CRIMPED POLESTER-BASED FIBER, METHOD FOR PRODUCING SAME, PILE FABRIC INCLUDING SAME, AND METHOD FOR PRODUCING PILE FABRIC

Abstract

 In one or more embodiments, the present invention relates to a polyester-based fiber having a crimp with a crimped shape to be changed by a dry heat treatment at 150°C for 10 minutes. It is preferable that the polyester-based fiber having a crimp according to one or more embodiments of the present invention has a crimp satisfying requirements described in (1) below before the dry heat treatment and has a crimp having a secondary crimp frequency satisfying 0.0 crimps/25 mm or more and 1.0 crimps/25 mm or less after the dry heat treatment:
(1) a primary crimp frequency of 5.0 crimps/25 mm or more and 30 crimps/25 mm or less and a secondary crimp frequency of 1.0 crimps/25 mm or more and 4.0 crimps/25 mm or less.
In one or more embodiments, the present invention provides a polyester-based fiber exhibiting good processability in a carding machine and being able to express a crimp similar to that of natural fur in a napped surface layer portion of a pile fabric through polishing at a relatively low temperature of 90°C or more and 160°C or less, a method for manufacturing the same, and a method for manufacturing a pile fabric using the same.

Description

Technical Field

[0001] The present invention relates to polyester-based fibers having a crimp with a crimped shape to be changed by a heat treatment, a method for manufacturing the same, a pile fabric including the same, and a method for manufacturing a pile fabric.

Background Art

[0002] Conventionally, acrylic fibers and/or modacrylic fibers, which have very similar texture and gloss to animal hair, have been widely used as pile fibers in a pile fabric as artificial fur that resembles natural fur. However, acrylic fibers and modacrylic fibers have poor elasticity and lack firmness, and thus a pile fabric in which these fibers are used has inferior recovering strength and voluminousness in use and is different from natural fur.

[0003] Thus, it has been proposed to use polyester-based fibers as pile fibers. A pile fabric in which polyester-based fibers are used has good recovering strength and voluminousness. However, if the temperature in polishing in the production of a pile fabric is low, crimps on pile fibers in a napped surface layer portion are not sufficiently removed, and the pile fibers are entangled with each other, resulting in a rough feel. Moreover, even when crimps are removed by polishing at a high temperature, the shape of the fibers in a napped portion is completely different from that of natural fur. Furthermore, it is commonly said that a pile fabric in which polyester-based fibers are used needs to be polished at a temperature close to 200°C, and from the viewpoint of heat resistance, it has been difficult to use polyester-based fibers in combination with acrylic fibers and modacrylic fibers that have been used conventionally.

[0004] Thus, Patent Document 1 proposes that the crimp removability of polyester-based fibers be improved by adjusting, e.g., a fiber cross-section, fineness, fiber length, crimp frequency, percentage of crimp, and crimp fastness. Patent Document 2 proposes that the crimp removability of polyester-based fibers in polishing be improved by imparting a crimp after a heat treatment at 160°C to 230°C is performed under conditions in which shrinkage is restricted to 1% to 7% in a spinning process.

Prior Art Documents

Patent Documents

[0005] 

Patent Document 1: JP S60-162857 A

Patent Document 2: JP H05-140860 A

Disclosure of Invention

Problem to be Solved by the Invention

[0006] Meanwhile, it is common that a sliver is often used to be processed into a pile fabric, and pile fibers are required to exhibit good processability in a carding machine.

[0007] The polyester-based fibers proposed in Patent Documents 1 and 2 exhibit good processability in a carding machine, and crimps can be removed by polishing in manufacturing a pile fabric. However, the appearance of a napped portion, particularly of a napped surface layer portion in the obtained pile fabric is different from the appearance of a napped surface layer portion of natural fur, and needs to be further improved. The reason for this is described as follows. Although crimps are imparted on these polyester-based fibers by a mechanical stuff crimping, it is difficult to control the crimped shape of the fibers after polishing such that the shape closely resembles the crimped shape similar to that of natural fur, and after polishing, the crimps imparted by the mechanical stuff crimping remain on the fibers as they are or in a state in which the crimps are relaxed. Moreover, in the case of fur of, e.g., a mink or fox constituted by a guard hair portion and a down hair portion and having a difference in level, the guard hair portion is straight while a gentle crimp is imparted on the down hair portion, and it is still more difficult to allow the appearance of an artificial pile fabric to closely resemble that of natural fur.

[0008] In order to solve the conventional problems as described above, the present invention provides polyester-based fibers exhibiting good processability in a carding machine and being able to express a crimp similar to that of natural fur in a napped surface layer portion of a pile fabric through polishing at a relatively low temperature of 90°C or more and 160°C or less, a method for manufacturing the same, a pile fabric including the same, and a method for manufacturing a pile fabric.

Means for Solving Problem

[0009] In one or more embodiments, the present invention relates to a polyester-based fiber having a crimp with a crimped shape to be changed by a dry heat treatment at 150°C for 10 minutes.

[0010] It is preferable that the polyester-based fiber having a crimp according to one or more embodiments of the present invention has a crimp satisfying requirements described in (1) below before the dry heat treatment and has a crimp having a secondary crimp frequency of 0 crimps/25 mm or more and 1 crimps/25 mm or less after the dry heat treatment:

(1) a primary crimp frequency of 5 crimps/25 mm or more and 30 crimps/25 mm or less and a secondary crimp frequency of 1 crimps/25 mm or more and 4 crimps/25 mm or less.
It is more preferable that the polyester-based fiber according to one or more embodiments of the present invention has a crimp satisfying the above requirements described in (1) before the dry heat treatment and has a crimp satisfying requirements described in (2) below after the dry heat treatment:

(2) a primary crimp frequency of 3 crimps/25 mm or more and 8 crimps/25 mm or less and a secondary crimp frequency of 0 crimps/25 mm or more and 1 crimps/25 mm or less.

[0011] In one or more embodiments, the present invention relates to a method for manufacturing a polyester-based fiber including, in a crimp imparting process 1, imparting a crimp satisfying requirements described in (2) below at a temperature of 130°C or more and 230°C or less on a polyester-based fiber that is not subjected to heat of 150°C or more in a spinning process before crimping, and then, in a crimp imparting process 2, crimping the polyester-based fiber at a temperature of 70°C or more and 130°C or less, to obtain a polyester-based fiber having a crimp satisfying requirements described in (1) below:

(1) a primary crimp frequency of 5.0 crimps/25 mm or more and 30.0 crimps/25 mm or less and a secondary crimp frequency of 1.0 crimps/25 mm or more and 4.0 crimps/25 mm or less; and

(2) a primary crimp frequency of 3.0 crimps/25 mm or more and 8.0 crimps/25 mm or less and a secondary crimp frequency of 0.0 crimps/25 mm or more and 1.0 crimps/25 mm or less.

[0012] In one or more embodiments, the present invention relates to a method for manufacturing a pile fabric including producing a pile fabric including the polyester-based fiber in an amount of 30% by weight or more in a pile portion as a whole.

[0013] It is preferable that in the method for manufacturing a pile fabric according to one or more embodiments of the present invention, the polyester-based fiber is polished at a temperature of 90°C or more and 160°C or less. In the method for manufacturing a pile fabric according to one or more embodiments of the present invention, the pile fabric may include a long pile portion and a short pile portion, and a difference between an average pile length of the long pile portion and an average pile length of the short pile portion may be 2 mm or more. In the method for manufacturing a pile fabric according to one or more embodiments of the present invention, the pile fabric may include the polyester-based fiber in the short pile portion. In the method for manufacturing a pile fabric according to one or more embodiments of the present invention, the long pile portion may include a modacrylic fiber constituted by an acrylic-based copolymer containing acrylonitrile in an amount of 35% by weight or more and less than 95% by weight.

[0014] In one or more embodiments, the present invention relates to a pile fabric including the polyester-based fiber in an amount of 30% by weight or more with respect to a pile portion as a whole. The polyester-based fiber has a crimp having a primary crimp frequency of 3.0 crimps/25 mm or more and 8.0 crimps/25 mm or less and a secondary crimp frequency of 0.0 crimps/25 mm or more and 1.0 crimps/25 mm or less.

Effects of the Invention

[0015] With the present invention, it is possible to provide polyester-based fibers exhibiting good processability in a carding machine and being able to express a crimp similar to that of natural fur in a napped surface layer portion of a pile fabric through polishing at a relatively low temperature of 90°C or more and 160°C or less, and a pile fabric including the polyester-based fibers. With the manufacturing methods of the present invention, it is possible to obtain polyester-based fibers exhibiting good processability in a carding machine and being able to express a crimp similar to that of natural fur in a napped surface layer portion of a pile fabric through polishing at a relatively low temperature of 90°C or more and 160°C or less, and a pile fabric.

Brief Description of Drawings

[0016] 

[FIG. 1] FIG. 1 is a view illustrating a primary crimp and a secondary crimp.

[FIG. 2] FIG. 2 is a view illustrating criteria for evaluating the appearance of a pile fabric.

Description of the Invention

[0017] The present inventors conducted intensive studies to solve the above-described problems. As a result of this, the inventors found that it was possible to suitably use, in a pile fabric, polyester-based fibers that had a crimped shape suitable for ensuring processability in a carding machine during the passage of the fibers through a carding machine and were able to express a crimp similar to that of natural fur in pile fabric processing after the passage of the fibers through the carding machine. In other words, in one or more embodiments, polyester-based fibers of the present invention are polyester-based fibers having a crimp with a crimped shape to be changed by a dry heat treatment at 150°C for 10 minutes. Moreover, the present inventors found that the polyester-based fibers having a crimp in which a crimped shape satisfying requirements described in (1) below was changed into a crimped shape satisfying a secondary crimp frequency of 0 crimps/25 mm or more and 1 crimps/25 mm or less by the dry heat treatment exhibited better processability in a carding machine and were able to express a crimp more similar to that of natural fur in a napped portion, particularly in a napped surface layer portion of a pile fabric through polishing at a relatively low temperature of 90°C or more and 160°C or less. Furthermore, the present inventors found that the polyester-based fibers having a crimp in which a crimped shape was changed into a crimped shape satisfying requirements described in (2) below by the dry heat treatment exhibited good processability in a carding machine and were able to express a crimp even more similar to that of natural fur in a napped portion, particularly in a napped surface layer portion of a pile fabric through the polishing.

[0018] In addition, the present inventors found that polyester-based fibers having a crimp satisfying the requirements described in (1) below were able to be obtained by imparting a crimp satisfying the requirements described in (2) below at a temperature of 130°C or more and 230°C or less on polyester-based fibers that were not subjected to heat of 150°C or more in a spinning process before crimping, and then crimping the polyester-based fibers at a temperature of 70°C or more and 130°C or less. Specifically, the present inventors found that polyester-based fibers having a crimp satisfying the requirements described in (1) below were able to be obtained by, in a crimp imparting process 1, imparting a crimp satisfying the requirements described in (2) below at a temperature of 130°C or more and 230°C or less on polyester-based fibers that were not subjected to heat of 150°C or more in melt spinning a polyester-based resin or a polyester-based resin composition into yarns and drawing the yarns to produce drawn yarns or in subjecting drawn yarns to a heat treatment to produce heat treated yarns, and then, in a crimp imparting process 2, crimping the polyester-based fibers at a temperature of 70°C or more and 130°C or less. When the polyester-based fibers thus obtained were subjected to a dry heat treatment at 150°C for 10 minutes, the polyester-based fibers exhibited crimp characteristics in which the crimped shape satisfying the requirements described in (1) below was changed into a crimped shape satisfying the requirements described in (2) below. When a pile fabric was produced using the polyester-based fibers exhibiting such crimp characteristics, processability in a carding machine was good, and it was possible to obtain a pile fabric expressing a crimp similar to that of natural fur in a napped portion, particularly in a napped surface layer portion through polishing at a relatively low temperature of 90°C or more and 160°C or less.

(1) A primary crimp frequency of 5.0 crimps/25 mm or more and 30.0 crimps/25 mm or less and a secondary crimp frequency of 1.0 crimps/25 mm or more and 4.0 crimps/25 mm or less.

(2) A primary crimp frequency of 3.0 crimps/25 mm or more and 8.0 crimps/25 mm or less and a secondary crimp frequency of 0.0 crimps/25 mm or more and 1.0 crimps/25 mm or less.

[0019] In one or more embodiments of the present invention, as the polyester-based resin constituting the polyester-based fibers, though it is not particularly limited, it is possible to use, e.g., at least one selected from the group consisting of polyalkylene terephthalate and a copolyester containing polyalkylene terephthalate as a main component. Examples of the polyalkylene terephthalate include, but are not particularly limited to, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polytrimethylene terephthalate. In particular, from the viewpoint of heat characteristics, polyethylene terephthalate is preferable. Examples of the copolyester containing polyalkylene terephthalate as the main component include, but are not particularly limited to, copolyesters containing polyalkylene terephthalate such as polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, or polytrimethylene terephthalate as the main component and other copolymer components. In particular, from the viewpoint of heat characteristics, the copolyester containing polyethylene terephthalate as the main component is preferable. In the present invention, the term "main component" means a component contained in an amount of 50 mol% or more, and the term "copolyester containing polyalkylene terephthalate as the main component" refers to a copolyester containing polyalkylene terephthalate in an amount of 50 mol% or more. The "copolyester containing polyalkylene terephthalate as the main component" contains polyalkylene terephthalate preferably in an amount of 60 mol% or more, more preferably in an amount of 70 mol% or more, and further preferably in an amount of 80 mol% or more.

[0020] Examples of the other copolymer components include the following: polycarboxylic acids such as isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, paraphenylenedicarboxylic acid, trimellitic acid, pyromellitic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid, and their derivatives; dicarboxylic acids including a sulfonic acid salt such as 5-sodiumsulfoisophthalic acid and dihydroxyethyl 5-sodiumsulfoisophthalate, and their derivatives; and 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, diethylene glycol, polyethylene glycol, trimethylolpropane, pentaerythritol, 4-hydroxybenzoic acid, ε-caprolactone, and ethylene glycol ether of bisphenol A. These other copolymer components may be used alone or in combination of two or more.

[0021] Specific examples of the copolyester containing polyalkylene terephthalate as the main component include polyesters obtained through copolymerization of polyethylene terephthalate as the main component with one or more compounds selected from the group consisting of ethylene glycol ether of bisphenol A, 1,4-cyclohexanedimethanol, isophthalic acid, and dihydroxyethyl 5-sodiumsulfoisophthalate.

[0022] The polyalkylene terephthalate and the copolyesters containing polyalkylene terephthalate as the main component may be used alone or in a combination of two or more. In particular, it is preferable that the following are used alone or in a combination of two or more: polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, a polyester obtained through copolymerization of polyethylene terephthalate as the main component with ethylene glycol ether of bisphenol A, a polyester obtained through copolymerization of polyethylene terephthalate as the main component with 1,4-cyclohexanedimethanol, a polyester obtained through copolymerization of polyethylene terephthalate as the main component with isophthalic acid, and a polyester obtained through copolymerization of polyethylene terephthalate as the main component with dihydroxyethyl 5-sodiumsulfoisophthalate.

[0023] The intrinsic viscosity (IV value) of the polyester-based resin is not particularly limited, but is preferably 0.3 or more and 1.2 or less, and more preferably 0.4 or more and 1.0 or less. When the intrinsic viscosity thereof is 0.3 or more, the mechanical strength of fibers obtained does not decrease. Moreover, when the intrinsic viscosity is 1.2 or less, the molecular weight is not too large, and the melt viscosity is not too high. Thus, it is easy to perform melt spinning, and the fineness of the fibers obtained is likely to be uniform.

[0024] An additive agent such as a delustering agent, a lubricant, an antioxidant, a color pigment, a stabilizing agent, a flame retardant, or a toughening agent may be added to the polyester-based fibers as needed, for example. The delustering agent may be, e.g., titanium dioxide. Examples of the lubricant include silica microparticles and alumina microparticles.

[0025] In one or more embodiments of the present invention, the polyester-based fibers have a crimp with a crimped shape to be changed by the dry heat treatment at 150°C for 10 minutes. Here, the crimp refers to a periodic shape that is not straight and is imparted in an axial direction of a fiber. The crimped shape to be changed refers to the change of a certain crimped shape into a different crimped shape, specifically the change of crimp characteristics such as a primary crimp frequency and a secondary crimp frequency or the visual shape of the crimp. The shape of the crimp may be zigzag, wavy, or spiral, but is not limited to these. Hereinafter, a crimped shape 1 means a crimped shape before the dry heat treatment, a crimped shape 2 means a crimped shape after the dry heat treatment.

[0026] In one or more embodiments of the present invention, the dry heat treatment refers to a treatment of applying heat using dry air as a medium. Moreover, the dry heat treatment here is not particularly limited as long as the dry heat treatment is performed in a state where no load is applied, that is, no tension is applied in the axial direction of the fibers intentionally. Specifically, the fibers are allowed to stand still in a hot-air convection dryer set at 150°C in a state where no load is applied to the fibers in the axial direction.

[0027] In one or more embodiments of the present invention, it is preferable that the polyester-based fibers have a crimped shape 1 satisfying the requirements described in (1) below:

(1) a primary crimp frequency of 5.0 crimps/25 mm or more and 30 crimps/25 mm or less and a secondary crimp frequency of 1.0 crimps/25 mm or more and 4.0 crimps/25 mm or less.

[0028] In one or more embodiments of the present invention, the crimped shape 1 satisfies the requirements (1), thereby enhancing processability in using the polyester-based fibers having the crimp to process the fibers into a pile fabric, specifically processability in a carding machine. The crimped shape 1 has a primary crimp frequency of preferably 5.0 crimps/25 mm or more and 30 crimps/25 mm or less, and more preferably 8.0 crimps/25 mm or more and 15 crimps/25 mm or less. If the primary crimp frequency is less than 5.0 crimps/25 mm, the entanglement between fibers is loose, and the web may be easily cut. On the other hand, the primary crimp frequency is more than 30 crimps/25 mm, the entanglement between fibers is excessively increased, and the processability in a carding machine may be deteriorated, or many neps or slubs may occur. The crimped shape 1 has a secondary crimp frequency of preferably 1.0 crimps/25 mm or more and 4.0 crimps/25 mm or less, and more preferably 1.5 crimps/25 mm or more and 2.5 crimps/25 mm or less. If the secondary crimp frequency is less than 1.0 crimps/25 mm, the entanglement between fibers is loose, and the web may be easily cut. On the other hand, the secondary crimp frequency is more than 4.0 crimps/25 mm, the entanglement between fibers is excessively increased, the processability in a carding machine may be deteriorated, or many neps or slubs may occur.

[0029] In one or more embodiments of the present invention, a crimped shape 2 of the polyester-based fibers has a secondary crimp frequency of preferably 0.0 crimps/25 mm or more and 1.0 crimps/25 mm or less, and more preferably satisfies the requirements described in (2) below:
(2) a primary crimp frequency of 3.0 crimps/25 mm or more and 8.0 crimps/25 mm or less and a secondary crimp frequency of 0.0 crimps/25 mm or more and 1.0 crimps/25 mm or less.

[0030] In one or more embodiments of the present invention, the crimped shape 2 shows a crimp expressed by the polyester-based fibers constituting the pile fabric in processing the polyester-based fibers into the pile fabric. In order for the polyester-based fibers constituting the pile fabric to show an appearance similar to that of natural fur after being processed into the pile fabric, the polyester-based fibers have a crimp preferably satisfying a secondary crimp frequency of 0.0 crimps/25 mm or more and 1.0 crimps/25 mm or less, and more preferably satisfying a primary crimp frequency of 3.0 crimps/25 mm or more and 8.0 crimps/25 mm or less and a secondary crimp frequency of 0.0 crimps/25 mm or more and 1.0 crimps/25 mm or less, after the dry heat treatment. If the polyester-based fibers do not exhibit these crimp characteristics after the dry heat treatment at 150°C for 10 minutes, it may not be possible to show a realistic appearance of the pile fabric constituted by the polyester-based fibers having the crimp.

[0031] In one or more embodiments of the present invention, a primary crimp means the smallest crimp having the smallest period out of crimps of the fibers, and a secondary crimp means a crimp being superimposed on a plurality of primary crimps and having a larger period than the primary crimp. FIG. 1 illustrates an example of a primary crimp and a secondary crimp. As illustrated in FIG. 1, the primary crimp is the smallest crimp having the smallest period out of the crimps of the fibers, and the secondary crimp is a crimp being superimposed on a plurality of primary crimps and having a larger period than the primary crimp.

[0032] In one or more embodiments of the present invention, the primary crimp frequency and the percentage of crimp are measured in accordance with JIS L 1015, and the secondary crimp frequency is a value measured and calculated as below.

<Secondary crimp frequency>

[0033] An unopened portion is taken out from staple fibers. The number of crests a of the secondary crimp and the fiber length b of the unopened portion are measured with no load being applied to the unopened portion. The secondary crimp frequency is calculated by the following formula with the number of samples n = 5 using the number of crests a of the secondary crimp and the fiber length b of the unopened portion. As the unopened portion, one having a fiber length of 50 mm or more is used.

[0034] In one or more embodiments of the present invention, examples of the form of the polyester-based fibers include a filament form, a staple form, and a tow form in which filaments are bundled together, but are not particularly limited to these as long as the polyester-based fibers have a crimp.

[0035] In one or more preferred embodiments of the present invention, the polyester-based fibers have the crimped shape 1 satisfying the requirements (1), and the crimped shape 1 satisfying the requirements (1) is changed into the crimped shape 2 satisfying the requirements (2) by the dry heat treatment at 150°C for 10 minutes. Thus, the polyester-based fibers can express the crimped shape 2 satisfying the requirements (2) in the polishing at a low temperature of 90°C or more and 160°C or less in pile fabric processing. Therefore, it is possible to obtain an appearance similar to that of natural fur, specifically a napped portion having a gentle wavy shape. In the case of polyester-based fibers having a crimp that does not express the crimped shape 2 with the dry heat treatment at 150°C for 10 minutes, the polyester-based fibers are hard to express the crimped shape 2 satisfying the requirements (2) through the polishing at a low temperature of 90°C or more and 160°C or less, and it may be difficult to obtain a napped portion having an appearance similar to that of natural fur.

[0036] In one or more embodiments of the present invention, the percentage of crimp of the polyester-based fibers is not particularly limited, but is preferably, e.g., 5% or more and 25% or less, and more preferably 8% or more and 15% or less, from the viewpoint of enhancing the processability in a carding machine. Moreover, in a case where the polyester-based fibers are subjected to a dry heat treatment at 140°C for 30 minutes, the percentage of crimp is preferably 5% or less, and more preferably 3% or less, from the viewpoint of more easily expressing an appearance similar to that of natural fur through the polishing at a low temperature of 90°C or more and 160°C or less in the pile fabric processing.

[0037] The single fiber fineness of the polyester-based fibers is not particularly limited, but is preferably, e.g., 10 dtex or less, and more preferably 5 dtex or less. If the single fiber fineness is more than 10 dtex, heat tends to be insufficiently transferred in the polishing, and an increase in the number of times of polishing may be required in order to express the crimped shape satisfying the requirements (2). Moreover, the increase in the number of times of polishing may deteriorate soft texture. Furthermore, the single fiber fineness of the polyester-based fibers is not particularly limited, but is preferably, e.g., 1 dtex or more from the viewpoint of handleability of the fibers.

[0038] The cross-sectional shape of the polyester-based fibers is not particularly limited, but is preferably a flat cross-sectional shape having an ellipticity of 1:2 to 1:7, and more preferably a modified flat cross-sectional shape having irregularities in a long side portion of the flat cross-sectional shape, from the viewpoints of the feel and recovering strength of the pile fabric.

[0039] In one or more embodiments of the present invention, it is preferable that the polyester-based fibers are produced by a production method similar to that of usual polyester-based fibers except that the polyester-based fibers are caused to have the crimped shape satisfying the requirements (1) by, in the crimp imparting process 1, imparting the crimped shape satisfying the requirements (2) at a temperature of 130°C or more and 230°C or less on the polyester-based fibers that are not subjected to heat of 150°C or more in the spinning process, and then, in the crimp imparting process 2, crimping the polyester-based fibers at a temperature of 70°C or more and 130°C or less.

[0040] In one or more embodiments of the present invention, the polyester-based fibers can be produced by, e.g., firstly melt kneading, using various general kneading machines, the polyester-based resin or the polyester-based resin composition obtained by dry blending the polyester-based resin and the additive agent, pelletizing the polyester-based resin or the polyester-based resin composition, and then melt spinning the resulting pellets. The melt spinning is performed while the temperatures (spinning temperatures) of, e.g., an extruder, a gear pump, and a spinneret are set at 250°C or more and 300°C or less, and the obtained spun yarns are passed through a heated tube, cooled to a temperature of not more than the glass transition point of the polyester-based resin, and wound up at a speed of 50 m/min or more and 4500 m/min or less to obtain spun yarns (undrawn yarns).

[0041] The spun yarns (undrawn yarns) can be drawn through hot drawing. The heating means for the hot drawing may be a heating roller, a heat plate, a steam jet apparatus, or a hot water bath, and they can be used in combination as appropriate. The drawing temperature is not particularly limited, but may be, e.g., 50°C or more and 95°C or less. The drawn yarns can be subjected to a heat treatment as needed. The heating means for the heat treatment may be a heating roller, a heat plate, a steam jet apparatus, or a hot water bath, and they can be used in combination as appropriate. The draw ratio is not particularly limited, but may be, e.g., 300% or more and 500% or less, and preferably 350% or more and 450% or less, from the viewpoint of the fiber strength. Here, the draw ratio is calculated by the following formula.

[0042] Although the polyester-based fibers that are not subjected to heat of 150°C or more in the spinning process is not particularly limited as long as it is not subjected to heat of 150°C or more, the fibers may be, e.g., undrawn yarns, drawn yarns, or heat treated yarns obtained by subjecting drawn yarns to relaxation heat treatment or stretched heat treatment at less than 150°C, but are preferably drawn yarns or heat treated yarns obtained by subjecting drawn yarns to a heat treatment at less than 150°C from the viewpoint of final mechanical properties of yarns.

[0043] The inventors of the present invention found that in one or more preferred embodiments, the polyester-based fibers constituting the pile fabric had the crimped shape satisfying the requirements (2), thereby expressing an appearance similar to that of natural fur, specifically a gentle wavy shape. Moreover, the inventors found the following. In the crimp imparting process 1, the crimped shape satisfying the requirements (2) was imparted at a temperature of 130°C or more and 230°C or less on the polyester-based fibers that were not subjected to heat of 150°C or more in the spinning process, and thus crystals of the polyester-based fibers memorized the crimped shape. Then, in order to enhance the processability in a carding machine, in the crimp imparting process 2, a crimp with a different shape was imparted on the polyester-based fibers to express the crimped shape satisfying the requirements (1), and thus the crimped shape satisfying the requirements (2) was seemingly lost. However, the crimped shape satisfying the requirements (2) was restored by the dry heat treatment at 150°C for 10 minutes. In addition, when the polyester-based fibers having the crimped shape 1 satisfying the requirements (1) are used as a raw material for the pile fabric, the crimped shape of the polyester-based fibers is changed in the polishing at a relatively low temperature of 90°C or more and 160°C or less in the pile fabric processing, and the crimped shape satisfying the requirements (2) is expressed. Thus, it is possible to obtain an appearance similar to that of natural fur, specifically a napped portion in which a gentle wavy shape is left.

[0044] In the crimp imparting process 1 and the crimp imparting process 2, a known crimp imparting apparatus such as a gear crimper, an embossed roll, and a stuffing box crimper may be used as long as it is possible to impart the crimp characteristics described above on the polyester-based fibers. From the viewpoint of easily imparting the crimped shape satisfying the requirements (2), it is preferable that the crimp imparting process 1 is performed by one or more selected from the group consisting of a gear crimper and an embossed roll. Moreover, from the viewpoint of ensuring the processability in a carding machine, it is preferable that the crimp imparting process 2 is performed by a mechanical stuff crimping. The mechanical stuff crimping can be performed by, e.g., a stuffing box crimper.

[0045] In one or more embodiments of the present invention, a pile fabric includes the polyester-based fibers in a pile portion. The polyester-based fibers have a crimp having a primary crimp frequency of 3.0 crimps/25 mm or more and 8.0 crimps/25 mm or less and a secondary crimp frequency of 0.0 crimps/25 mm or more and 1.0 crimps/25 mm or less. In the present invention, the pile portion refers to a napped portion of the pile fabric other than a base fabric (also referred to as a "ground structure") portion. From the viewpoint of the appearance, the pile fabric includes the polyester-based fibers preferably in an amount of 30% by weight or more, more preferably in an amount of 40% by weight or more, and further preferably in an amount of 50% by weight or more with respect to the pile portion as a whole. Hereinafter, fibers constituting the pile portion are also referred to as pile fibers.

[0046] From the viewpoint of achieving a two-layer structure closely resembling natural fur, the pile fabric preferably includes a long pile portion and a short pile portion that have different pile lengths, and the difference between the average pile length of the long pile portion and the average pile length of the short pile portion is preferably 2 mm or more, and more preferably 5 mm or more and 50 mm or less. In the present invention, the average pile length is determined by vertically standing fibers constituting the pile portion of the pile fabric such that the fibers are aligned, measuring the length from the roots of the fibers constituting the pile portion (roots on a surface of the pile fabric) to the tip of the pile at 10 sections in each pile portion, and averaging the measured lengths.

[0047] In order to express a realistic appearance, the polyester-based fibers are preferably included in the short pile portion of the pile fabric, and are more preferably included in an amount of 50% by weight or more in the short pile portion.

[0048] The pile portion may also include other fibers such as, e.g., modacrylic fibers or polyvinyl chloride-based fibers in addition to the polyester-based fibers. From the viewpoint of obtaining soft texture, the long pile portion preferably includes modacrylic fibers constituted by an acrylic-based copolymer containing acrylonitrile in an amount of 35% by weight or more and less than 95% by weight. A pile fabric having extremely good texture as well as good recovering strength and voluminousness can be provided by the polyester-based fibers being used in combination with the modacrylic fibers. The acrylic-based copolymer preferably contains another monomer that is copolymerizable with acrylonitrile in an amount of more than 5% by weight and 65% by weight or less, in addition to acrylonitrile. As the other monomer, though it is not particularly limited, it is preferable to use e.g., at least one monomer selected from the group consisting of vinyl halides, vinylidene halides, and metal salts of sulfonic acid-containing monomers, and it is more preferable to use at least one monomer selected from the group consisting of vinyl chloride, vinylidene chloride, and sodium styrenesulfonate.

[0049] In one or more embodiments of the present invention, the pile fabric can be produced by using the polyester-based fibers (preferably having the crimped shape 1 satisfying the requirements (1)) as pile fibers, and performing the polishing at a temperature of 90°C or more and 160°C or less. In the obtained pile fabric, because the polyester-based fibers have a crimp having a secondary crimp frequency of 0.0 crimps/25 mm or more and 1.0 crimps/25 mm or less, and preferably express the crimped shape satisfying the requirements (2), the napped portion has an appearance similar to that of natural fur, specifically a gentle wavy shape.

[0050] In one or more embodiments of the present invention, it is possible to perform manufacturing a pile fabric by producing a pile fabric including the polyester-based fibers in an amount of 30% by weight or more in a pile portion as a whole. Preferably, the polyester-based fibers are polished at a temperature of 90°C or more and 160°C or less. In one or more preferred embodiments of the present invention, the pile fabric can be produced by a manufacturing method that is similar to that for a usual pile fabric, except for using at least the polyester-based fibers as pile fibers and performing the polishing at a temperature of 90°C or more and 160°C or less. For example, the polyester-based fibers (having the crimped shape 1 satisfying the requirements (1)) are passed through a carding machine such as a roller carding machine to produce a sliver. The obtained sliver is knitted into a pile fabric by a sliver knitting machine. Pre-polishing and pre-shearing are performed at a temperature of 90°C or more and 160°C or less, then polishing is performed at a temperature of 90°C or more and 160°C or less, and then shearing is performed. The crimped shape of the polyester-based fibers is changed, specifically the crimped shape satisfying the requirements (1) is changed, and the crimped shape satisfying the requirements (2) is expressed by performing the polishing at a temperature of 90°C or more and 160°C or less. The polishing may also be performed multiple times at different temperatures. Moreover, a back surface (opposite side of the napped portion) of the pile fabric may be coated with a backing resin before the polishing in order to eliminate or reduce pile fiber loss and for tentering. As the backing resin, it is possible to use an acrylic acid ester-based adhesive or polyurethane-based adhesive.

Examples

[0051] Hereinafter, one or more embodiments of the present invention will be specifically described by way of examples and comparative examples. Note that the present invention is not limited to these examples.

[0052] First, a measuring method and an evaluation method used in examples and comparative examples will be described.

(Primary crimp frequency and percentage of crimp)

[0053] The primary crimp frequency and percentage of crimp were measured in accordance with JIS L 1015.

(Secondary crimp frequency)

[0054] An unopened portion was taken out from staple fibers. The number of crests a of the secondary crimp and the fiber length b of the unopened portion were measured with no load being applied to the unopened portion. The secondary crimp frequency was calculated by the following formula with the number of samples n = 5 using the number of crests a of the secondary crimp and the fiber length b of the unopened portion. As the unopened portion, one having a fiber length of 50 mm or more was used.

(Processability in carding machine)

[0055] In a case where no problem occurred in carding in a stage of processing into a pile fabric, processability in a carding machine was determined to be good; otherwise, processability in a carding machine was determined to be poor.

(Appearance evaluation)

[0056] The appearance of a pile fabric was evaluated in accordance with the following criteria. In a case where pile fibers in a napped portion of the pile fabric had an appearance similar to that of natural fur, specifically a crimped shape closely resembling that of natural fox fur shown in FIG. 2, the appearance was determined to be good; otherwise, the appearance was determined to be poor. Concerning a pile in which plural types of fibers were used, e.g., a step pile, only a portion of the pile in which polyester fibers having a crimp were used was evaluated in accordance with the above criteria.

(Example 1)

<Production of polyester-based fibers>

[0057] Spinning was performed by a usual spinning machine at a spinning temperature of 290°C and a speed of 320 m/min using polyethylene terephthalate (PET) having an intrinsic viscosity (IV value) of 0.65 and a spinneret with 48 holes having a diameter of 0.4 mm and a circular cross-section. The obtained undrawn yarns were drawn by 375% by a hot roller at 80°C to obtain drawn yarns. Titanium oxide had been added to PET as a delustering agent in an amount of 0.3 parts by weight with respect to 100 parts by weight of PET. Thereafter, after the drawn yarns were assembled to an appropriate fineness, a crimped shape exhibiting crimp characteristics shown in Table 1 below was imparted on the yarns by a gear crimper heated to 155°C (crimp imparting process 1), then the yarns were crimped through preheating at 98°C by a stuffing box crimper, and thus crimped PET fibers that had a crimped shape exhibiting crimp characteristics shown in Table 1 below (crimp imparting process 2) and had a single fiber fineness of 3 dtex were obtained.

<Production of pile fabric>

[0058] The obtained crimped PET fibers were cut to 51 mm to obtain staple fibers for a pile fabric. A sliver was produced by passing 100% by weight of the staple fibers through a roller carding machine. A pile fabric was produced by a sliver knitting machine. Then, pre-polishing and pre-shearing were performed at 120°C to trim a napped portion of the pile fabric to a length of 18 mm, then a back surface of the fabric was back-coated with an acrylic acid ester-based adhesive, and then a tentering treatment was performed. Then, polishing was performed at 160°C three times, at 130°C three times, and at 100°C three times. Thereafter, the napped portion was trimmed through shearing to a length of 20 mm, and thus a pile fabric having a basis weight of about 800 g/m² was obtained.

(Example 2)

<Production of polyester-based fibers>

[0059] Spinning was performed by a usual spinning machine at a spinning temperature of 270°C and a speed of 400 m/min using polyethylene terephthalate (PET) having an intrinsic viscosity (IV value) of 0.65 and a spinneret with 200 holes having a diameter of 0.3 mm and a flat cross-sectional shape. The obtained undrawn yarns were drawn by 310% by a hot roller at 80°C to obtain drawn yarns. Titanium oxide had been added to PET as a delustering agent in an amount of 0.3 parts by weight with respect to 100 parts by weight of PET. Thereafter, after the drawn yarns were assembled to an appropriate fineness, a crimped shape exhibiting crimp characteristics shown in Table 1 below was imparted on the yarns by an embossed roll heated to 180°C (crimp imparting process 1), then the yarns were crimped through preheating at 98°C by a stuffing box crimper, and thus crimped PET fibers that had a crimped shape exhibiting crimp characteristics shown in Table 1 below (crimp imparting process 2) and had a single fiber fineness of 3 dtex were obtained.

<Production of pile fabric>

[0060] A pile fabric was produced in the same manner as in Example 1, except that the obtained crimped PET fibers were used.

(Example 3)

<Production of polyester-based fibers>

[0061] Spinning was performed by a usual spinning machine at a spinning temperature of 270°C and a speed of 400 m/min using polyethylene terephthalate (PET) having an intrinsic viscosity (IV value) of 0.65 and a spinneret with 200 holes having a diameter of 0.3 mm and a flat cross-sectional shape. The obtained undrawn yarns were drawn by 310% by a hot roller at 80°C to obtain drawn yarns. Titanium oxide had been added to PET as a delustering agent in an amount of 0.3 parts by weight with respect to 100 parts by weight of PET. Thereafter, after the drawn yarns were assembled to an appropriate fineness, a crimped shape exhibiting crimp characteristics shown in Table 1 below was imparted on the yarns by an embossed roll heated to 180°C (crimp imparting process 1), then the yarns were crimped through preheating at 98°C by a stuffing box crimper, and thus crimped PET fibers that had a crimped shape exhibiting crimp characteristics shown in Table 1 below (crimp imparting process 2) and had a single fiber fineness of 3 dtex were obtained.

<Production of pile fabric>

[0062] A pile fabric was produced in the same manner as in Example 1, except that the obtained crimped PET fibers were used.

(Example 4)

<Production of polyester-based fibers>

[0063] Crimped PET fibers were produced in the same manner as in Example 3.

<Production of pile fabric>

[0064] The obtained crimped PET fibers were cut to 51 mm to obtain staple fibers for a pile fabric. A sliver was produced by mixing 50 parts by weight of the staple fibers with 30 parts by weight of modacrylic fibers (resin composition: 50 parts by weight of acrylonitrile, 49.5 parts by weight of vinyl chloride, 0.5 parts by weight of styrenesulfonic acid) having a single fiber fineness of 27 dtex and a cut length of 102 mm and 20 parts by weight of the modacrylic fibers having a single fiber fineness of 12 dtex and a cut length of 78 mm, and passing the mixture through a roller carding machine. A pile fabric was produced by a sliver knitting machine. Then, pre-polishing was performed at 120°C, a back surface of the fabric was back-coated with an acrylic acid ester-based adhesive, and then a tentering treatment was performed. Then, polishing was performed at 160°C three times, at 130°C three times, and at 100°C three times. Thus, a step pile fabric having a basis weight of about 1100 g/m² was obtained.

(Comparative example 1)

<Production of polyester-based fibers>

[0065] Crimped PET fibers having a single fiber fineness of 3 dtex were obtained in the same manner as in Example 1, except that drawn yarns were heat treated in a uniform hot-air dryer set at 180°C for one minute, after the drawn yarns were assembled to an appropriate fineness, the yarns were crimped through preheating at 98°C by a stuffing box crimper, and a heat treatment was not performed after the yarns were crimped.

<Production of pile fabric>

[0066] A pile fabric was produced in the same manner as in Example 1, except that the obtained crimped PET fibers were used.

(Comparative example 2)

<Production of polyester-based fibers>

[0067] Spinning was performed by a usual spinning machine at a spinning temperature of 270°C and a speed of 400 m/min using polyethylene terephthalate (PET) having an intrinsic viscosity (IV value) of 0.65 and a spinneret with 200 holes having a diameter of 0.3 mm and a flat cross-sectional shape. The obtained undrawn yarns were drawn by 310% by a hot roller at 80°C to obtain drawn yarns. Titanium oxide had been added to PET as a delustering agent in an amount of 0.3 parts by weight with respect to 100 parts by weight of PET. Thereafter, after the drawn yarns were assembled to an appropriate fineness, a crimped shape exhibiting crimp characteristics shown in Table 1 below was imparted on the yarns by an embossed roll heated to 180°C (crimp imparting process 1), and thus crimped PET fibers having a single fiber fineness of 3 dtex were obtained.

<Production of pile fabric>

[0068] The obtained crimped PET fibers were cut to 51 mm to obtain staple fibers for a pile fabric. An attempt was made to produce a sliver by passing 100% by weight of the staple fibers through a roller carding machine, but the entanglement between the fibers was loose, and a sliver was not able to be produced.

(Comparative example 3)

<Production of polyester-based fibers>

[0069] Spinning was performed by a usual spinning machine at a spinning temperature of 270°C and a speed of 400 m/min using polyethylene terephthalate (PET) having an intrinsic viscosity (IV value) of 0.65 and a spinneret with 200 holes having a diameter of 0.3 mm and a flat cross-sectional shape. The obtained undrawn yarns were drawn by 310% by a hot roller at 80°C to obtain drawn yarns. Titanium oxide had been added to PET as a delustering agent in an amount of 0.3 parts by weight with respect to 100 parts by weight of PET. Thereafter, after the drawn yarns were assembled to an appropriate fineness, a crimped shape exhibiting crimp characteristics shown in Table 1 below was imparted on the yarns by an embossed roll heated to 180°C (crimp imparting process 1), and thus crimped PET fibers having a single fiber fineness of 3 dtex were obtained.

<Production of pile fabric>

[0070] The obtained crimped PET fibers were cut to 51 mm to obtain staple fibers for a pile fabric. An attempt was made to produce a sliver by passing 100% by weight of the staple fibers through a roller carding machine, but the entanglement between the fibers was loose, and a sliver was not able to be produced.

(Comparative example 4)

<Production of polyester-based fibers>

[0071] Spinning was performed by a usual spinning machine at a spinning temperature of 270°C and a speed of 400 m/min using polyethylene terephthalate (PET) having an intrinsic viscosity (IV value) of 0.65 and a spinneret with 200 holes having a diameter of 0.3 mm and a flat cross-sectional shape. Then, the obtained undrawn yarns were drawn by 310% by a hot roller at 80°C to obtain drawn yarns. Titanium oxide had been added to PET as a delustering agent in an amount of 0.3 parts by weight with respect to 100 parts by weight of PET. Thereafter, after the drawn yarns were assembled to an appropriate fineness, a crimped shape exhibiting crimp characteristics shown in Table 1 below was imparted on the yarns by an embossed roll heated to 180°C (crimp imparting process 1), and thus crimped PET fibers having a single fiber fineness of 3 dtex were obtained.

<Production of pile fabric>

[0072] The obtained crimped PET fibers were cut to 51 mm to obtain staple fibers for a pile fabric. An attempt was made to produce a sliver by passing 100% by weight of the staple fibers through a roller carding machine, but the entanglement between the fibers was loose, and a sliver was not able to be produced.

[0073] The primary crimp frequency, percentage of crimp, and secondary crimp frequency of the polyester-based fibers in Examples 1-4 and Comparative examples 1-4 were measured as described above. Moreover, after the crimped PET fibers obtained in Examples 1-4 and Comparative examples 1-4 were subjected to a dry heat treatment at 150°C for 10 minutes, specifically after the crimped PET fibers were allowed to stand still in a hot-air convection dryer set at 150°C for 10 minutes, the primary crimp frequency, percentage of crimp, and secondary crimp frequency of the crimped PET fibers after the dry heat treatment were measured as described above. Furthermore, the appearance of the pile fabric obtained in Examples 1-4 and Comparative example 1 was evaluated as described above. Table 1 below indicates these results.

[Table 1]

	After crimp imparting process 1				After crimp imparting process 2				After dry heat treatment			Production of pile fabric
	Crimp imparting temperature (°C)	Primary crimp frequency (crimps/25mm)	Percentage of crimp (%)	Secondary crimp frequency (crimps/25mm)	Crimp imparting temperature (°C)	Primary crimp frequency (crimps/25mm)	Percentage of crimp (%)	Secondary crimp frequency (crimps/25mm)	Primary crimp frequency (crimps/25mm)	Percentage of crimp (%)	Secondary crimp frequency (crimps/25mm)	Processability in carding machine	Appearance evaluation
Example 1	155	5.7	3.6	0.0	100	11.0	7.3	2.2 5.7		4.0	0.0	Good	Good
Example 2	180	3.8	3.1	0.0	100	11.8	10.5	2.2	4.0	3.5	0.4	Good	Good
Example 3	180	7.2	3.5	0.0	100	13.5	8.3	2.4	7.3	3.8	0.0	Good	Good
Example 4	180	7.2	3.5	0.0	100	13.5	8.3	2.4	7.3	3.8	0.0	Good	Good
Comparative example 1	180*	0.0	0.0	0.0	100	12.5	10.1	2.4	0.0	0.0	0.0	Good	Poor
Comparative example 2	155	5.7	3.6	0.0	Crimp imparting process 2 was not performed				5.7	3.6	0.0	Poor	Production impossible
Comparative example 3	180	3.8	3.1	0.0	Crimp imparting process 2 was not performed				3.8	3.1	0.0	Poor	Production impossible
Comparative example 4	180	7.2	3.5	0.0	Crimp imparting process 2 was not performed				7.2	3.5	0.0	Poor	Production impossible

*: In Comparative example 1, after stretched heat treatment was performed at 180°C, the fibers were crimped by a mechanical stuff crimping.

[0074] As understood from Table 1, in cases where the polyester-based fibers of Examples 1-4 having a crimp that had the crimped shape satisfying the requirements (1) and expressed a crimped shape satisfying the requirements (2) with the dry heat treatment at 150°C for 10 minutes were used, the processability in a carding machine was good, and the crimp similar to that of natural fur was able to be left in a napped surface layer portion of the pile fabric by the polishing at a relatively low temperature of 90°C or more and 160°C or less. In the examples, the polyester-based fibers having the crimped shape satisfying the requirements (1) were able to be obtained by, in the crimp imparting process 1, imparting the crimped shape satisfying the requirements (2) at a temperature of 130°C or more and 230°C or less on the polyester-based fibers that were not subjected to heat of 150°C or more in the spinning process before crimping, and then, in the crimp imparting process 2, crimping the polyester-based fibers at a temperature of 70°C or more and 130°C or less. In the cases where the polyester-based fibers were subjected to the dry heat treatment at 150°C for 10 minutes, the crimped shape satisfying the requirements (2) was expressed.

[0075] On the other hand, in a case where the polyester-based fibers of Comparative example 1 that had the crimped shape satisfying the requirements (1) but did not express a crimped shape satisfying the requirements (2) with the dry heat treatment at 150°C for 10 minutes were used, the processability in a carding machine was good, but a crimp similar to that of natural fur was not able to be left in a napped surface layer portion of the pile fabric by the polishing at a relatively low temperature of 90°C or more and 160°C or less. Moreover, concerning the polyester-based fibers of Comparative examples 2-4 having a crimp that had the crimped shape satisfying the requirements (2) and being not changed by the dry heat treatment at 150°C for 10 minutes, the processability in a carding machine was poor, and a pile fabric was not able to be produced.

Claims

1. A polyester-based fiber, comprising a crimp with a crimped shape to be changed by a dry heat treatment at 150°C for 10 minutes.

2. The polyester-based fiber according to claim 1,
wherein the polyester-based fiber comprises a crimp satisfying requirements described in (1) below before the dry heat treatment and comprises a crimp having a secondary crimp frequency of 0.0 crimps/25 mm or more and 1.0 crimps/25 mm or less after the dry heat treatment:

(1) a primary crimp frequency of 5.0 crimps/25 mm or more and 30 crimps/25 mm or less and a secondary crimp frequency of 1.0 crimps/25 mm or more and 4.0 crimps/25 mm or less.

3. The polyester-based fiber according to claim 2, wherein the polyester-based fiber comprises a crimp satisfying requirements described in (2) below after the dry heat treatment:
(2) a primary crimp frequency of 3.0 crimps/25 mm or more and 8.0 crimps/25 mm or less and a secondary crimp frequency of 0.0 crimps/25 mm or more and 1.0 crimps/25 mm or less.

4. The polyester-based fiber according to any one of claims 1 to 3, wherein the polyester-based fiber has a single fiber fineness of 1 dtex or more and 10 dtex or less.

5. A method for manufacturing a polyester-based fiber, comprising:

in a crimp imparting process 1, imparting a crimp satisfying requirements described in (2) below at a temperature of 130°C or more and 230°C or less on a polyester-based fiber that is not subjected to heat of 150°C or more in a spinning process before crimping; and

then, in a crimp imparting process 2, crimping the polyester-based fiber at a temperature of 70°C or more and 130°C or less,

to obtain a polyester-based fiber comprising a crimp satisfying requirements described in (1) below:

(1) a primary crimp frequency of 5.0 crimps/25 mm or more and 30 crimps/25 mm or less and a secondary crimp frequency of 1.0 crimps/25 mm or more and 4.0 crimps/25 mm or less; and

(2) a primary crimp frequency of 3.0 crimps/25 mm or more and 8 crimps/25 mm or less and a secondary crimp frequency of 0.0 crimps/25 mm or more and 1.0 crimps/25 mm or less.

6. The method according to claim 5, wherein the crimp imparting process 1 is performed by one or more selected from the group consisting of a gear crimper and an embossed roll.

7. The method according to claim 5 or 6, wherein the crimp imparting process 2 is performed by a mechanical stuff crimping.

8. A method for manufacturing a pile fabric, comprising producing a pile fabric comprising the polyester-based fiber according to any one of claims 1 to 4 in an amount of 30% by weight or more in a pile portion as a whole.

9. The method according to claim 8, wherein the polyester-based fiber is polished at a temperature of 90°C or more and 160°C or less.

10. The method according to claim 8 or 9,

wherein the pile fabric comprises a long pile portion and a short pile portion, and

a difference between an average pile length of the long pile portion and an average pile length of the short pile portion is 2 mm or more.

11. The method according to claim 10, wherein the short pile portion comprises the polyester-based fiber.

12. The method according to claim 10 or 11, wherein the long pile portion comprises a modacrylic fiber constituted by an acrylic-based copolymer comprising acrylonitrile in an amount of 35% by weight or more and less than 95% by weight.

13. A pile fabric, comprising the polyester-based fiber according to claim 1 in an amount of 30% by weight or more with respect to a pile portion as a whole,
wherein the polyester-based fiber comprises a crimp having a primary crimp frequency of 3.0 crimps/25 mm or more and 8.0 crimps/25 mm or less and a secondary crimp frequency of 0.0 crimps/25 mm or more and 1.0 crimps/25 mm or less.

Drawing