False twist multifilament yarn

Abstract

This invention provides a novel false-twist multifilament yarn that has excellent yarn properties such as strength and elongation, and is sufficiently crimped by false-twist processing. When used in clothing or interior goods, it does not naturally disintegrate and can be used under normal conditions. Furthermore, when recycled after use, it can be melted at low temperatures into a resinous substance and molded into a shape that allows it to be pelletized again. [Solution] A false-twist multifilament yarn composed of single fibers formed from a copolymer polyester containing terephthalic acid as an acid component and ethylene glycol and 1,4-butanediol as glycol components, wherein the false-twist multifilament yarn has a breaking strength of 2.0 cN / dtex or more, an elongation at break of 45% or less, a crimping rate of 25-75%, and an elasticity recovery rate of 20-55%.

Description

[Technical Field]

[0001] The present invention relates to a false-twisted multifilament yarn that is composed of single fibers made of a specific copolymer polyester resin and that can be melted even at a low heat treatment temperature when recycled after use as a product. [Background technology]

[0002] In recent years, as part of efforts to protect the global environment, many efforts have been made to recycle products that use synthetic fibers, such as used clothing and interior goods. More specifically, used products such as clothing and interior goods made of synthetic fibers are treated at high temperatures to melt the synthetic fibers that make up the products, turning them into a resin-like substance, and molding them into a shape that can be repelletized.

[0003] If the heat treatment temperature for recycling used products could be lowered, it would be possible to recycle them in a more environmentally friendly manner. To achieve this, it would be possible to use synthetic fibers with low melting points for clothing and interior goods. Furthermore, such synthetic fibers are preferably false twisted yarns in order to impart bulkiness and texture to clothing and interior goods.

[0004] Since false twisting involves drawing and heat treatment, it is difficult to sufficiently false twist fibers made of low-melting-point resins. Previously, false twisted polylactic acid fibers have been proposed as false twisted yarns made of low-melting-point polyester resins (see Patent Document 1). However, polylactic acid is naturally degradable and deteriorates over time, making it difficult to use in a variety of applications.

[0005] Also proposed is a multifilament yarn obtained by subjecting a core-sheath composite fiber, in which a low-melting polyester resin is arranged in the sheath and a high-melting polyester resin is arranged in the core, to false twisting (see Patent Document 2). However, this false twist textured yarn is designed to be used by melting the low melting point polyester resin in the sheath, and the yarn quality performance as a false twist textured yarn is achieved by the high melting point polyester resin in the core.

[0006] In other words, it is a multifilament yarn made of single fibers formed from a low-melting point polyester resin, has excellent yarn quality such as strength and elongation, and is sufficiently crimped by false twist processing, so that when used in clothing, interior goods, etc., it can be used normally without naturally disintegrating, but on the other hand, no false twist processed yarn has yet been proposed that can be melted at low temperature to form a resin-like substance and molded into a shape that can be pelletized again when recycled after use. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2002-155437 [Patent Document 2] Japanese Patent Publication No. 2015-117444 [Overview of the Initiative] [Problem to be solved by the invention]

[0008] The present invention solves the above-mentioned problems, and has as its technical object the provision of a new false-twisted multifilament yarn that has excellent yarn quality such as strength and elongation, is sufficiently crimped by false-twist processing, and can be used normally without spontaneously disintegrating when used in clothing, interior goods, etc., while when recycled after use, it can be melted at low temperature to form a resinous material and molded into a shape that can be pelletized again. [Means for solving the problem]

[0009] The present invention is summarized as follows (i) to (iv). (i) A false-twist multifilament yarn composed of monofibers formed from a copolymer polyester containing terephthalic acid as an acid component and ethylene glycol and 1,4-butanediol as glycol components, which satisfies all of the following characteristic values ​​(1) to (4). (1) Cutting strength 2.0cN / dtex or more (2) Cutting elongation 45% or less (3) Crimp rate 25~75% (4) Elastic recovery rate: 20-55% (ii) A false twist multifilament yarn according to (i), having a melting point of 200°C or less. (C) A false-twisted multifilament yarn according to (A), having a torque of 70 to 140 T / M and an entanglement number of 0 to 90 (pieces / m). (d) The false-twisted multifilament yarn according to (a), having a hot water shrinkage rate of 3 to 15%. [Effects of the Invention]

[0010] The false-twisted multifilament yarn of the present invention has excellent yarn quality such as strength and elongation, and is sufficiently crimped by the false-twist processing, so it can be used normally without natural collapse.On the other hand, when it is recycled after use, it can be melted at low temperature to form a resin-like substance and molded into a shape that can be pelletized again, making it highly recyclable. The false-twisted multifilament yarn of the present invention can be suitably used for clothing, interior goods, etc. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a process diagram showing an example of a method for producing a false-twisted multifilament yarn of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below. The false-twisted multifilament yarn of the present invention is composed of single fibers formed from a copolymer polyester containing a terephthalic acid component, an ethylene glycol component, and a 1,4-butanediol component. The copolymer polyester forming the single fiber contains a terephthalic acid component as an acid component, and when the total acid components are taken as 100 mol %, it preferably contains 80 mol % or more of terephthalic acid, more preferably 90 mol % or more, and even more preferably 95 mol % or more.

[0013] As long as the effects of the present invention are not impaired, acid components other than terephthalic acid may include isophthalic acid, 5-sodium sulfoisophthalic acid, phthalic anhydride, naphthalenedicarboxylic acid, trimellitic acid, pyromellitic acid, adipic acid, azelaic acid, sebacic acid, dodecanoic diacid, 4-hydroxybenzoic acid, and the like.

[0014] The copolymer polyester forming the single fiber contains ethylene glycol and 1,4-butanediol as glycol components. When the total glycol components are 100 mol %, the ethylene glycol content is preferably 40 to 70 mol %, and more preferably 45 to 65 mol %. Furthermore, the 1,4-butanediol content is preferably 30 to 60 mol %, and more preferably 33 to 55 mol %.

[0015] As long as the effects of the present invention are not impaired, glycol components other than ethylene glycol and 1,4-butanediol may include ε-caprolactone, diethylene glycol, 1,4-cyclohexanedimethanol, neopentyl glycol, pentaerythritol, 2,2-bis{4-(β-hydroxy)phenyl}propane, and the like.

[0016] The copolymer polyester of the present invention described above has a low melting point but a relatively fast crystallization rate, and is therefore preferred in that it is highly stable not only during spinning but also during the drawing process and false twisting. The melting point is preferably 130 to 200°C, more preferably 130 to 180°C, and even more preferably 130 to 160°C. The glass transition point is preferably 20 to 80°C, and the crystallization onset temperature is preferably 90 to 130°C.

[0017] The single fibers constituting the false-twisted multifilament yarn of the present invention preferably have a fineness (single fiber fineness) of 0.1 to 30 dtex, and more preferably 1 to 20 dtex. The cross-sectional shape of the single fibers is not particularly limited and may be any shape such as round, triangular, or cross-shaped. The total fineness of the false-twisted multifilament yarn of the present invention composed of these single fibers is preferably 50 to 350 dtex, more preferably 60 to 300 dtex, and more preferably 100 to 250 dtex.

[0018] As described above, the false-twisted multifilament yarn of the present invention is made of a low-melting point copolymer polyester resin, but it has strength and elongation that allow it to be used without any problems in normal applications such as clothing and interior goods, and it is imparted with sufficient crimp. Such false twisted multifilament yarn of the present invention has only been obtained by the manufacturing method described below.

[0019] The false-twist multifilament yarn of the present invention has a breaking strength of 2.0 cN / dtex or higher, preferably 2.2 cN / dtex or higher. Furthermore, its elongation at break is 45% or less, preferably 40% or less. Due to these strengths and elongations, woven or knitted fabrics obtained using the false-twist multifilament yarn of the present invention can be used without any problems in normal use when used for clothing, interior goods, etc.

[0020] The false-twisted multifilament yarn of the present invention is three-dimensionally crimped by false-twisting, and has a crimp percentage of 20 to 75%, preferably 25 to 70%, and a stretch recovery percentage of 20 to 55%, preferably 25 to 45%.

[0021] By having the crimp rate and stretch recovery rate at or above the above values, it is possible to obtain effective bulkiness when the yarn is made into a woven or knitted fabric. The higher the crimp rate and stretch recovery rate, the more bulkiness can be imparted, but according to the manufacturing method described below, if the crimp rate exceeds 75% and the stretch recovery rate exceeds 55%, the false twist heater temperature must be set high, which can lead to frequent occurrence of textured yarn breakage, fuzz, partial fusion, etc., making it difficult to efficiently obtain textured yarn with stable quality.

[0022] As an indicator of a state in which the false-twisted multifilament yarn of the present invention has been sufficiently three-dimensionally crimped, a torque of 70 to 140 T / M is preferred, with 80 to 120 T / M being particularly preferred, and the number of entanglements is preferably 0 to 90 (pieces / m), with 0 to 85 (pieces / m) being particularly preferred.

[0023] Furthermore, the false-twisted multifilament yarn of the present invention preferably has a hot water shrinkage of 3 to 15%, and more preferably 5 to 13%. A hot water shrinkage within the above range can impart appropriate volume and stretchability to the resulting woven or knitted fabric. If the hot water shrinkage is less than 3%, shrinkage when woven into a fabric is insufficient, resulting in a low crimp rate in the dyed and finished product, making it difficult to achieve satisfactory stretchability. On the other hand, if the hot water shrinkage exceeds 15%, the yarn becomes too sensitive to heat, resulting in uneven partial shrinkage during sizing and drying, which are employed in the pre-weaving process, and in the dyeing and finishing process, which can easily degrade the quality of the woven or knitted fabric.

[0024] The false twisted multifilament yarn of the present invention has a melting point of 200° C. or less, and preferably 190° C. or less. Because the false twisted multifilament yarn of the present invention is made of the low melting point copolymer polyester resin described above, it can be made into a yarn with a low melting point, and the heat treatment temperature can be lowered when melting it during recycling, resulting in excellent energy efficiency.

[0025] Next, an example of a method for producing the false-twisted multifilament yarn of the present invention will be described. The false-twisted multifilament yarn of the present invention is preferably produced by melt-spinning a copolymer polyester resin having the specific components described above to obtain a partially oriented undrawn yarn, which is then subjected to false-twist processing. The partially oriented undrawn yarn can be obtained by melt-spinning in a conventional manner. Specifically, a copolymer polyester resin having the specific components described above is kneaded and melted using a conventional melt-spinning apparatus, for example, an extruder, extruded through a spinneret, cooled and solidified, and then melt-spun at a speed of 2000 m / min or more to obtain a highly oriented undrawn yarn Y. The yarn quality of the highly oriented undrawn yarn preferably has a strength of 1.5 to 3 cN / dtex and an elongation of 90 to 200%.

[0026] The obtained highly oriented undrawn yarn Y is supplied to the false-twist processing area between the supply roller 1 and the first take-up roller 4, as shown in Figure 1, and is false-twisted using the false-twist heater 2 and the false-twisting device 3 to become false-twisted yarn. The false twisted yarn is then passed through a first take-up roller 4 and guided to a fluid treatment processing zone, where a fluid is sprayed onto the yarn from a fluid nozzle 5, to produce the false twisted multifilament yarn of the present invention. The resulting false twisted multifilament yarn passes through a second take-up roller 6 and is wound onto a package 8 by a winding roller 7.

[0027] Examples of false twisting devices 3 include pin, belt, and friction disk types, but a belt-type false twisting device is preferred because it is suitable for the low-melting-point copolymer polyester resin of the present invention and from the standpoints of cost and processing operability. The fluid treatment step can be selected depending on whether or not there are problems with unwinding from the package 8. In the case of long packages that are prone to unwinding problems, it is desirable to use a fluid nozzle 5. A Taslan nozzle or an interlace nozzle is preferred as the fluid nozzle 5, with the interlace nozzle being particularly preferred.

[0028] The overfeed rate at this time is preferably 1 to 5%. The overfeed rate is calculated by the formula: Overfeed rate = (V1 - V2) / V2 × 100 (%), where V1 is the yarn speed at the first take-up roller 4 immediately before being introduced into the fluid nozzle 5, and V2 is the yarn speed at the second take-up roller 6 immediately after passing through the fluid nozzle.

[0029] The false-twisted multifilament yarn of the present invention can be woven or knitted into fabrics for clothing or interior goods. Examples of woven fabrics using the false-twisted multifilament yarn of the present invention include plain weave, twill, satin weave, dobby weave, and double weave, and examples of knitted fabrics include circular knitting, weft knitting, and warp knitting.

[0030] Since the false-twisted multifilament yarn of the present invention has good thermal efficiency when recycled, it is preferable that when knitting or weaving, no other multifilaments are used, and that only the false-twisted multifilament yarn of the present invention is used. [Example]

[0031] The present invention will now be described in more detail with reference to examples, in which the methods for measuring and evaluating various properties are as follows: <Total fineness> The obtained false-twisted multifilament yarn was used as a sample, and the total fineness (rounded to the first decimal place) was measured according to the method specified in "8.3.1 Correct fineness" of "JIS L-1013:2010 Test method for chemical fiber filament yarn." <Strength and elongation> The obtained false-twisted multifilament yarn was used as a sample to measure the breaking strength and breaking elongation in accordance with JIS L1013 8.5.2. The measurements were performed using a constant-speed extension type tensile tester (Shimadzu Corporation, Autograph AGS-5KNG) under the conditions of a sample length of 200 mm and a pulling speed of 200 mm / min.

[0032] <Crimp rate> The resulting false-twisted multifilament yarn was used as a sample. A 1.125 m circumference measuring machine was used to wind five skeins, which were then hung on a stand at room temperature in a free state for 24 hours. The skein was then placed in boiling water under a load of 0.000147 cN / dtex for 30 minutes for a moist, hot water treatment. The skein was then removed, lightly wiped dry with filter paper, and left at room temperature for 30 minutes under a load of 0.000147 cN / dtex. A load of 0.00177 cN / dex (light load) was then applied to the skein, and the length X was measured. Next, a load of 0.044 cN / dtex (heavy load) was applied instead of the light load, while the 0.000147 cN / dtex load was still applied, and the length Y was measured. Subsequently, the crimp rate (%) is calculated based on the formula: crimp rate (%) = (YX) / Y × 100. To measure the crimp rate, prepare five samples, perform the procedure described above for each, and use the average of the five calculated crimp rates.

[0033] <Stretch recovery rate> The resulting false-twisted multifilament yarn was used as a sample, and after five windings were taken into a skein using a measuring machine with a frame circumference of 1.125 m, the skein was hung on a stand in a free state at room temperature for a day and a night. Next, this skein was subjected to a hot water treatment in 90°C water for 20 minutes, and the polyester composite yarn was then measured for its stretch recovery rate according to the method specified in "8.12 Stretch Recovery Rate" of "JIS L-1013:2010 Test Methods for Chemical Fiber Filament Yarns."

[0034] <Number of Intertwinings> The obtained false-twisted multifilament yarn was used as a sample, and the number of confoundings (degree of confounding) was measured according to the method specified in "8.15 Degree of Confounding" of "JIS L-1013:2010 Test Methods for Chemical Fiber Filament Yarns".

[0035] <torque> The resulting false-twisted multifilament was used as a sample. It was hung in a U-shape with a sample length of 200 cm, and a hook was attached and held at the bottom end 1 m. A load of 0.0294 (cN / dtex) was applied to each of the top ends of the sample to tension the sample. Next, with the load applied, the vicinity of each of the top ends of the sample was fixed with fixtures, and then the load was released. A load of 0.00294 (cN / dtex) was then applied to the bottom end of the U-shaped sample. This caused the sample to rotate in the direction of the U-shape twist, and the number of twists per meter was determined when the sample stopped rotating, and this number of twists was calculated as torque.

[0036] <Hot water shrinkage rate> The obtained false-twisted multifilament yarn was used as a sample, and the skein size change rate (Method A) specified in "8.18.1 Hot Water Dimension Change Rate" of "JIS L-1013:2010 Test Methods for Chemical Fiber Filament Yarns" was measured under the condition of immersion in 100°C hot water for 30 minutes, and this value was defined as the hot water shrinkage rate. <Processed thread breakage and fluff> The number of broken fluffs (per 1 kg of winding) on ​​both end surfaces of the false twist multifilament yarn wound onto a package was visually counted and evaluated on the following two-level scale. Good: Number of fluffs is 5 or less (good with little fluff) ×: 6 or more fluffs (lots of fluff) <Melting evaluation> The obtained false-twist multifilament yarn was prepared by winding it 10 times using a measuring machine with a frame circumference of 90 cm, and then subjected to dry heat treatment at 200°C for 5 minutes in a Shimadzu Corporation STAC-S50M hot air low-temperature dryer. The condition of the false-twist multifilament yarn after heat treatment was visually inspected and evaluated in the following two stages. 〇: Melted (False twist multifilament yarn has turned into resin) ×: No melting (shrinkage occurs, but the shape of the false-twisted multifilament yarn is maintained)

[0037] Example 1 (Highly oriented undrawn yarn) Copolymer polyester resin: A slurry of terephthalic acid (TPA) and ethylene glycol (EG) was fed into an esterification reactor and reacted at a temperature of 250°C and a pressure of 50 hPa to obtain a reaction product with an esterification reaction rate of 95%. The reaction product of TPA and EG, 1,4-butanediol, a polymerization catalyst, and titanium oxide were added, and the reactor was decompressed to carry out a melt polymerization reaction, yielding a copolymer polyester resin (copolymerized with 46 mol% of 1,4-butanediol as the glycol component, melting point 181°C, intrinsic viscosity 0.58 dL / g). The titanium oxide content was 0.3% by mass.

[0038] The above copolymer polyester resin was supplied to a spinning apparatus, and the melt-spun yarn was spun from a 280°C nozzle. The yarn was cooled by blowing cooling air (at a temperature of 24°C) at a position 130 mm from the bottom of the nozzle, and then bundled and oiled. The yarn was then taken up at a speed of 3000 m / min on a take-up roller to obtain a highly oriented undrawn yarn Y. The obtained highly oriented undrawn yarn Y had a total fineness of 255 dtex, a filament count of 48 f, a strength of 1.95 cN / dtex, an elongation of 113%, and a boiling water shrinkage rate of 62%.

[0039] This highly oriented undrawn yarn Y was used as the supply yarn, and a belt-type nip twister "Mach 33H Belt Type" manufactured by Murata Machinery Co., Ltd. was used as the twisting device for false twisting, and the highly oriented undrawn yarn Y was draw-false-twisted under the conditions shown in Table 1 to obtain a false-twisted multifilament yarn. That is, according to the production process shown in Figure 1, the highly oriented undrawn yarn Y was supplied to supply rollers 1 and draw-false-twisted using heater 2 (full-surface contact heater) and belt-type false twisting device 3 installed between first take-up rollers 4. Next, the highly oriented undrawn yarn Y was subjected to a mixed fiber entanglement process using fluid nozzle 5 installed between first take-up roller 4 and second take-up roller 6 to obtain a false-twisted multifilament yarn (wound into a package). An interlace nozzle ("P-212" manufactured by Heberlein) was used as the fluid nozzle, and the obtained false-twisted multifilament yarn had entangled portions and unentangled portions (open portions) in the yarn longitudinal direction.

[0040] Example 2 Using the highly oriented undrawn yarn Y obtained in Example 1, a Mitsubishi LS-6 pin false twister was used as the twisting device for false twisting, and the processing speed was set to 110 m / min. Except that interlacing treatment was not performed, the drawn false twisting process was carried out under the same conditions as in Example 1 to obtain false twisted multifilament yarn.

[0041] Comparative Example 1 Using the highly oriented undrawn yarn Y obtained in Example 1, a draw-and-friction twist process was performed under the same conditions as in Example 1, except that the false twist heater temperature during false twisting was set to a high 160°C, to obtain a false twist multifilament yarn.

[0042] Comparative Example 2 Using the highly oriented undrawn yarn Y obtained in Example 1, a draw-and-friction twist process was performed under the same conditions as in Example 1, except that the false twist temperature was set to 90°C, which is below the limit temperature, to obtain a false twist multifilament yarn.

[0043] Comparative Example 3 Using the highly oriented undrawn yarn Y obtained in Example 1, a draw and false twist process was performed under the same conditions as in Example 1, except that the draw ratio was set low at 1.35 times, to obtain a false twist multifilament yarn.

[0044] Comparative Example 4 In Example 1, a highly oriented undrawn polyethylene terephthalate (PET) yarn was used instead of the highly oriented undrawn yarn Y. This PET yarn had a total fineness of 255 dtex, a filament count of 48 f, a strength of 2.64 cN / dtex, an elongation of 120%, and a boiling water shrinkage of 46.3%. Using this highly oriented undrawn PET yarn, a Teijin HTS-1500 disc-type twisting machine (disk configuration: 1-6-K (3-axis external friction unit), disk thickness: 9 mm) was used as the twisting device for false twisting. A false twist multifilament yarn of 168 dtex / 48 f was obtained under the false twisting conditions shown below, following the manufacturing process shown in Figure 1. <False twist conditions> • Speed ​​of the first pull roller 4: 500 m / min ·Stretching ratio: 1.57x False twist heater 2 temperature (S / L): 470 / 260℃ ·Twisting direction: Z direction K value: 0.78 Fluid nozzle 5: Heberlein P212 Air pressure: 0.25 MPa I / L Zone OF Rate: 1.5%

[0045] [Table 1]

[0046] As is clear from Table 1, the false-twisted multifilament yarns obtained in Examples 1 and 2 exhibited excellent yarn properties such as strength and elongation, and were sufficiently crimped by the false-twisting process. Furthermore, they melted into a resinous state upon low-temperature heat treatment. [Explanation of symbols]

[0047] Y Highly oriented undrawn yarn 1 Supply roller 2 False twist heater 3 False twisting device 4 First take-up roller 5 Fluid Nozzles 6 Second take-off roller 7 Winding roller 8 packages

Claims

1. A false-twisted multifilament yarn composed of single fibers formed from a copolymer polyester containing terephthalic acid as an acid component and ethylene glycol and 1,4-butanediol as glycol components, the false-twisted multifilament yarn satisfying all of the following characteristic values ​​(1) to (4): (1) Cutting strength 2.0cN / dtex or more (2) Cutting elongation 45% or less (3) Crimp rate 25-75% (4) Elasticity recovery rate: 20-55%

2. 2. The false twist multifilament yarn according to claim 1, having a melting point of 200°C or less.

3. 2. The false twist multifilament yarn according to claim 1, wherein the torque is 70 to 140 T / M and the number of entanglements is 0 to 90 (pieces / m).

4. 2. The false twist multifilament yarn according to claim 1, having a hot water shrinkage rate of 3 to 15%.

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