JP2019019442A - Crimped fiber and production method of crimped fiber - Google Patents

Abstract

To provide a crimped fiber having high crimp property and a production method of the crimped fiber.SOLUTION: The crimped fiber contains a polypropylene-based resin composition containing 30 mass% or over and 99 mass% or under of a propylene homopolymer (A) having a melting point (Tm-D) measured by using a differential scanning calorimeter (DSC) of exceeding 120°C and 1 mass% or over and 70 mass% or under of a propylene-based resin (B) having a fusion endotherm (ΔH-D) of 0 J/g or over and 80 J/g or under, obtained by a fusion endothermic curve obtained by keeping a sample in a nitrogen atmosphere at -10°C for 5 minutes, followed by rising the temperature at a rate of 10°C/min by using a differential scanning calorimeter (DSC), and is characterized by that its tensile strength measured in accordance of JIS L1013 (2010) is 1.5 cN/Dtex or over, and its crimped ratio becomes 30% or over by heat treatment at a temperature of 120°C for 15 minutes.SELECTED DRAWING: None

Description

  The present invention relates to a crimped fiber and a method for producing a crimped fiber.

Polypropylene resins are widely used in fiber applications because they are inexpensive and have relatively good mechanical properties and spinnability.
For example, in Patent Document 1, by using a polypropylene resin having a specific crystallinity distribution, the molecular weight of the resin that affects the mechanical properties, the spinning temperature that affects the productivity, and the discharge amount can be changed more. It is disclosed to provide a polypropylene resin capable of high speed spinning. Patent Document 2 discloses a method for producing a polypropylene elastic fiber having excellent elastic recovery, high strength, no stickiness and good texture by using a specific low crystalline polypropylene as a raw material, and excellent It is disclosed to provide a polypropylene-based elastic fiber having elastic recoverability. Further, a composite fiber comprising a first component and a second component, wherein the first component occupies at least 20% of the surface of the composite fiber when the composite fiber is viewed from a cross section, and the center of gravity of the second component Latent crimped conjugate fiber that is an eccentric core-sheath type fiber cross section whose position is deviated from the center of gravity of the conjugate fiber, or a polypropylene-based latent crimped processed yarn made of polypropylene-based multifilaments that satisfies a specific condition Is known (for example, Patent Documents 3 and 4).

International Publication No. 2006/051708 International Publication No. 2010/018789 JP 2012-158861 A JP 2003-313736 A

  As a means for imparting crimpability to a fiber, a method of subjecting the fiber to heat shrinkage is known. However, as in Patent Document 1, only using a polypropylene resin having a specific crystallinity distribution did not exhibit crimpability. Further, the fiber described in Patent Document 2 is not a crimped fiber shape, but is based on the elastic recoverability of the resin itself, and its manufacturing method is not practical. In the fibers described in Patent Documents 3 and 4, there is a case where the degree of crimp is low or the crimpability is difficult to control even when the heat shrink treatment is performed.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a crimped fiber having high crimpability and a method for producing the crimped fiber.

  As a result of intensive studies to solve the above problems, the present inventors have found that the problems can be solved by the following invention.

That is, the present disclosure relates to the following.
[1] Propylene homopolymer (A) having a melting point (Tm-D) measured by a differential scanning calorimeter (DSC) of more than 120 ° C of 30% by mass to 99% by mass, and a differential scanning calorimeter (DSC) The melting endotherm (ΔH-D) obtained from a melting endotherm curve obtained by holding the sample at −10 ° C. for 5 minutes under a nitrogen atmosphere and raising the temperature at 10 ° C./min is 0 J / g. Including a polypropylene resin composition containing 1% by mass or more and 70% by mass or less of a propylene resin (B) that is 80 J / g or less, and a tensile strength in accordance with JIS L1013 (2010) is 1.5 cN / Dtex or more A crimped fiber having a crimp rate of 30% or more by heat treatment at 120 ° C. for 15 minutes.
[2] The crimped fiber according to the above [1], wherein the crystallization time of the propylene-based resin (B) exceeds 15 seconds.
[3] The melt flow rate (MFR) measured under the conditions of a temperature of 230 ° C. and a load of 2.16 kg in accordance with JIS K7210 of the propylene homopolymer (A) is 0.1 g / 10 min to 1,000 g / 10 min. The crimped fiber according to the above [1] or [2].
[4] The crimped fiber according to any one of [1] to [3], wherein the propylene-based resin (B) has a weight average molecular weight (Mw) of 10,000 or more and 300,000 or less.
[5] Any of [1] to [4] above, wherein the propylene resin (B) has a melting point (Tm-D) measured by a differential scanning calorimeter (DSC) of 40 ° C. or higher and 120 ° C. or lower. A crimped fiber according to 1.
[6] The crimped fiber according to any one of [1] to [5], wherein the crimped fiber is a side-by-side fiber or an eccentric core-sheath fiber.
[7] The crimped fiber according to [6], wherein the crimped fiber is an eccentric core-sheath fiber.
[8] The crimped fiber according to [7], in which the mass ratio of the core component to the sheath component is 10/90 to 90/10 in the eccentric core-sheath fiber.
[9] A method for producing a crimped fiber according to any one of [1] to [8], wherein the raw material containing the polypropylene resin composition is melt-spun and the resulting fiber is drawn. A method for producing crimped fibers.
[10] The method for producing a crimped fiber according to the above [9], wherein the final draw ratio is 2 times or more and 8 times or less.
[11] The above-mentioned [9], wherein the stretching step includes a step (1) of winding the obtained fiber once and a step (2) of stretching the fiber wound in the step (1). Or the manufacturing method of the crimped fiber as described in [10].
[12] The method for producing a crimped fiber according to [11], wherein the stretching in the step (2) is performed without heating.
[13] The crimp according to any one of [9] to [12], wherein the melt spinning is a method of manufacturing using a multifilament manufacturing facility having a nozzle having a plurality of holes and a winder. A method for producing fibers.

  According to the present invention, a crimped fiber having high crimpability and a method for producing the crimped fiber can be provided.

It is the electron micrograph (magnification: 200 times) image | photographed after the heat processing of the eccentric core-sheath type | mold crimp fiber of Example 10. FIG. It is an optical microscope photograph (magnification: 50 times) photographed after the heat treatment of the eccentric core-sheath type crimped fiber of Example 10.

Hereinafter, the present invention will be described in detail.
<Crimped fiber>
The crimped fiber of the present embodiment has a propylene homopolymer (A) having a melting point (Tm-D) measured by a differential scanning calorimeter (DSC) of more than 120 ° C. of 30% by mass to 99% by mass, and a differential. Using a scanning calorimeter (DSC), the sample was held at −10 ° C. for 5 minutes in a nitrogen atmosphere, and then heated at a rate of 10 ° C./minute, and then the melting endotherm (ΔH− D) includes a polypropylene resin composition containing 1% by mass to 70% by mass of a propylene resin (B) having a value of 0 J / g or more and 80 J / g or less, and has a tensile strength of 1 according to JIS L1013 (2010). .5 cN / Dtex or more, and the crimping rate becomes 30% or more by heat treatment at 120 ° C. for 15 minutes.

  Here, in this specification, “crimped fiber” is used to include a composite spun fiber formed by a side-by-side type nozzle, an eccentric core-sheath type nozzle, a modified nozzle, or a divided nozzle in which different thermoplastic resins are combined. The core-sheath fiber refers to a fiber whose cross section is composed of a “core” of the inner layer portion and a “sheath” of the outer layer portion, and the eccentric core-sheath fiber is the center of gravity position of the inner layer portion in the cross-sectional shape. Means a fiber different from the center of gravity of the entire fiber.

When the crimped fiber of the present embodiment is an eccentric core-sheath fiber, the propylene-based resin (B) is used for either the component used for the core portion or the component used for the sheath portion. Moreover, when the crimp fiber of this embodiment is a side-by-side type fiber which consists of X component and Y component, the said propylene-type resin (B) is used for either X component or Y component. Thus, by using the propylene-based resin (B) as one component of the crimped fiber of the present embodiment, the crimp rate after heat treatment at a temperature of 120 ° C. for 15 minutes can be 30% or more. And a crimped fiber having high crimpability can be obtained.
In the present specification, of the two components constituting the crimped fiber of the present embodiment, the component in which the propylene resin (B) is used is referred to as a first component, and the other component is referred to as a second component. There is.

[Polypropylene resin composition]
The polypropylene resin composition used in the crimped fiber of this embodiment contains the propylene homopolymer (A) and the propylene resin (B).
As for the said propylene homopolymer (A), melting | fusing point (Tm-D) measured by a differential scanning calorimeter (DSC) exceeds 120 degreeC. If melting | fusing point (Tm-D) is 120 degrees C or less, there exists a possibility that the heat resistance and mechanical strength of a resin composition may become inadequate. From such a viewpoint, the melting point (Tm-D) of the propylene homopolymer (A) is preferably 130 ° C. or higher, more preferably 150 ° C. or higher. Although the upper limit of this melting | fusing point (Tm-D) is not specifically limited, It is preferable that it is 300 degrees C or less.
In the present embodiment, a differential scanning calorimeter (manufactured by Perkin Elmer, “DSC-7”) was used, and 10 mg of the sample was held at −10 ° C. for 5 minutes in a nitrogen atmosphere, and then increased at 10 ° C./min. The peak top of the peak observed on the highest temperature side of the melting endothermic curve obtained by heating is defined as the melting point (Tm-D).

The melt flow rate (MFR) of the propylene homopolymer (A) is preferably 0.1 g / 10 min or more, more preferably 1.0 g / 10 min or more, still more preferably from the viewpoint of easy fiberization. Is 5.0 g / 10 min or more, and from the viewpoint of fiber strength, it is preferably 1,000 g / 10 min or less, more preferably 200 g / 10 min or less, and still more preferably 100 g / 10 min or less.
The melt flow rate (MFR) is measured by a measurement method defined in JIS K7210, and is measured under conditions of a temperature of 230 ° C. and a load of 2.16 kg.

  Content of the propylene homopolymer (A) contained in the said polypropylene resin composition is 30 mass% or more and 99 mass% or less. When it is less than 30% by mass, heat resistance and strength are insufficient. From such a viewpoint, the content of the propylene homopolymer (A) is preferably 50% by mass or more, more preferably 70% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass. It is as follows.

The propylene-based resin (B) is a melting endotherm obtained by using a differential scanning calorimeter (DSC) and holding the sample at −10 ° C. for 5 minutes in a nitrogen atmosphere and then raising the temperature at 10 ° C./min. The melting endotherm (ΔH−D) obtained from the curve is 0 J / g or more and 80 J / g or less. If the melting endotherm (ΔH-D) exceeds 80 J / g, the crimpability is insufficient or the stretchability is lowered. Further, from the viewpoint of further improving the spinnability, stretchability and crimpability of the fiber and further suppressing stickiness, the melting endotherm (ΔHD) is preferably 3 J / g or more, more preferably 10 J / g or more, More preferably, it is 30 J / g or more, and preferably 70 J / g or less, more preferably 60 J / g or less, still more preferably 50 J / g or less.
In this embodiment, the melting endotherm (ΔH-D) is determined by using a differential scanning calorimeter (DSC), holding the sample at −10 ° C. for 5 minutes in a nitrogen atmosphere, and then increasing the temperature at 10 ° C./min. Obtain the area surrounded by the line containing the peak of the melting endotherm curve obtained by the process, the line on the low temperature side without any change in calorie, and the line on the high temperature side without any change in calorie (referred to as the base line) It is calculated by.

The half crystallization time of the propylene-based resin (B) is preferably more than 15 seconds, more preferably 30 seconds or more, still more preferably 150 seconds or more, and preferably 30 minutes or less, more preferably 15 minutes. Hereinafter, it is more preferably 10 minutes or less. When the half crystallization time is within the above range, wrapping and the like are further suppressed in the spinning process, and fiberization becomes easier.
In the present embodiment, the “half crystallization time” refers to that measured by the following measurement method.

<Measuring method of semi-crystallization time>
Using a differential scanning calorimeter (DSC) (manufactured by Perkin Elmer, trade name: “DSC-7”), the measurement is performed by the following method.
(1) Hold 10 mg of sample at 25 ° C. for 5 minutes, raise the temperature to 320 ° C. at 320 ° C./second and hold for 5 minutes. By cooling to 25 ° C. at 320 ° C./second and holding for 300 minutes, the time change of the calorific value in the isothermal crystallization process is measured.
(2) When the integrated value of the calorific value from the start of isothermal crystallization to the completion of crystallization is 100%, the time from the start of isothermal crystallization until the integrated value of the calorific value becomes 50% is semi-crystallized. Define as time.

Using the differential scanning calorimeter (DSC) of the propylene-based resin (B), the highest end of the melting endotherm curve obtained by holding at −10 ° C. for 5 minutes in a nitrogen atmosphere and then raising the temperature at 10 ° C./min. The melting point (Tm-D) defined as the peak top of the peak observed on the side is preferably 40 ° C. or higher, more preferably 60 ° C. or higher, still more preferably 80 ° C. or higher, and preferably 120 ° C. or lower. More preferably, it is 110 degrees C or less, More preferably, it is 100 degrees C or less. If it is 40 degreeC or more, the heat resistance of a fiber will improve more, and if it is 120 degrees C or less, crimpability will improve more.
The melting point can be controlled by appropriately adjusting the monomer concentration and reaction pressure.

  The weight average molecular weight (Mw) of the propylene-based resin (B) is preferably 10,000 or more, more preferably 25,000 or more, still more preferably 40,000 or more, from the viewpoint of the physical properties of the fiber. Preferably it is 300,000 or less, More preferably, it is 200,000 or less, More preferably, it is 150,000 or less.

  In addition, the molecular weight distribution (Mw / Mn) of the propylene resin (B) is preferably 1.5 or more, and preferably 3.0 or less, more preferably 2.5 from the viewpoint of spin drawability. It is as follows.

Said weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) are calculated | required by a gel permeation chromatography (GPC) measurement. The weight average molecular weight is a polystyrene equivalent weight average molecular weight measured with the following apparatus and conditions, and the molecular weight distribution is a value calculated from the number average molecular weight (Mn) measured in the same manner and the above weight average molecular weight.
<GPC measurement device>
Column: “TOSO GMHHR-H (S) HT” manufactured by Tosoh Corporation
Detector: RI detection for liquid chromatogram "WATERS 150C" manufactured by Waters Corporation
<Measurement conditions>
Solvent: 1,2,4-trichlorobenzene Measurement temperature: 145 ° C
Flow rate: 1.0 mL / min Sample concentration: 2.2 mg / mL
Injection volume: 160 μL
Calibration curve: Universal Calibration
Analysis program: HT-GPC (Ver.1.0)

The propylene-based resin (B) is not particularly limited as long as the above requirements are satisfied, and may be a propylene homopolymer or a copolymer. In the case of a copolymer, the copolymerization ratio of propylene units exceeds 50 mol%, preferably 60 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, still more preferably 95 mol%. That's it. The copolymerizable monomer is at least one selected from the group consisting of ethylene and an α-olefin having 4 to 30 carbon atoms. Specific examples include ethylene, 1-butene, 1-pentene, 1-hexene, Examples include 1-octene and 1-decene.
When the polypropylene resin is a copolymer, the polypropylene resin contains at least one constituent unit selected from the group consisting of ethylene and an α-olefin having 4 to 30 carbon atoms, exceeding 0 mol% and not more than 20 mol%. It is preferable.

(Producing method of propylene resin (B))
The propylene-based resin (B) can be produced using, for example, a metallocene-based catalyst as described in International Publication No. 2003/087172. In particular, those using a transition metal compound in which a ligand forms a cross-linked structure via a cross-linking group are preferred, and in particular, a transition metal compound that forms a cross-linked structure via two cross-linking groups and Metallocene catalysts obtained by combining promoters are preferred.

For example,
(I) General formula (I)

[In the formula, M represents a group 3-10 of the periodic table or a lanthanoid series metal element, and E ¹ and E ² represent a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, a heterocyclopentadienyl group, respectively. A ligand selected from a substituted heterocyclopentadienyl group, an amide group, a phosphide group, a hydrocarbon group, and a silicon-containing group, which forms a cross-linked structure via A ¹ and A ² In addition, they may be the same or different from each other, X represents a σ-bonded ligand, and when there are a plurality of X, the plurality of X may be the same or different, and other X, E ¹ , E ² or Y may be cross-linked. Y represents a Lewis base, and when there are a plurality of Y, the plurality of Y may be the same or different, and may be cross-linked with other Y, E ¹ , E ² or X, and A ¹ and A ² are A divalent bridging group that binds two ligands, a hydrocarbon group having 1 to 20 carbon atoms, a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, a germanium-containing group, a tin-containing group _{, -O -, - CO -,} - S -, - SO 2 -, - Se -, - NR 1 -, - PR 1 -, - P (O) R 1 -, - BR 1 - or -AlR ¹ - R ¹ represents a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, which may be the same as or different from each other. q represents an integer of 1 to 5 and represents [(M valence) -2], and r represents an integer of 0 to 3. ]
And (ii) (ii-1) a compound capable of reacting with the transition metal compound of component (i) or a derivative thereof to form an ionic complex, and (ii-2) an aluminoxane And a polymerization catalyst containing at least one component selected from the group consisting of:

  As the transition metal compound (i), a ligand is preferably a (1,2 ′) (2,1 ′) double-bridged transition metal compound, such as (1,2′-dimethylsilylene) ( 2,1'-dimethylsilylene) -bis (3-trimethylsilylmethylindenyl) zirconium dichloride.

  Specific examples of the compound of component (ii-1) include triethylammonium tetraphenylborate, tri-n-butylammonium tetraphenylborate, trimethylammonium tetraphenylborate, tetraethylammonium tetraphenylborate, methyl tetraphenylborate (tri- n-butyl) ammonium, benzyl tetraphenylborate (tri-n-butyl) ammonium, dimethyldiphenylammonium tetraphenylborate, triphenyl (methyl) ammonium tetraphenylborate, trimethylanilinium tetraphenylborate, methylpyridinium tetraphenylborate, tetra Benzylpyridinium phenylborate, methyl tetraphenylborate (2-cyanopyridinium), triethyl tetrakis (pentafluorophenyl) borate Ammonium, tetrakis (pentafluorophenyl) tri-n-butylammonium borate, tetrakis (pentafluorophenyl) triphenylammonium borate, tetrakis (pentafluorophenyl) tetra-n-butylammonium borate, tetraethylammonium tetrakis (pentafluorophenyl) borate Benzyl tetrakis (pentafluorophenyl) ammonium borate (tri-n-butyl), methyldiphenylammonium tetrakis (pentafluorophenyl) borate, triphenyl (methyl) ammonium tetrakis (pentafluorophenyl) borate, tetrakis (pentafluorophenyl) boric acid Methylanilinium, tetrakis (pentafluorophenyl) dimethylanilinium borate, tetrakis (pentafluorophenyl) Nyl) trimethylanilinium borate, methylpyridinium tetrakis (pentafluorophenyl) borate, benzylpyridinium tetrakis (pentafluorophenyl) borate, methyl tetrakis (pentafluorophenyl) borate (2-cyanopyridinium), benzyl tetrakis (pentafluorophenyl) borate (2-cyanopyridinium), methyl tetrakis (pentafluorophenyl) borate (4-cyanopyridinium), triphenylphosphonium tetrakis (pentafluorophenyl) borate, tetrakis [bis (3,5-ditrifluoromethyl) phenyl] dimethylaniline borate Nitrogen, ferrocenium tetraphenylborate, silver tetraphenylborate, trityl tetraphenylborate, tetraphenylporphyrin manganese tetraphenylborate , Ferrocenium tetrakis (pentafluorophenyl) borate, tetrakis (pentafluorophenyl) borate (1,1′-dimethylferrocenium), tetrakis (pentafluorophenyl) decamethylferrocenium borate, silver tetrakis (pentafluorophenyl) borate , Tetrakis (pentafluorophenyl) trityl borate, tetrakis (pentafluorophenyl) lithium borate, tetrakis (pentafluorophenyl) sodium borate, tetrakis (pentafluorophenyl) borate tetraphenylporphyrin manganese, silver tetrafluoroborate, silver hexafluorophosphate, Examples include silver hexafluoroarsenate, silver perchlorate, silver trifluoroacetate, and silver trifluoromethanesulfonate.

  Examples of the aluminoxane as the component (ii-2) include known chain aluminoxanes and cyclic aluminoxanes.

  Trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, dimethylaluminum chloride, diethylaluminum chloride, methylaluminum dichloride, ethylaluminum dichloride, dimethylaluminum fluoride, diisobutylaluminum hydride, diethylaluminum hydride, ethylaluminum sesquichloride, etc. A polypropylene resin may be produced by using together the organoaluminum compound.

  Content of the propylene-type resin (B) contained in the said polypropylene-type resin composition is 1 mass% or more and 70 mass% or less. If it is less than 1% by mass, sufficient crimpability cannot be obtained, and if it exceeds 70% by mass, the fiber properties are inferior. From such a viewpoint, the content of the propylene-based resin (B) is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 30% by mass or less. It is.

  A commercial item can be used as a propylene-type resin (B). Specific examples include “S-400”, “S600”, and “S901” of “L-MODU” (registered trademark) (manufactured by Idemitsu Kosan Co., Ltd.).

  The said polypropylene resin composition can mix | blend arbitrary additives in the range which does not inhibit the effect of this embodiment. Specific examples of additives include foaming agents, crystal nucleating agents, anti-glare stabilizers, UV absorbers, light stabilizers, heat stabilizers, antistatic agents, mold release agents, flame retardants, synthetic oils, waxes, electrical properties Improver, anti-slip agent, anti-blocking agent, viscosity modifier, anti-coloring agent, anti-fogging agent, lubricant, pigment, dye, plasticizer, softener, anti-aging agent, hydrochloric acid absorbent, chlorine scavenger, antioxidant And anti-adhesive agents.

If the above-mentioned propylene-based resin (B) is used for the first component (also referred to as a low crystal component) constituting the crimp fiber, the second component (also referred to as a high crystal component) Although not particularly limited, from the viewpoint of exhibiting the effects of the present embodiment, the high crystal component preferably includes a propylene-based resin, and more preferably includes a propylene homopolymer.
The content of the propylene-based resin contained in the high crystal component is preferably 80% by mass or more, more preferably 85% by mass or more, and still more preferably 90% by mass or more, when the high crystal component is 100% by mass. And the upper limit is 100% by mass.
In addition, the high crystal component can be blended with any additive within a range that does not impair the effects of the present embodiment. Specific examples of the additive include those exemplified in the section of the polypropylene resin composition.

Further, the crimped fiber of the present embodiment is preferably a side-by-side type fiber or an eccentric core-sheath type fiber, and more preferably an eccentric core-sheath type fiber.
When the crimped fiber of the present embodiment is an eccentric core-sheath fiber, the mass ratio of the core component to the sheath component is preferably 10/90 to 90/10, more preferably 30/70 to 70/30, and further Preferably it is 40 / 60-60 / 40. When the mass ratio of the core component and the sheath component is within the above range, crimpability is further improved.

<Method for producing crimped fiber>
The method for producing the crimped fiber of the present embodiment is not particularly limited, but preferably includes a step of melt spinning the raw material containing the above-described polypropylene resin composition and drawing the obtained fiber.

In this step, first, a raw material containing the above-described polypropylene resin composition is melt-spun. This melt spinning can be performed by a known method. For example, a method of manufacturing using a monofilament manufacturing facility that is extruded from a single hole (hereinafter simply referred to as monofilament), and a method of manufacturing using a multifilament manufacturing facility that includes a nozzle having a plurality of holes and a winder (Hereinafter simply referred to as “multifilament”), a composite spinning method by melt spinning represented by a spunbond method, a melt blow method, an electrospinning method, and the like. Among these, monofilament or multifilament is preferable, and multifilament is more preferable.
In this embodiment, the above-mentioned propylene-based resin (B) is used as one component constituting the fiber. Then, by adjusting the resin discharge amount of each resin component as appropriate and discharging from a spinneret (for example, an eccentric core-sheath type, a side-by-side type, a modified cross-section type, etc.) having a composite spinning nozzle, the undrawn fiber is formed by spinning. can get.

Next, the obtained fiber (undrawn fiber) is drawn. Although the process of extending | stretching is not specifically limited, Preferably, it has the process (1) of winding up the obtained fiber once, and the process (2) of extending the fiber wound up by this process (1).
Before winding up the fiber obtained in the step (1), the fiber may be stretched in-line so as not to deteriorate the stretchability in the step (2) (in-line stretching).

In the step (2), the fiber wound in the step (1) is stretched as a separate step from the viewpoint of further improving the crimpability (offline stretching).
There is no restriction | limiting in particular in the extending | stretching method, A well-known method is employable. For example, roll stretching that stretches by adjusting the rotational speed ratio of two or more rolls and applying tensile stress to the fibers can be mentioned. Stretching may be performed in one stage, or may be performed in two or more stages.
Stretching can be performed without heating (for example, 25 ° C.) or under heating. In the case of heating, it is preferably performed at 80 ° C. or less, more preferably 60 ° C. or less, and further preferably 40 ° C. or less, from the viewpoint of further suppressing winding around the roll and enhancing the crimpability.
The final draw ratio obtained from the product of the inline draw ratio and the off-line draw ratio may be appropriately adjusted according to the use of the fiber, but from the viewpoint of more strongly expressing the fiber strength and crimpability, it is preferably 2 times or more, More preferably 3 times or more, still more preferably 4 times or more, and preferably 8 times or less, more preferably 7 times or less from the viewpoint of further suppressing yarn breakage or whitening. Here, the draw ratio means a ratio of fiber lengths before and after drawing. By using the above-mentioned propylene-based resin (B) as one component constituting the fiber, whitening of the obtained crimped fiber can be further suppressed.

In this embodiment, the above-mentioned propylene-based resin (B) is used as one component constituting the fiber, and the crimped fiber obtained by stretching the fiber as described above is heat-treated at a temperature of 120 ° C. for 15 minutes. The subsequent crimp rate can be 30% or more, preferably 40% or more, more preferably 50% or more.
In addition, the crimp rate after heat-processing can be specifically measured by the method as described in an Example.

Further, the crimped fiber of the present embodiment has a tensile strength according to JIS L1013 (2010) of 1.5 cN / Dtex or more, preferably 2.0 cN / Dtex or more, more preferably 2.5 cN / Dtex or more. Can do.
Specifically, the tensile strength can be measured by the method described in Examples.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited at all by these examples.

[DSC measurement]
Using a differential scanning calorimeter (Perkin Elmer, “DSC-7”), 10 mg of the sample was held at −10 ° C. for 5 minutes in a nitrogen atmosphere, and then heated at 10 ° C./min. It calculated | required as a melting endotherm ((DELTA) HD) from a melting endothermic curve. Moreover, melting | fusing point (Tm-D) was calculated | required from the peak top of the peak observed on the highest temperature side of the obtained melting endothermic curve.
The melting endotherm (ΔH-D) is a differential scanning calorimeter (manufactured by Perkin Elmer Co., Ltd.) with a line connecting a point on the low temperature side where there is no change in heat quantity and a point on the high temperature side where there is no change in heat quantity as the baseline. , “DSC-7”), and calculating the area surrounded by the line portion including the peak of the melting endothermic curve obtained by DSC measurement and the base line.

[Semi-crystallization time]
Using a differential scanning calorimeter (DSC) (manufactured by Perkin Elmer, trade name: “DSC-7”), the measurement was performed by the following method.
(1) Hold 10 mg of sample at 25 ° C. for 5 minutes, raise the temperature to 320 ° C. at 320 ° C./second and hold for 5 minutes. By cooling to 25 ° C. at 320 ° C./second and holding for 300 minutes, the time change of the calorific value in the isothermal crystallization process is measured.
(2) When the integrated value of the calorific value from the start of isothermal crystallization to the completion of crystallization is 100%, the time from the start of isothermal crystallization until the integrated value of the calorific value becomes 50% is semi-crystallized. Sought as time.

[Melt flow rate (MFR)]
The propylene homopolymer (A) was measured under the conditions of a temperature of 230 ° C. and a load of 2.16 kg according to JIS K7210.

[Weight average molecular weight (Mw), molecular weight distribution (Mw / Mn) measurement]
The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by gel permeation chromatography (GPC) method to determine the molecular weight distribution (Mw / Mn). For the measurement, the following apparatus and conditions were used, and polystyrene-reduced weight average molecular weight and number average molecular weight were obtained. The molecular weight distribution (Mw / Mn) is a value calculated from these weight average molecular weight (Mw) and number average molecular weight (Mn).
<GPC measurement device>
Column: “TOSO GMHHR-H (S) HT” manufactured by Tosoh Corporation
Detector: RI detection for liquid chromatogram "WATERS 150C" manufactured by Waters Corporation
<Measurement conditions>
Solvent: 1,2,4-trichlorobenzene Measurement temperature: 145 ° C
Flow rate: 1.0 mL / min Sample concentration: 2.2 mg / mL
Injection volume: 160 μL
Calibration curve: Universal Calibration
Analysis program: HT-GPC (Ver.1.0)

In the following examples, the following raw materials were used.
<Propylene homopolymer (A)>
Propylene homopolymer (A-1):
・ "Prime Polypro S137L" (manufactured by Prime Polymer Co., Ltd.)
In addition, Table 1 shows the melting point (Tm-D) and MFR of the propylene homopolymer (A-1) measured by the above method.
Propylene homopolymer (A-2):
・ "Prime Polypro S119" (manufactured by Prime Polymer Co., Ltd.)
In addition, Table 1 shows the melting point (Tm-D) and MFR of the propylene homopolymer (A-2) measured by the above method.

<Propylene resin (B)>
Propylene resin (B-1):
・ "L-MODU (registered trademark) S400" (made by Idemitsu Kosan Co., Ltd., homopolypropylene)
Propylene resin (B-2):
・ "L-MODU (registered trademark) S901" (made by Idemitsu Kosan Co., Ltd., homopolypropylene)
The physical properties of the propylene resins (B-1) and (B-2) measured by the above method are shown in Table 2.

  The following measurements and evaluations were performed on the fibers obtained in each example.

[Fineness]
It measured based on JIS L1013 (2010).

[Tensile strength]
It measured based on JIS L1013 (2010).

[Elastic modulus]
It measured based on JIS L1013 (2010).

[Elongation]
It measured based on JIS L1013 (2010).

[Crimp ratio after stretching]
About the obtained fiber, sample length was measured as follows and it computed from following formula (1). The number of measurement samples was three, and the average value was the crimp rate after stretching.
Crimp rate after stretching (%) = [(L0−L1) / L0] × 100 (1)
In the formula (1), L1 is a sample length (mm) with a load of 0.177 mN × fineness (tex), and L0 is a sample length (mm with a load of 8.82 mN × fineness (tex). ).

[Crimping rate after heat treatment]
The obtained fiber was heat-treated at a temperature of 120 ° C. for 15 minutes. The sample length was measured as follows and calculated from the following formula (2). The number of measurement samples was three, and the average value was the crimp rate after the heat treatment.
Crimp rate after heat treatment (%) = [(L0−L2) / L0] × 100 (2)
In Formula (2), L0 is a sample length (mm) in a state where a load of 8.82 mN × fineness (tex) is applied, and L2 is a fiber after heat treatment, and a load of 0.177 mN × fineness (tex) is applied. It is the sample length (mm) of the state.
An electron micrograph (magnification: 200 times) taken after heat treatment of the eccentric core-sheathed crimped fiber obtained in Example 10 is shown in FIG. 1, and an optical micrograph (magnification: 50 times) is shown in FIG. .

[Whitening]
The obtained fiber was visually observed and evaluated according to the following criteria.
[Evaluation criteria]
A: No whitening was observed B: Some whitening was observed C: Whitening was observed

Reference example 1
A core component and a sheath component were respectively prepared with the types and blending amounts described in Table 3-1.
The core component resin and the sheath component resin are melt-extruded at a spinning temperature of 230 ° C. using separate single-screw extruders, and a single-hole discharge amount of 0. The molten resin was discharged at 45 g / min so that the mass ratio of the core component: sheath component was 50:50.
The discharged fiber was drawn by a drawing machine using a heated godet roller under the conditions of an inline drawing temperature of 95 ° C. and an inline drawing ratio of 2.7 times, and then wound up on a winding roll. About the obtained eccentric core-sheath fiber, it evaluated using the above-mentioned measuring method. The results are shown in Table 3-1.
In Tables 3-1 to 3-4, the degree of eccentricity “maximum” represents the arrangement (maximum eccentricity) of the nozzles arranged at positions where the circumference on the core side and the circumference on the sheath side substantially contact each other. , “Medium” represents a nozzle arrangement (medium eccentricity) at an intermediate position between the maximum eccentricity and the concentricity.

Reference Examples 2-12
A core component and a sheath component were prepared with the types and blending amounts described in Table 3-1 and Table 3-3, respectively, and the eccentricity, stretching temperature, and stretching ratio described in Table 3-1 and Table 3-3 were changed. Except that, the eccentric core-sheath fiber of Reference Examples 2 to 12 was obtained in the same manner as Reference Example 1. About the obtained eccentric core-sheath fiber, it evaluated using the above-mentioned measuring method. The results are shown in Table 3-1 and Table 3-3.

Example 1
The core component and the sheath component were respectively prepared with the types and blending amounts described in Table 3-2.
The core component resin and the sheath component resin are melt-extruded at a spinning temperature of 230 ° C. using a composite spinning apparatus, and a single-hole discharge amount of 0.45 g / from a core-sheath eccentric composite nozzle (72 holes) having a nozzle diameter of 0.7. Minutes, the molten resin was discharged such that the mass ratio of the core component: sheath component was 50:50.
The discharged fiber was drawn by a drawing machine using a heated godet roller under the conditions of an inline drawing temperature of 95 ° C. and an inline drawing ratio of 2.7 times, and then wound up on a winding roll.

  Next, the fiber was fed out from the take-up roll, and stretched again by a stretching machine using a heated godet roller under the conditions of an offline stretching temperature of 25 ° C. and an offline stretching ratio of 1.9 times. The obtained eccentric core-sheathed crimped fiber was evaluated using the measurement method described above. The results are shown in Table 3-2.

Examples 2-10
A core component and a sheath component are respectively prepared in the types and blending amounts described in Table 3-2 and Table 3-3, and the eccentricity, inline stretching temperature and inline stretching ratio described in Table 3-2 and Table 3-3, And the eccentric core-sheath type | mold crimp fiber of Examples 2-10 was obtained like Example 1 except having changed into the off-line extending | stretching temperature and off-line extending | stretching magnification. The obtained eccentric core-sheathed crimped fiber was evaluated using the measurement method described above. The results are shown in Table 3-2 and Table 3-3.

Comparative Example 1
The core component and the sheath component were respectively prepared with the types and blending amounts described in Table 3-4.
The core component resin and the sheath component resin are melt-extruded at a spinning temperature of 230 ° C. using a composite spinning apparatus, and a single-hole discharge amount of 0.45 g / from a core-sheath eccentric composite nozzle (72 holes) having a nozzle diameter of 0.7. Minutes, the molten resin was discharged such that the mass ratio of the core component: sheath component was 50:50.
The discharged fiber was stretched by a stretching machine using a heated godet roller under the conditions of an inline stretching temperature of 110 ° C. and an inline stretching ratio of 2.0 times, and then wound on a winding roll.

  Next, the fiber was pulled out from the take-up roll and stretched under the conditions of an offline stretching temperature of 25 ° C. and an offline stretching ratio of 2.2 times by a stretching machine using a heated godet roller. The obtained eccentric core-sheathed crimped fiber was evaluated using the measurement method described above. The results are shown in Table 3-4.

Comparative Examples 2-4
The core component and the sheath component were respectively prepared with the types and blending amounts described in Table 3-4, except that the inline stretching temperature and inline stretching ratio described in Table 3-4 were changed to the offline stretching temperature and offline stretching ratio. In the same manner as in Comparative Example 1, eccentric core-sheath type crimped fibers of Comparative Examples 2 to 4 were obtained. The obtained eccentric core-sheathed crimped fiber was evaluated using the measurement method described above. The results are shown in Table 3-4.

From the results of Tables 3-1 to 3-4, it can be seen that the tensile strength is improved by off-line drawing of the fiber obtained by spinning. In Reference Examples 1 to 12 with only in-line stretching, the crimp rate after the heat treatment was as low as 26% or less. Moreover, in Comparative Examples 1-4 which does not use propylene-type resin (B) in any of a core component and a sheath component, it was a result with the crimping rate after heat processing all being as low as 16% or less. On the other hand, in Examples 1-10, the result with a high crimp rate of 34% or more after heat treatment was obtained. Here, FIG. 1 shows an electron micrograph (magnification: 200 times) taken after heat treatment of the eccentric core-sheath crimped fiber of Example 10, and FIG. 2 shows an optical micrograph (magnification 50 times). The crimp ratio after heat-treating the eccentric core-sheath-type crimped fiber of Example 10 is as high as 69%, which indicates that the crimpability is excellent as shown in FIGS. Moreover, in Examples 1 and 6 to 8 in which the amount of the propylene-based resin (B) used for the core component or the sheath component is small, the crimp rate after offline stretching is low, but the crimp rate after heat treatment is any Is also 50% or more.
Further, the higher the final draw ratio obtained from the product of the inline draw ratio and the off-line draw ratio, the higher the tensile strength of the resulting fiber, but there is a tendency to whiten. On the other hand, it has confirmed that whitening can be suppressed by using propylene-type resin (B) for either a core component or a sheath component (refer Example 1 and Comparative Example 2).

[Crimp retention rate and crimp restoration rate]
About the eccentric core-sheath-type crimped fibers obtained in Examples 8 and 10 (hereinafter also simply referred to as crimped fibers), after holding for 4 days under a load of 8.82 cN × fineness (tex), From the crimp ratio after stretching calculated from the formula (1), the crimp retention was calculated from the following formula (3). The results are shown in Table 4.
Crimp retention ratio (%) = [crimp ratio after stretching (%) / crimp ratio of crimped fiber (%)] × 100 (3)

After heating this fiber at 60 ° C. for 15 minutes, the crimp restoration rate was calculated from the following formula (4) from the crimp rate after the heat treatment calculated from the above formula (2). The results are shown in Table 4.
Crimp restoration rate (%) = [crimp rate after heat treatment (%) / crimp rate of crimped fiber (%)] × 100 (4)
Furthermore, the same operation was repeated 3 times every 7 days of load retention time, and the crimp retention rate and the crimp restoration rate were calculated from the above formulas (3) and (4). The results are shown in Table 4.

As shown in Table 4, Example 10 using only the propylene-based resin (B) as the core component has a crimp recovery rate of 70% or more by performing a heat treatment operation, and has low repulsion. It turns out that it is a crimped fiber excellent in stress followability.
Further, in Example 8 using the core component obtained by adding the propylene-based resin (B) to the propylene homopolymer (A), the crimp recovery rate is 95% or higher, which is higher than Example 10 and after holding the load. It can be seen that this is a crimped fiber that maintains a crimp retention of 50% or more, is difficult to loosen, and has a high crimp recovery rate by heat treatment.

Claims (13)

  A propylene homopolymer (A) having a melting point (Tm-D) measured by a differential scanning calorimeter (DSC) of more than 120 ° C. is 30% by mass to 99% by mass, and a differential scanning calorimeter (DSC) is used. The melting endotherm (ΔH-D) obtained from a melting endotherm curve obtained by holding the sample at −10 ° C. for 5 minutes in a nitrogen atmosphere and raising the temperature at 10 ° C./min is 0 J / g or more and 80 J / g. a polypropylene resin composition containing 1% by mass or more and 70% by mass or less of a propylene resin (B) that is g or less, the tensile strength according to JIS L1013 (2010) is 1.5 cN / Dtex or more, and the temperature A crimped fiber having a crimp rate of 30% or more by heat treatment at 120 ° C. for 15 minutes.   The crimped fiber according to claim 1, wherein a semi-crystallization time of the propylene-based resin (B) exceeds 15 seconds.   According to JIS K7210 of the propylene homopolymer (A), the melt flow rate (MFR) measured under the conditions of a temperature of 230 ° C. and a load of 2.16 kg is 0.1 g / 10 min to 1,000 g / 10 min. The crimped fiber according to claim 1 or 2.   The crimped fiber according to any one of claims 1 to 3, wherein the propylene-based resin (B) has a weight average molecular weight (Mw) of 10,000 or more and 300,000 or less.   The melting | fusing point (Tm-D) measured by the differential scanning calorimeter (DSC) of the said propylene-type resin (B) is 40 to 120 degreeC, The soot as described in any one of Claims 1-4 Crimped fiber.   The crimped fiber according to any one of claims 1 to 5, wherein the crimped fiber is a side-by-side type fiber or an eccentric core-sheath type fiber.   The crimped fiber according to claim 6, wherein the crimped fiber is an eccentric core-sheath fiber.   The crimped fiber according to claim 7, wherein in the eccentric core-sheath fiber, a mass ratio of the core component to the sheath component is 10/90 to 90/10. A method for producing a crimped fiber according to any one of claims 1 to 8,
A method for producing crimped fibers, comprising melt-spinning a raw material containing the polypropylene resin composition and drawing the obtained fibers.   The manufacturing method of the crimp fiber of Claim 9 whose final draw ratio is 2 times or more and 8 times or less. The step of stretching the step (1) of winding up the obtained fiber once;
The manufacturing method of the crimped fiber of Claim 9 or 10 which has the process (2) of extending | stretching the fiber wound by the said process (1).   The method for producing a crimped fiber according to claim 11, wherein the stretching in the step (2) is performed without heating.   The method for producing a crimped fiber according to any one of claims 9 to 12, wherein the melt spinning is a method for producing using a multifilament production facility having a nozzle having a plurality of holes and a winder. .