − 20 % ≤ Vc − Tc ≤ 20 % .

5. The polyester false twisted textured yarn according to claim 4, wherein the false twisted textured yarn has a total fineness of 10 to 200 dtex and a tensile breaking strength of 2.0 cN / dtex or more.

6. A method for producing a polyester false twisted textured yarn, comprising drawing and false-twisting the polyester conjugate fiber according to claim 1.

7. A polyester fiber structure comprising the polyester conjugate fiber according to claim 1 and the polyester false twisted textured yarn according to claim 4 in an amount of 5 mass% or more.

Images