Polyester composite fiber, polyester false-twist processed yarn, and method for manufacturing polyester composite fiber and polyester false-twist processed yarn

Abstract

The purpose of the present invention is to provide: a polyester composite fiber which has a small initial elastic modulus, high crimp performance before boiling water treatment, and a small difference in crimp characteristics before and after boiling water treatment; a processed yarn; and a method for producing the polyester composite fiber. In the present invention, a polyester composite fiber, which is obtained by bonding polyesters having different intrinsic viscosities over the entire length of the fiber in a parallel type, a bonding type, or an eccentric core-sheath type, and which satisfies the following requirements (a) to (d) at the same time, is subjected to drawing and false twisting. (a) The crystallization heat ratio during temperature rise of the composite fiber is 10%-60% with respect to the completely amorphous state; (b) the elongation at break of the composite fiber is 60-200%; (c) the breaking strength (cN / dtex) * elongation 1 / 2 (%) of the composite fiber is greater than or equal to 10; (d) The peak temperature of the thermal stress of the composite fiber is 50 DEG C or less of the glass transition temperature of the polyester component having a higher glass transition temperature among the polyester components constituting the composite fiber, and the peak value of the thermal stress of the composite fiber is 0.05-0.8 cN / dtex.

Description

Technical Field

[0001] The present invention relates to a polyester conjugate fiber and a polyester false-twist yarn, and methods for producing the same. More specifically, the present invention relates to a partially oriented polyester conjugate fiber that stably provides low crystallinity and high elongation, and to a polyester conjugate fiber false-twist yarn obtained by stretching and false-twisting the polyester conjugate fiber, which has a low initial elastic modulus, high crimping performance before boiling water treatment, and a small difference in crimping characteristics before and after boiling water treatment, and methods for producing the same. Background Art

[0002] Polytrimethylene terephthalate (hereinafter sometimes referred to as "PTT"), obtained by polycondensing lower alcohol esters of terephthalic acid, represented by terephthalic acid or dimethyl terephthalate, with trimethylene glycol (1,3-propylene glycol), is a groundbreaking polymer that combines properties similar to polyamide, such as low elastic modulus (soft texture), excellent elastic recovery, and easy dyeing, with properties similar to polyethylene terephthalate (hereinafter sometimes referred to as "PET") fibers, such as light resistance, heat setting properties, dimensional stability, and low water absorption. Leveraging these characteristics, it has been applied to BCF carpets, brushes, tennis strings, and other products.

[0003] One fiber form that maximizes the aforementioned properties of PTT fibers is false twist yarn. This is because, as disclosed in Japanese Patent Application Laid-Open Nos. 11-093026, 2005-264424, and 2015-007306, false twist yarns made of PTT fibers exhibit greater elastic recovery and softness than fibers with a similar structure to PTT, such as polyester fibers like PET, making them excellent stretch yarns.

[0004] However, although false-twisted yarns obtained using PTT fibers as described above have excellent elastic recovery and softness, they are prone to yarn breakage, which prevents improved crimping performance. Consequently, it has been difficult to produce fine-denier, highly multifilament PTT false-twisted yarns with excellent crimping properties.

[0005] Meanwhile, parallel-type conjugate fibers containing various PTT components have been proposed. In particular, Japanese Patent Application Laid-Open No. 2005-264424 (Patent Document 1) discloses a parallel-type conjugate fiber or false-twisted yarn made from polytrimethylene terephthalate, which exhibits high crimp performance. However, this crimp is produced by a boiling water treatment, resulting in low crimp expression during fabric confinement or the crimp is easily deformed by external forces, thus failing to fully demonstrate its function as a stretchable fiber.

[0006] Furthermore, Japanese Patent Application Laid-Open No. 2003-301341 (Patent Document 2) discloses that a false-twisted yarn of a PTT composite fiber having excellent stretchability and high fabric quality is obtained by false-twisting and heat-setting a parallel or eccentric sheath-core composite fiber drawn yarn composed of two types of PTT having different inherent viscosities. However, due to the heat-setting, the crimp is reduced, and even in this case, the fiber does not have sufficient stretchability.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2005-264424

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2003-301341 Summary of the Invention

[0011] The present invention has been completed in view of the above background, and its purpose is to provide a polyester composite fiber and processed yarn having a small initial elastic modulus, high crimping performance before boiling water treatment, and a small difference in crimping characteristics before and after boiling water treatment, and a method for producing the same.

[0012] The present inventors have conducted intensive studies to achieve the above-mentioned object and have found that the above-mentioned problems can be solved by stretching and false twisting a partially oriented polyester conjugate fiber having low crystallinity and high elongation, thereby completing the present invention.

[0013] That is, the present invention can provide the following inventions:

[0014] 1. A polyester conjugate fiber characterized by being a conjugate fiber comprising polyesters having different intrinsic viscosities bonded together over the entire length of the fiber in a side-by-side, bonded, or eccentric core-sheath configuration, wherein the conjugate fiber simultaneously satisfies the following requirements (a) to (d);

[0015] (a) The crystallization heat ratio of the composite fiber when heated is 10% to 60% relative to the completely amorphous state.

[0016] (b) The breaking elongation of the composite fiber is 60-200%,

[0017] (c) Breaking strength of composite fiber (cN / dtex) × elongation 1 / 2 (%) ≥10,

[0018] (d) The peak temperature of the thermal stress of the conjugated fiber is not more than the glass transition temperature of the polyester component having a higher glass transition temperature among the polyester components constituting the conjugated fiber + 50° C., and the peak temperature of the thermal stress of the conjugated fiber is 0.05 to 0.8 cN / dtex.

[0019] 2. The polyester conjugate fiber according to item 1 above, wherein one component of the polyester constituting the conjugate fiber is a polyester containing 90 mol % or more of polytrimethylene terephthalate;

[0020] 3. A method for producing polyester conjugate fibers, characterized by melt-blowing polyesters having different intrinsic viscosities into a conjugate fiber formed by laminating the fibers in a parallel, laminated, or eccentric core-sheath configuration along the entire length of the fibers, then winding the fibers at a speed of 1000 to 3000 m / min using a first heated roller having a glass transition temperature between -30°C (-10°C) of the lower glass transition temperature polyester component and +30°C (10°C) of the higher glass transition temperature polyester component, further heating and stretching the fibers using the first heated roller, winding the fibers around a second heated roller at a temperature of 30 to 120°C, and then winding the fibers at a speed of 2000 to 3300 m / min.

[0021] 4. A polyester false twist yarn, characterized in that it has crimps formed by false twisting the polyester conjugate fiber described in 1 above, and satisfies the following requirements (1) to (4) at the same time;

[0022] (1) The elastic modulus at an elongation of 2% is less than 10 cN / dtex,

[0023] (2) 10%≤Vc≤50%,

[0024] (3) 30%≤Tc≤70%,

[0025] (4) -20%≤Vc-Tc≤20%.

[0026] 5. The polyester false-twist yarn according to 4 above, wherein the total fineness of the false-twist yarn is 10 to 200 dtex or less and the tensile strength at break is 2.0 cN / dtex or more;

[0027] 6. A method for producing a polyester false-twist yarn, characterized in that the polyester conjugate fiber described in 1 above is subjected to stretching and false twisting; and

[0028] 7. A polyester fiber structure comprising 5% by mass or more of the polyester conjugate fiber described in 1 above and the polyester false twist textured yarn described in 4 above.

[0029] According to the present invention, a partially oriented polyester conjugate fiber with low crystallinity and high elongation can be stably provided. By using the partially oriented polyester conjugate fiber for stretching and false twisting, a polyester false twist yarn with a small initial elastic modulus, high crimping performance before boiling water treatment, and a small difference in crimping characteristics before and after boiling water treatment can be provided, thereby obtaining a fiber structure with excellent stretchability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a cross-sectional view illustrating an example of the cross-sectional shape of the conjugate fiber of the present invention. DETAILED DESCRIPTION

[0031] Hereinafter, the present invention will be described in detail.

[0032] (1) Polymer raw materials

[0033] Preferred polymers for achieving the purpose of the present invention include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, polylactic acid, and thermoplastic polyester elastomers. The molecular weights of these polymers can be varied, such that a high molecular weight polymer is used as the first component and a low molecular weight polymer is used as the second component. Alternatively, polyesters having different intrinsic viscosities can be prepared by using a homopolymer as the first component and a copolymer as the second component.

[0034] In the present invention, it is preferred to use a polymer containing 90 mol% or more of polytrimethylene terephthalate as one of these components. In addition, it is further preferred to use the polytrimethylene terephthalate copolymer shown below because it has an excellent balance between curling characteristics and heat resistance. That is, within the range that does not impair the effects of the present invention, isophthalic acid, succinic acid, adipic acid, 2,6-naphthalene dicarboxylic acid, tetrabutyl 5-sulfoisophthalate, Acid components such as salt, diol components such as 1,4-butanediol, 1,6-hexanediol, and cyclohexanedimethanol, ε-caprolactone, 4-hydroxybenzoic acid, polyoxyethylene glycol, and polytetramethylene glycol are copolymerized in an amount of less than 10% by mass.

[0035] In addition, various additives such as matting agents, heat stabilizers, defoamers, color correcting agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents, fluorescent whitening agents, etc. may be copolymerized or mixed with the above polymers as needed.

[0036] When a poly(trimethylene terephthalate) polymer is used in the present invention, the intrinsic viscosity [η] is 0.5 to 1.6, preferably 0.6 to 1.5, and more preferably 0.7 to 1.4. An intrinsic viscosity of less than 0.5 may make it difficult to develop strength due to the excessively low molecular weight of the polymer. Conversely, an intrinsic viscosity exceeding 1.6 may impair the spinnability of the low-viscosity poly(trimethylene terephthalate) due to low fluidity, leading to yarn breakage during spinning, which is undesirable.

[0037] In the present invention, when a polytrimethylene terephthalate polymer is used as the first component, the polyester polymer used as the second component is preferably a polyester polymer such as polyethylene terephthalate, polybutylene terephthalate, low molecular weight or copolymerized polytrimethylene terephthalate, polytetramethylene terephthalate, or a polymer composed of copolymers thereof. Additives such as antistatic agents, flame retardants, heat-resistant agents, weathering agents, and titanium oxide may be added to these polymers or copolymers.

[0038] (2) Polyester composite fiber

[0039] The polyester composite fiber of the present invention needs to be arranged so that the polymers of the first component and the second component are closely attached to each other throughout the entire length of the fiber. The arrangement of the two components is not particularly limited and can be as follows Figure 1 Various fiber profiles such as parallel type, bonded type or eccentric core-sheath type are shown.

[0040] The polyester conjugate fiber of the present invention can be produced by a conventionally known conjugate spinning method that utilizes a spinning hole that can melt-blow polyesters having different intrinsic viscosities into a conjugate fiber-like shape that is bonded in a parallel, bonded, or eccentric core-sheath type over the entire length of the fiber. In addition, the two polyesters can be extruded in an equal volume ratio, or the ratio of each component can be appropriately changed. The ratio of the two components of the conjugate yarn is preferably in the range of 30 to 70 / 70 to 30. More preferably, it is 40 to 60 / 60 to 40. When the polytrimethylene terephthalate component is 70% or more, the crimping property is improved, but the strength of the conjugate fiber is sometimes reduced. On the other hand, when the polytrimethylene terephthalate component is less than 30%, the crimping property is sometimes insufficient.

[0041] The difference in melt viscosity between the first and second components is preferably 200 poise (measured at 290°C and a shear rate of 7780 cm⁻¹) or greater, and preferably 3000 poise or less. It is more preferably 250-2500 poise, and even more preferably 300-2000 poise. If the viscosity difference is less than 200 poise, crimping may not be observed. If it is greater than 3000 poise, when two components with different melt viscosities are composite-spun directly below the ejection hole, yarn bending may occur, whereby the yarn deviates toward the component with the higher melt viscosity, causing problems with workability.

[0042] If this yarn bending phenomenon occurs, not only does it deteriorate the yarn quality, but it also impairs spinnability and may even cause the yarn to stick to the spinneret, preventing production. Pre-processing the spinneret holes is one method of preventing yarn bending. However, as disclosed in British Patent No. 965729, for example, a method in which the spinneret holes are pre-curved in a direction opposite to the yarn bending direction and the polymer is ejected perpendicularly from the spinneret surface is also effective in producing the polyester conjugate fiber of the present invention.

[0043] The method for producing the polyester conjugate fiber will be described in further detail. To minimize moisture removal from the polyester sheet composed of the first and second components and inhibit hydrolysis, the sheet moisture content is reduced to 0.01% by mass or less using a sheet drying apparatus known in conventional polyester conjugate fiber production. The molten polymer is then extruded from a spinning spinneret perforated with nozzles corresponding to the target number of filaments through a melt extruder such as an extruder or silver plate melter. Cooling air is blown below the spinneret, and the sheet is drawn out with a guide roller while being cooled and solidified, and then wound onto a bobbin using a winder.

[0044] In addition, when obtaining a partially oriented yarn (POY) for producing a false twist textured yarn described later from the above-mentioned polyester conjugate fiber, the partially oriented yarn of the polyester conjugate fiber can be obtained by winding the polyester conjugate fiber using a first heated roller having a glass transition temperature (hereinafter sometimes referred to as Tg) of -30°C (the glass transition temperature of the polyester component having a lower glass transition temperature) to +30°C (the glass transition temperature of the polyester component having a higher glass transition temperature) at a winding speed of 1000 to 3000 m / min, further heating the polyester conjugate fiber using the first heated roller and stretching the polyester conjugate fiber 1.0 to 3.0 times, and then winding the polyester conjugate fiber using a second heated roller at a temperature of 30 to 120°C, and then winding the polyester conjugate fiber at a speed of 2000 to 3300 m / min.

[0045] When winding a polyester conjugate fiber containing polytrimethylene terephthalate that solidifies after melting, if the winding is performed at a speed lower than 1000 m / min, not only is the production efficiency poor, but the stretch ratio becomes too high, so that orientation crystallization proceeds excessively, and even if stretching and false twisting are performed subsequently, the crimping does not increase.

[0046] Furthermore, when the polyester conjugate fiber is wound at a speed faster than 3000 m / min, the elongation becomes too low, and thus fuzz and yarn breakage are easily generated during spinning and false twisting. Furthermore, crimping is also reduced during stretching and false twisting.

[0047] Furthermore, stretching at a temperature lower than -30°C (the glass transition temperature of the lower glass transition temperature polyester component) can lead to excessive yarn unevenness, and fuzz and yarn breakage can easily occur during spinning or false twisting. On the other hand, stretching at a temperature higher than +30°C (the glass transition temperature of the higher glass transition temperature polyester component) can lead to excessively high orientation and crystallization of the conjugate fiber, and crimping will not increase even after subsequent stretching and false twisting.

[0048] Furthermore, after stretching, the polyester conjugate fiber needs to be wound around a second heated roller at a temperature between 30°C and 120°C. Winding the yarn using a heated roller at a temperature below 30°C prevents proper orientation and crystallization. This makes the fiber brittle and difficult to handle, stretch, or false twist, if stored near room temperature. On the other hand, winding the yarn around a second heated roller at a temperature above 120°C causes the yarn to stretch, resulting in significant yarn unevenness due to yarn wobbling. Furthermore, the resulting yarn exhibits excessively high orientation and crystallization, and subsequent stretching and false twisting will result in insufficient crimping.

[0049] Finally, after stretching, the polyester conjugate fiber is wound after passing through heated rollers. However, if the winding speed is less than 2000 m / min, the fiber orientation is low. Consequently, if the fiber is stored near room temperature, it becomes brittle and difficult to handle or perform stretching and false twisting. On the other hand, if the winding speed exceeds 3300 m / min, the elongation becomes too low, making fuzz and yarn breakage more likely during spinning and false twisting. Furthermore, crimping is reduced during stretching and false twisting.

[0050] The polyester conjugate fiber obtained by the above method is preferably obtained because crystallization proceeds moderately, and therefore winding tightness due to polymer strain relaxation is less likely to occur and changes over time are also small.

[0051] (3) Yarn properties of polyester composite fibers

[0052] (a) Crystallization heat ratio during heating

[0053] The polyester conjugate fiber's heat of crystallization ratio, measured by the method described below, should be 10% to 60% of that of the completely amorphous fiber, preferably 15% to 55%. If the heat of crystallization ratio exceeds 60% of that of the completely amorphous fiber, winding may occur during winding of the conjugate fiber. If the heat of crystallization ratio is less than 10%, the crystallinity becomes too high, and crimping may not occur even during stretching and false twisting.

[0054] (b) Elongation at break

[0055] The elongation at break of polyester composite fibers needs to be 60% to 200%. If the elongation at break is less than 60%, fuzz and yarn breakage are likely to occur during spinning and false twisting due to the low elongation. On the other hand, if the elongation at break exceeds 200%, the fiber orientation is too low and easily changes over time. In addition, the fiber becomes very brittle even when stored at room temperature. Therefore, it is difficult to stably obtain false twisted yarn of consistent industrial quality. The preferred range of elongation at break is 70% to 180%, and the more preferred range is 75% to 150%.

[0056] (c) Yarn factor (breaking strength × elongation 1 / 2 )

[0057] The yarn factor (strength × ) needs to be 10 or more. It is preferably 13 or more, and even more preferably 15 or more. If the yarn factor is less than 10, yarn breakage occurs during stretching and false twisting.

[0058] (d) Thermal stress

[0059] The peak temperature of thermal stress in polyester conjugate fibers must be no higher than the Tg+50°C of the polyester component with the higher glass transition temperature (Tg) among the polyester components constituting the conjugate fibers. If this peak temperature is higher than the Tg+50°C of the polyester component with the higher glass transition temperature (Tg) among the polyester components constituting the conjugate fibers, the crystallinity becomes too high, and even when formed into false-twisted yarn, crimping will not occur, and soft stretchability cannot be achieved.

[0060] Furthermore, the peak thermal stress value should be between 0.05 and 0.8 cN / dtex. A more preferred peak thermal stress value is between 0.06 and 0.7 cN / dtex, and most preferably between 0.07 and 0.6 cN / dtex. If the peak thermal stress value is less than 0.05 cN / dtex, the tension during false twisting is reduced, resulting in less crimp. On the other hand, if the peak thermal stress value exceeds 0.8 cN / dtex, the tension during false twisting becomes excessive, causing yarn breakage and loss of softness.

[0061] (4) False twist processing

[0062] The false twisted yarn formed from the polyester conjugate fiber of the present invention having a small initial elastic modulus, high crimping performance before boiling water treatment, and a small difference in crimping characteristics before and after boiling water treatment can be obtained by stretching and false twisting the partially oriented yarn of the above polyester conjugate fiber.

[0063] In the present invention, the above-mentioned polyester conjugate fiber can be subjected to false twist processing under the following conditions, for example, to obtain the target polyester false twist textured yarn.

[0064] ・False twist conditions

[0065] False twist machine type: HTS-15V manufactured by TMT Machinery Co., Ltd. (disc false twist method)

[0066] Disc speed: 1000-20000rpm (disc diameter 3-10cm)

[0067] Feeding speed: 500~1000m / min

[0068] First feed rate: -5.0~+5.0%

[0069] 1st heater temperature (non-contact type): 200~300℃

[0070] Second heater temperature (non-contact type): 150-250°C

[0071] Second feed nip roller speed: 600~1500m / min

[0072] Second feed rate: -5.0~+5.0%

[0073] Feed rate before coiling: -5.0~+5.0%

[0074] The polyester false-twist yarn obtained by the above method exhibits high crimping properties before and after boiling water treatment, with a small difference in crimping properties before and after boiling water treatment. Therefore, when made into fabric, it produces a soft, highly stretchable fabric that exhibits moderate stretchability. Furthermore, it can be dyed using conventional polyester disperse dyes. Fabrics made from the polyester conjugate fiber and polyester false-twist yarn of the present invention can be made into core yarns for clothing materials that eliminate the feeling of tightness when bending the elbows or knees or extending the arms, providing excellent wear comfort. Therefore, it is extremely useful in outerwear, linings, and sportswear applications.

[0075] The polyester false twist textured yarn obtained by the above method preferably has a total fineness of 10 to 200 dtex or less, and a tensile strength at break of 2.0 cN / dtex or more.

[0076] (5) Yarn properties of polyester false twist yarn

[0077] (1) The elastic modulus at an elongation of 2% is less than 10 cN / dtex

[0078] The elastic modulus of polyester false-twist yarn at an elongation of 2% must be 10 cN / dtex or less. A lower elastic modulus at an elongation of 2% results in a higher crimping rate before boiling water treatment, which results in higher stretchability. The elastic modulus at an elongation of 2% is more preferably 8 cN / dtex or less. If the elastic modulus at an elongation of 2% exceeds 10 cN / dtex, the crimping rate before boiling water treatment is minimal, and stretchability cannot be achieved.

[0079] (2) Vc

[0080] Next, the apparent crimp percentage (hereinafter abbreviated as Vc) measured by the following method for the polyester false twist textured yarn needs to be within the range of 10%≤Vc≤50% (10 to 50%).

[0081] (Vc determination conditions)

[0082] Polyester false-twist textured yarn was wound on a spinning frame under a tension of 0.044 cN / dtex to produce a hank (skein) with a thickness of approximately 3300 dtex. Two loads, 0.00177 cN / dtex and 0.177 cN / dtex, were applied to one end of the hank, and the length S0 (cm) was measured after one minute. Then, a load of only 0.00177 cN / dtex was applied to one end of the hank, and the length S1 (cm) was measured after one minute. Vc was calculated using the following formula, and the average of 10 measured values ​​was calculated.

[0083] Vc=(S0-S1) / S0×100

[0084] When Vc is less than 10%, the curling before the boiling water treatment is small and the stretchability cannot be obtained. On the other hand, when Vc exceeds 50%, the stretchability becomes large and the handling becomes difficult.

[0085] (3) Tc

[0086] The potential crimp percentage (hereinafter abbreviated as Tc) of the polyester false twist textured yarn measured by the following method needs to be 30%≤Tc≤70% (30 to 70%).

[0087] (Tc measurement conditions)

[0088] A sample of polyester false-twist textured yarn was wound on a spinning frame under a tension of 0.044 cN / dtex to produce a skein (yield) with a thickness of approximately 3300 dtex. Two loads of 0.00177 cN / dtex and 0.177 cN / dtex were applied to one end of the skein, and the length S2 (cm) was measured after one minute. Next, with the 0.177 cN / dtex load removed from the skein, the yarn was immersed in boiling water at 100°C for 20 minutes. After the boiling water treatment, the 0.00177 cN / dtex load was removed from the skein, which was then naturally dried without a load for 24 hours. The skein was then subjected to loads of 0.00177 cN / dtex and 0.177 cN / dtex, and the length S3 (cm) was measured after one minute. Next, a load of 0.177 cN / dtex was removed from the hank, and the length S4 after 1 minute was measured. Tc was calculated using the following formula, and the average value of 10 measured values ​​was calculated.

[0089] Tc=(S2-S4) / S2×100

[0090] When Tc is less than 30%, the curling is deformed by the boiling water treatment, and thus the stretchability cannot be obtained. On the other hand, when Tc exceeds 70%, the stretching becomes large, and it becomes difficult to handle.

[0091] (4) Vc-Tc

[0092] Furthermore, the above-mentioned Vc and Tc of the polyester false twist textured yarn need to be in the relationship expressed by the following formula.

[0093] -20%≤Vc-Tc≤20%

[0094] If the Vc-Tc ratio is less than -20%, the crimping caused by the boiling water treatment becomes more pronounced, causing visible shrinkage of the yarn and resulting in a stiff texture when made into fabric. On the other hand, if the Vc-Tc ratio exceeds 20%, the crimping deformation caused by the boiling water treatment becomes more pronounced, resulting in a loss of yarn stretchability.

[0095] In the present invention, when the polyester fiber structure is formed using 5% by mass or more of the polyester conjugate fiber and the polyester false twist textured yarn, a fiber structure fabric that is soft, highly stretchable, and exhibits moderate stretchability can be obtained.

[0096] As a specific example of a fiber structure, the polyester composite fiber is blended with a polyethylene terephthalate high multifilament yarn having a single yarn size of less than 1 dtex, and the blended yarn is false-twisted to form a woven fabric having a highly stretchable yarn. The components derived from the polyester composite fiber and the polyethylene terephthalate high multifilament yarn having a single yarn size of less than 1 dtex are formed into layers, the surface layer is the polyethylene terephthalate high multifilament yarn having a single yarn size of less than 1 dtex, and the middle portion forming the structure is the polyester composite fiber. This allows for a woven fabric having high stretchability and a soft texture on the surface derived from the high multifilament yarn.

[0097] Example

[0098] Hereinafter, the examples and comparative examples of the present invention will be described in detail, but the present invention is not limited thereto. It should be noted that each measurement item in the examples was measured by the following method.

[0099] (1) Intrinsic viscosity [η]

[0100] The intrinsic viscosity [η] is determined by extrapolating the ratio ηsp / C of the specific viscosity ηsp in o-chlorophenol at 35°C to the concentration C (g / 100 ml) using an Ostwald viscometer to zero, using the following formula.

[0101] [η] = lim (ηsp / C)

[0102] C→0

[0103] (2) Glass transition temperature [Tg]

[0104] Using a differential scanning calorimeter (DSC "Q-20") manufactured by TA Instruments, a 10 mg sample was heated from room temperature to 350°C at a heating rate of 10°C / minute to completely melt the various resins that would become the raw materials for the fibers. The sample was then rapidly cooled and further heated to 300°C at a rate of 10°C / minute. The glass transition temperature (Tg) was determined based on the heating curve obtained at this time.

[0105] (3) Fineness

[0106] The fineness of the polyester conjugate fiber and the polyester false twist textured yarn was measured in accordance with JIS-L-1013. The single yarn fineness was determined by dividing the measured value by the number of single yarns.

[0107] (4) Breaking strength, breaking elongation, yarn factor

[0108] In accordance with JIS-L-1013, the breaking strength and elongation at break were measured using a Tensilon, a constant-rate tensile testing machine manufactured by Orientec Co., Ltd., at a grip spacing of 20 cm and a tensile speed of 20 cm / min. The yarn factor was calculated from the measured breaking strength and elongation using the following formula.

[0109] Yarn factor = breaking strength (cN / dtex) × breaking elongation 1 / 2 (%)

[0110] (5) Crystallization heat ratio when heating compared with completely amorphous

[0111] Using a differential scanning calorimeter (DSC "Q-20") manufactured by TA Instruments, the crystallization exothermic peak of the conjugate fiber during heating at 10°C / min from 30°C was measured and defined as the heating heat of crystallization = Q1.

[0112] The temperature was then raised to the melting point of the fiber-constituting resin + 50°C to completely melt the fiber, followed by rapid cooling with water to produce a completely amorphous state. The temperature was then raised again from 30°C at a rate of 10°C / minute. The crystallization exotherm peak from the completely amorphous state during the heating process was measured and defined as the heating heat of crystallization = Q2. The ratio of the heating heat of crystallization to the completely amorphous state was calculated using the following formula.

[0113] The ratio of heat of crystallization during heating compared to completely amorphous = Q1 / Q2

[0114] (6) Thermal stress and peak temperature of polyester composite yarn

[0115] Measurements were performed using a KE-2 manufactured by Kanebo Engineering with an initial load of 0.044 cN / dtex and a heating 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 create 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 changes from positive to negative were determined. The stress was then divided by the fineness to determine the maximum stress.

[0116] (7) Elastic modulus of false twist yarn

[0117] Tensile tests were conducted in accordance with JIS-L-1013 using a Tensilon (manufactured by Orientec Corporation), a constant-rate tensile testing machine, with a grip spacing of 20 cm and a tensile speed of 20 cm / min. A load-elongation curve was generated. The elastic modulus was then determined from the tangent line of the load-elongation curve at 2% elongation.

[0118] (8) Apparent curling rate (Vc)

[0119] Polyester false-twist textured yarn was wound on a spinning frame under a tension of 0.044 cN / dtex to produce a hank (skein) with a thickness of approximately 3300 dtex. Two loads, 0.00177 cN / dtex and 0.177 cN / dtex, were applied to one end of the hank, and the length S0 (cm) was measured after one minute. Then, a load of only 0.00177 cN / dtex was applied to one end of the hank, and the length S1 (cm) was measured after one minute. Vc was calculated using the following formula, and the average of 10 measured values ​​was calculated.

[0120] Vc=(S0-S1) / S0×100

[0121] (9) Potential shrinkage (Tc)

[0122] Polyester false-twist textured yarn was wound on a spinning frame under a tension of 0.044 cN / dtex to produce a skein (yield) with a thickness of approximately 3300 dtex. Two loads of 0.00177 cN / dtex and 0.177 cN / dtex were applied to one end of the skein, and the length S2 (cm) was measured after one minute. Next, with the 0.177 cN / dtex load removed, the skein was treated in boiling water at 100°C for 20 minutes. After the boiling water treatment, the 0.00177 cN / dtex load was removed from the skein, which was then naturally dried without a load for 24 hours. The skein was then subjected to loads of 0.00177 cN / dtex and 0.177 cN / dtex, and the length S3 (cm) was measured after one minute. Next, a load of 0.177 cN / dtex was removed from the hank, and the length S4 after 1 minute was measured. Tc was calculated using the following formula, and the average value of 10 measured values ​​was calculated.

[0123] Tc=(S2-S4) / S2×100

[0124] [Example 1]

[0125] Dimethyl terephthalate and 1,3-propylene glycol were added at a molar ratio of 1:2. Tetrabutoxytitanium (equivalent to 0.1% by weight of the dimethyl terephthalate) was added, and the transesterification reaction was completed at a heater temperature of 240°C under normal pressure. Subsequently, 0.1% by weight of tetrabutoxytitanium and 0.5% by weight of titanium dioxide were added, and the reaction was continued at 270°C for 3 hours. The resulting poly(trimethylene terephthalate) had an intrinsic viscosity of 1.0 dl / g and a glass transition temperature of 45°C.

[0126] Furthermore, 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.

[0127] The poly(trimethylene terephthalate) with an intrinsic viscosity of 1.0 dl / g and the poly(trimethylene terephthalate) with an intrinsic viscosity of 1.4 dl / g obtained above were dried in a hot air dryer at 150°C for 6 hours to reduce the moisture content to 50 ppm, and then melted at 265°C. The melts were extruded from a spinning spinneret heated at 265°C at a mass ratio of 50:50 and a total ejection rate of 14 g / min through a single array of 24 ejection holes with a diameter of 0.3 mm using a spinneret with a parallel cross-section.

[0128] After rapidly cooling the extruded molten multifilaments by blowing air at a speed of 2.0 m / min to form solid multifilaments, a water-emulsified finishing agent containing 60% by weight of octyl stearate, 15% by weight of polyoxyethylene alkyl ether, and 3% by weight of potassium phosphate at a concentration of 10% by weight was applied to the fibers using a guide nozzle so that the amount of the oil deposited was 0.6% by weight.

[0129] The resulting solid multifilament was then wound around a first heated roll heated to 50°C and running at a peripheral speed of 2200 m / min. It was then drawn 1.2 times around a second heated roll at 80°C. The resulting multifilament was then wound using a winder that used both a driven spindle and a touch roll at a winding speed of 2550 m / min (overfeed ratio of 4%) to produce a bobbin-shaped package containing 56 dtex / 24f polyester conjugate fibers. The physical properties of the resulting polyester conjugate fibers are shown in Table 1.

[0130] Next, the obtained polyester conjugate fiber was subjected to a stretching false twisting process at a stretching ratio of 1.4 times under the following conditions to produce a false twisted yarn.

[0131] ・False twist conditions

[0132] False twist machine type: HTS-15V manufactured by TMT Machinery Co., Ltd. (disc false twist method)

[0133] Disc speed: 8900 rpm (disc diameter 5.8 cm)

[0134] Feed speed: 430m / min

[0135] First feed rate: ±0%

[0136] 1st heater temperature (non-contact type): 180°C

[0137] Second heater temperature (non-contact type): 200°C

[0138] Second feed nip roller speed: 600m / min

[0139] Second feed rate: 1.0%

[0140] Feed rate before coiling: 4.0%

[0141] [Example 2]

[0142] Poly(trimethylene terephthalate) with an intrinsic viscosity of 1.0 dl / g and a glass transition temperature of 45°C and polyethylene terephthalate with an intrinsic viscosity of 0.6 dl / g and a glass transition temperature of 75°C were melted at 265°C and 285°C, respectively. The fibers were extruded from a spinning spinneret heated at 285°C at a 50:50 ratio, with a total discharge rate of 19 g / min, through a single-array spinning nozzle containing 24 holes with a diameter of 0.3 mm. The extruded molten multifilaments were rapidly cooled by air at a speed of 2.0 m / min to form solid multifilaments. A 10% by weight aqueous emulsion finish containing 60% by weight of octyl stearate, 15% by weight of polyoxyethylene alkyl ether, and 3% by weight of potassium phosphate was then applied to the fibers using a guide nozzle to achieve an oiling agent deposition rate of 0.6% by weight.

[0143] The fiber was then wound around a first heated roll heated to 50°C and running at a peripheral speed of 1300 m / min, stretched at 2.0 times, and wound around a second heated roll at 80°C. The fiber was then taken up at a winding speed of 2550 m / min (overfeed ratio 3%) using a winder that used both a driven spindle and a touch roll, yielding a bobbin-shaped package containing 75 dtex / 24f polyester conjugate fibers. The physical properties of the resulting polyester conjugate fibers are shown in Table 1.

[0144] Table 1 shows the fiber yarn physical properties of the obtained polyester conjugate fiber.

[0145] The obtained polyester conjugate fiber was then subjected to stretching and false twisting under the same conditions as in Example 1 except that the stretching ratio was 1.6 times to obtain a polyester false twist yarn. The physical properties of the obtained polyester false twist yarn are shown in Table 2.

[0146] [Comparative Example 1]

[0147] The trimethylene terephthalate with an intrinsic viscosity of 1.0 dl / g and a glass transition temperature of 45°C and the trimethylene terephthalate with an intrinsic viscosity of 1.4 dl / g and a glass transition temperature of 46°C used in Example 1 were melted and discharged from a 24-hole conjugate spinning spinneret at a conjugate ratio (mass %) of 50:50 at a spinning temperature of 265°C. The yarns were temporarily wound up using a winder at a spinning speed of 1400 m / min to obtain undrawn yarns of 185 dtex, 24-filament side-by-side polyester conjugate fibers.

[0148] The undrawn polyester conjugate fiber yarn was then stretched using a hot roller and hot plate stretching machine (spinning length: 20 cm, surface roughness: 3S) at a hot roller temperature of 75°C, a hot plate temperature of 170°C, and a draw ratio of 2.2. The yarn was then continuously relaxed at a draw ratio of 0.9 without drawing the yarn back, and wound up to produce a drawn polyester conjugate fiber yarn of 85 dtex and 24 filaments. The physical properties of the resulting polyester conjugate fiber are shown in Table 1.

[0149] The physical properties of the obtained polyester false-twisted yarn are shown in Table 2.

[0150] ・False twist conditions

[0151] False twist machine type: Mitsubishi Heavy Industries LS-2 (needle false twist method)

[0152] Yarn speed: 73m / min (conveying roller 6)

[0153] Twisting body: spindle type

[0154] False twist direction: S

[0155] False twist number: 3810T / m

[0156] 1st heater temperature (contact type): 185℃

[0157] Overfeeding rate: 0%

[0158] [Comparative Example 2]

[0159] The trimethylene terephthalate with an intrinsic viscosity of 1.40 dl / g and a glass transition temperature of 45°C and the polyethylene terephthalate with an intrinsic viscosity of 0.60 dl / g and a glass transition temperature of 75°C used in Example 2 were melted separately, ejected from a 24-hole conjugate spinning spinneret at a conjugate ratio (mass %) of 50:50 at a spinning temperature of 275°C, and temporarily wound up using a winder at a spinning speed of 1400 m / min to obtain an undrawn yarn of a 185 dtex, 24-filament side-by-side polyester conjugate fiber.

[0160] The undrawn polyester conjugate fiber yarn was then stretched using a hot roller and hot plate stretching machine (spinning length: 20 cm, surface roughness: 3S) at a hot roller temperature of 75°C, a hot plate temperature of 170°C, and a draw ratio of 3.3. The yarn was then continuously relaxed at a draw ratio of 0.9 without drawing the yarn back, and wound up to produce a 56 dtex, 24-filament drawn polyester conjugate fiber yarn. The physical properties of the resulting polyester conjugate fiber are shown in Table 1.

[0161] Next, the drawn polyester conjugate fiber yarn obtained was false-twisted under the same conditions as in Comparative Example 1. The physical properties of the obtained polyester false-twisted yarn are shown in Table 2.

[0162] [Comparative Example 3]

[0163] Tripropylene 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 melted and extruded from a 24-hole conjugate spinning spinneret at a spinning temperature of 265°C at a conjugate ratio (mass %) of 50:50 and a total discharge rate of 20 g / min through a single-array spinning nozzle having 24 holes with a diameter of 0.3 mm.

[0164] After rapidly cooling the extruded molten multifilaments by blowing air at a speed of 2.0 m / min to form solid multifilaments, a water-emulsified finishing agent containing 60% by weight of octyl stearate, 15% by weight of polyoxyethylene alkyl ether, and 3% by weight of potassium phosphate was applied to the fibers using a guide nozzle to a 10% by weight concentration of the water-emulsified finishing agent so that the amount of the oil deposited was 0.6% by weight.

[0165] The resulting solid multifilament was then wound around a first heated roll heated to 55°C and running at a peripheral speed of 2200 m / min. It was then drawn 1.7 times around a second heated roll at 140°C. The resulting fiber was then wound using a winder that used both a driven spindle and a touch roller at a winding speed of 3510 m / min (overfeed ratio of 6%). The physical properties of the resulting polyester conjugate fiber are shown in Table 1.

[0166] The drawn polyester conjugate fiber yarn thus obtained was false-twisted at a draw ratio of 1.05 times under the following conditions.

[0167] ・False twist conditions

[0168] False twist machine type: Mitsubishi Heavy Industries LS-2 (needle false twist method)

[0169] Yarn speed: 73m / min (conveying roller 6)

[0170] False twist direction: S

[0171] False twist number: 3810T / m

[0172] Spindle speed: 27500rpm

[0173] First feed rate: ±0%

[0174] 1st heater temperature (contact type): 160℃

[0175] Second heater temperature (non-contact type): 150°C

[0176] Overfeed rate: 5%.

[0177] [Comparative Example 4]

[0178] In the same manner as in Example 2, 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 were used. These were melted at 265°C and 285°C, respectively, and extruded from a spinning spinneret heated at 285°C at a ratio of 50:50 and a total discharge rate of 19 g / min through a single-array spinneret having 24 holes with a diameter of 0.3 mm.

[0179] After rapidly cooling the extruded molten multifilaments by blowing air at a speed of 2.0 m / min to form solid multifilaments, a water-emulsified finishing agent containing 60% by weight of octyl stearate, 15% by weight of polyoxyethylene alkyl ether, and 3% by weight of potassium phosphate was applied to the fibers using a guide nozzle to a 10% by weight concentration of the water-emulsified finishing agent so that the amount of the oil deposited was 0.6% by weight.

[0180] The resulting solid multifilament was then wound around a first heated roll heated at 55°C at a speed of 1400 m / min. It was then stretched 2.6 times around a second heated roll heated at 170°C. The resulting fiber was then wound at a speed of 3430 m / min (overfeed ratio 6%) using a winder that used both a driven spindle and a touch roll. The physical properties of the resulting polyester conjugate fiber are shown in Table 1.

[0181] Next, the drawn polyester conjugate fiber yarn obtained was false-twisted under the same conditions as in Comparative Example 3. The physical properties of the obtained polyester false-twisted yarn are shown in Table 2.

[0182] [Comparative Example 5]

[0183] As in Example 1, poly(trimethylene terephthalate) having an intrinsic viscosity of 1.0 dl / g and a glass transition temperature of 45°C and poly(trimethylene terephthalate) having an intrinsic viscosity of 1.4 dl / g and a glass transition temperature of 46°C were melted separately at 265°C and extruded from a spinning nozzle heated at 265°C at a ratio of 50:50 and a total discharge rate of 19 g / min through a single-array spinning nozzle having 24 holes with a diameter of 0.3 mm.

[0184] After rapidly cooling the extruded molten multifilaments by blowing air at a speed of 2.0 m / min to form solid multifilaments, a water-emulsified finishing agent containing 60% by weight of octyl stearate, 15% by weight of polyoxyethylene alkyl ether, and 3% by weight of potassium phosphate was applied to the fibers using a guide nozzle to a 10% by weight concentration of the water-emulsified finishing agent so that the amount of the oil deposited was 0.6% by weight.

[0185] The resulting solid multifilament was wound around a first heated roll heated to 50°C and running at a peripheral speed of 3200 m / min. It was then drawn 1.1 times around a second heated roll at 80°C. The resulting fiber was then wound using a winder that used both a driven spindle and a touch roller at a winding speed of 3360 m / min (overfeed ratio of 6%). The physical properties of the resulting polyester conjugate fiber are shown in Table 1.

[0186] The obtained polyester conjugate fiber was then subjected to stretching and false twisting under the following conditions at a stretching ratio of 1.1. The physical properties of the obtained polyester false twisted yarn are shown in Table 2. The obtained yarn had little crimp.

[0187] ・False twist conditions

[0188] False twist machine type: HTS-15V manufactured by TMT Machinery Co., Ltd. (disc false twist method)

[0189] Disc speed: 6260rpm (disc diameter 5.8cm)

[0190] Feed speed: 530m / min

[0191] First feed rate: ±0%

[0192] 1st heater temperature (non-contact type): 180°C

[0193] Second heater temperature (non-contact type): 200°C

[0194] Second feed nip roller speed: 600m / min

[0195] Second feed rate: 1.0%

[0196] Feed rate before coiling: 4.0%

[0197] [Comparative Example 6]

[0198] As in Example 1, poly(trimethylene terephthalate) having an intrinsic viscosity of 1.0 dl / g and a glass transition temperature of 45°C and poly(trimethylene terephthalate) having an intrinsic viscosity of 1.4 dl / g and a glass transition temperature of 46°C were melted separately at 265°C and extruded from a spinning nozzle heated at 265°C at a ratio of 50:50 and a total discharge rate of 15 g / min through a single-array spinning nozzle having 24 holes with a diameter of 0.3 mm using a spinneret with a parallel cross-section.

[0199] After rapidly cooling the extruded molten multifilaments by blowing air at a speed of 2.0 m / min to form solid multifilaments, a water-emulsified finishing agent containing 60% by weight of octyl stearate, 15% by weight of polyoxyethylene alkyl ether, and 3% by weight of potassium phosphate was applied to the fibers using a guide nozzle to a 10% by weight concentration of the water-emulsified finishing agent so that the amount of the oil deposited was 0.6% by weight.

[0200] The obtained solid multifilament was wound around an unheated first heating roll at a speed of 1000 m / min, and then taken up at a speed of 1000 m / min using a winder with a driven spindle and a touch roll.

[0201] Next, the obtained polyester conjugate fiber was subjected to stretching and false twisting under the same conditions as in Example 1. However, even when the stretch ratio was changed, the yarn tension was low and yarn breakage occurred, and a false twisted yarn could not be obtained.

[0202] [Comparative Example 7]

[0203] As in Example 1, poly(trimethylene terephthalate) having an intrinsic viscosity of 1.0 dl / g and a glass transition temperature of 45°C and poly(trimethylene terephthalate) having an intrinsic viscosity of 1.4 dl / g and a glass transition temperature of 46°C were melted separately at 265°C and extruded from a spinning nozzle heated at 265°C at a ratio of 50:50 and a total discharge rate of 19 g / min through a single-array spinning nozzle having 24 holes with a diameter of 0.3 mm using a spinneret with a parallel cross-section.

[0204] After rapidly cooling the extruded molten multifilaments by blowing air at a speed of 2.0 m / min to form solid multifilaments, a water-emulsified finishing agent containing 60% by weight of octyl stearate, 15% by weight of polyoxyethylene alkyl ether, and 3% by weight of potassium phosphate was applied to the fibers using a guide nozzle to a 10% by weight concentration of the water-emulsified finishing agent so that the amount of the oil deposited was 0.6% by weight.

[0205] The obtained solid multifilament was wound around an unheated first heating roller at a speed of 2600 m / min, then around a second heating roller at 2600 m / min, and then wound up at a winding speed of 2600 m / min using a winder that drives both a spindle and a touch roller.

[0206] The obtained polyester conjugate fiber showed significant deterioration over time, had a poor winding state, and was unable to stably sample the yarn due to winding constriction during winding.

[0207] Next, the obtained polyester conjugate fiber was subjected to stretching and false twisting under the same conditions as in Example 1. However, even when the stretch ratio was changed, the yarn tension was low and yarn breakage occurred, and a false twisted yarn could not be obtained.

[0208]

[0209]

[0210] Industrial applicability

[0211] According to the present invention, a polyester composite fiber false-twisted yarn can be provided which has a low initial elastic modulus, high crimping properties before boiling water treatment, and a small difference in crimping properties before and after boiling water treatment. When the yarn is used to make a fabric, the yarn not only has stretchability due to the high crimping properties, but also has the same crimping properties before and after boiling water treatment. The yarn is also less likely to shrink in subsequent steps such as dyeing, thereby enabling the production of a fabric with a soft texture.

Claims

1. A polyester composite fiber, characterized in that A composite fiber in which polyesters of different intrinsic viscosities are bonded together along the entire length of the fiber in a side-by-side, bonded, or eccentric core-sheath configuration, wherein the composite fiber simultaneously satisfies the following requirements (a) to (d): (a) The crystallization heat ratio of the composite fiber when heated is 10% to 60% relative to the completely amorphous state; (b) The breaking elongation of the composite fiber is 60-200%; (c) Breaking strength of composite fiber (cN / dtex) × elongation 1 / 2 (%) ≥10; (d) The peak temperature of the thermal stress of the conjugated fiber is not more than the glass transition temperature of the polyester component having a higher glass transition temperature among the polyester components constituting the conjugated fiber + 50° C., and the peak temperature of the thermal stress of the conjugated fiber is 0.05 to 0.8 cN / dtex.

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

3. A method for producing a polyester composite fiber, characterized in that: Polyesters with different intrinsic viscosities are melt-blown into composite fibers bonded in a parallel, bonded, or eccentric core-sheath configuration over the entire fiber length. The fibers are then taken up at a take-up speed of 1,000 to 3,000 m / min using a first heated roller having a temperature range of -30°C (-1°F) of the polyester component with the lower glass transition temperature and +30°C (1°F) of the polyester component with the higher glass transition temperature. The fibers are then heated and stretched using the first heated roller, wound around a second heated roller at a temperature of 30 to 120°C, and taken up at a take-up speed of 2,000 to 3,300 m / min.

4. A polyester false twist yarn, characterized in that: The polyester conjugate fiber according to claim 1 has crimps formed by false twisting, and satisfies the following requirements (1) to (4): (1) The elastic modulus at an elongation of 2% is less than 10 cN / dtex; (2) 10% ≤ Vc ≤ 50%; (3) 30% ≤ Tc ≤ 70%; (4)-20% ≤ Vc-Tc ≤ 20%.

5. The polyester false twist textured yarn according to claim 4, wherein The total fineness of the false twisted yarn is 10 to 200 dtex or less, and the tensile strength at break is 2.0 cN / dtex or more.

6. A method for producing polyester false twist yarn, characterized in that: The polyester conjugate fiber according to claim 1 is stretched and false-twisted. 7 . A polyester fiber structure comprising 5% by mass or more of the polyester conjugate fiber according to claim 1 and the polyester false twist textured yarn according to claim 4 .

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