JP2023102662A - Sheet-like cotton and fiber product including the same and sheet-like cotton manufacturing method - Google Patents

Abstract

To provide a sheet-like cotton having excellent heat-retaining property and feeling and a manufacturing method thereof.SOLUTION: A sheet-like cotton including 40 mass% or more and less than 95 mass% of a fiber (X), which has a cross section having at least two of (a) region and (b) region and a fiber length of 40 mm or less, and more than 5 mass% and 60 mass% or less of a fiber (Y) made of one or more types of resin selected from a group consisting of polyester, polyamide, thermoplastic polyacrylonitrile, thermoplastic polyurethane, polypropylene, polyethylene, and cellulose derivative, a manufacturing method of the sheet-like cotton, and a fiber product including the sheet-like cotton are provided, where (a) region is formed of 4-methyl-1-pentene polymer (A) in which MFR (A) (260°C, 5.0 kg load) is 30 to 180 g/10 min, and (b) region is formed of 4-methyl-1-pentene polymer (B) in which MFR (B) (260°C, 5.0 kg load) is more than 180 g/10 min and 400 g/10 min or less.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to sheet-like cotton, textile products containing the same, and a method for producing sheet-like cotton.

BACKGROUND ART There has been a demand for woven and knitted fabrics that are lightweight and excellent in bulkiness, and various fibers have been proposed so far.
Polymethylpentene has a smaller specific gravity than polyester, polyethylene, and polypropylene conventionally used for fibers, and is extremely lightweight. In addition, since it has a higher melting point and softening point than other polyolefins, excellent heat resistance, and high resistance to heat and light, it can be applied to clothing applications.

As a fiber using polymethylpentene, Patent Document 1 discloses a side-by-side composite fiber made of polymethylpentene-based resin (A) and polymethylpentene-based resin (B), where MFR (A) < MFR (B), where MFR (measurement temperature 260 ° C., load 5 kg) is MFR (A) and MFR (B). Further, in Examples of Patent Document 1, it is described that a side-by-side type composite fiber having a crimp number of 1.1 to 3.0 crimps/cm was obtained by using a polymethylpentene-based resin (A) having an MFR of 100 g/10 minutes and a polymethylpentene-based resin (B) having an MFR of 180 g/10 minutes.

JP 2015-121007 A

Polymethylpentene has high crystallinity and is resistant to shrinkage. Therefore, when polymethylpentene alone is fiberized, it is difficult to impart crimpability. In addition to the crimpability described above, Patent Document 1 does not discuss a method for forming sheet cotton from the conventional polymethylpentene-based fibers described in the same document, and there is a demand for the development of sheet-like cotton that is superior in heat retention and texture to sheet-like cotton formed from conventional polymethylpentene-based fibers.
An object to be solved by an embodiment of the present invention is to provide sheet-like cotton excellent in heat retention and texture, and a method for producing the same. Another problem to be solved by one embodiment of the present invention is to provide a textile product containing sheet-like cotton excellent in heat retention and texture.

Means for solving the above problems include the following aspects.
<1> A fiber (X) whose cross section has at least two of the following regions (a) and (b) and has a fiber length of 40 mm or less;
Fibers (Y) made of one or more resins selected from the group consisting of polyester, polyamide, thermoplastic polyacrylonitrile, thermoplastic polyurethane, polypropylene, polyethylene and cellulose derivatives;
including
Sheet cotton, wherein the content of the fiber (X) is 40% by mass or more and less than 95% by mass with respect to the total mass of the sheet cotton, and the content of the fiber (Y) is more than 5% by mass and 60% by mass or less with respect to the total mass of the sheet cotton;
(a) region: MFR (A) (260° C., 5.0 kg load) consisting of a 4-methyl-1-pentene polymer (A) in the range of 30 to 180 g/10 min;
(b) Region: MFR (B) (260° C., 5.0 kg load) consists of a 4-methyl-1-pentene polymer (B) in the range of over 180 g/10 min and 400 g/10 min or less.
<2> The cotton sheet according to <1>, wherein the ratio of MFR(A) to MFR(B) (MFR(A)/MFR(B)) is 0.10 to 0.65.
<3> The cotton sheet according to <1> or <2>, wherein the fibers are conjugate fibers having a crimped structure of at least one of side-by-side type and eccentric sheath-core type.
<4> The 4-methyl-1-pentene polymer (A) satisfies the following requirements (AI) to (A-III),
The cotton sheet according to any one of <1> to <3>, wherein the 4-methyl-1-pentene polymer (B) satisfies the following requirements (BI) to (B-III);
(AI) The content (U1) of structural units derived from 4-methyl-1-pentene is 100 to 90.0 mol%, and the content (U2) of structural units derived from olefins selected from the group consisting of ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) is 0 to 10.0 mol%;
(A-II) Density measured according to JIS K7112 (density gradient tube method) is in the range of 820 to 850 kg/m ³ ;
(A-III) a melting point (Tm) of 200° C. to 260° C. as measured by a differential scanning calorimeter (DSC);
(BI) the content (U3) of structural units derived from 4-methyl-1-pentene is 100 to 90.0 mol%, and the content (U4) of structural units derived from ethylene and an α-olefin having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) is 0 to 10.0 mol%;
(B-II) Density measured according to JIS K7112 (density gradient tube method) is in the range of 820 to 850 kg/m ³ ;
(B-III) It has a melting point (Tm) of 200° C. to 260° C. as measured by a differential scanning calorimeter (DSC).
<5> The method for producing a cotton sheet according to any one of <1> to <4>, comprising: a 4-methyl-1-pentene polymer (A) having an MFR (A) measured at 260°C and 5.0 kgf in the range of 30 to 180 g/10 min; A method for producing sheet-like cotton, comprising a step of compounding and melt-spinning a 4-methyl-1-pentene-based polymer (B) within the range, and a step of forming the fiber into a sheet.
<6> A textile product containing the sheet-like cotton according to any one of <1> to <4>.
<7> The textile product according to <6>, which is a blanket, rug, bedding, cushion, mat, or clothing.
<8> The textile product according to <6>, which is a cushioning material, a sound absorbing material, a sound insulating material, a vibration insulating material, a heat insulating material, or a heat insulating material.

According to one embodiment of the present invention, sheet-like cotton excellent in heat retention and texture and a method for producing the same are provided. According to one embodiment of the present invention, there is provided a textile product containing sheet-like cotton excellent in heat retention and texture.

The contents of the present invention will be described in detail below. The description of the contents of the constituent elements described below may be made based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.
As used herein, the term "polymer" is a concept including homopolymers and copolymers.
In the present specification, the term "to" indicating a numerical range is used to include the numerical values before and after it as lower and upper limits.
In the present specification, "-" indicating a numerical range means that the unit described either before or after it indicates the same unit unless otherwise specified.
In the present specification, a combination of two or more preferred aspects is a more preferred aspect.
The present invention will be described in detail below.

(sheet cotton)
The sheet-shaped cotton according to the present invention includes fibers (X) having a fiber cross section having at least two regions (a) and (b) below and having a fiber length of 40 mm or less, and fibers (Y) made of one or more resins selected from the group consisting of polyester, polyamide, thermoplastic polyacrylonitrile, thermoplastic polyurethane, polypropylene, polyethylene, and cellulose derivatives, and the content of the fibers (X) is 40% by mass or more and less than 95% by mass with respect to the total mass of the sheet-shaped cotton. and the content of the fiber (Y) is more than 5% by mass and not more than 60% by mass with respect to the total mass of the cotton sheet;
(a) region: MFR (A) (260° C., 5.0 kg load) consisting of a 4-methyl-1-pentene polymer (A) in the range of 30 to 180 g/10 min;
(b) Region: MFR (B) (260° C., 5.0 kg load) consists of a 4-methyl-1-pentene polymer (B) in the range of over 180 g/10 min and 400 g/10 min or less.
The sheet-like cotton according to the present invention is excellent in heat retention and texture by having the above structure. The reason for this is not clear or is presumed as follows.
The sheet-like cotton according to the present invention contains the specific contents of the fibers (X) and (Y) made of the specific components, and the fibers (X) have a specific fiber length. Therefore, for example, the sheet-like cotton can be easily formed compared to the sheet-like cotton containing 95% by mass or more of the fiber (X) with respect to the total mass of the sheet-like cotton. In addition, since the main component is a fiber made of 4-methyl-1-pentene polymer, which has a low thermal conductivity and relatively low rigidity compared to other resins, it has excellent heat retention and texture. Details of each configuration of the sheet cotton will be described below.

<Fiber (X)>
The sheet-shaped cotton according to the present invention includes fibers (X) having a fiber cross section having at least two regions (a) and (b) below and having a fiber length of 40 mm or less, and the content of the fibers (X) is 40% by mass or more and less than 95% by mass with respect to the total mass of the sheet-shaped cotton.
The fiber (X) is not particularly limited as long as the cross section of the fiber has at least two regions (a) and (b), and the fiber (X) may further have other regions other than the (a) region and the (b) region.
As a method for confirming whether or not the cross section of the fiber (X) has at least two regions, the (a) region and the (b) region, the fiber is extracted from the sheet-like cotton, the extracted fiber is cut in the minor axis direction, and the cross section is observed with a laser microscope (SEM) (magnification × 100).

<<(a) region>>
Region (a) consists of a 4-methyl-1-pentene polymer (A) having an MFR (melt flow rate) (A) (260° C., 5.0 kg load) in the range of 30 to 180 g/10 min.

[4-methyl-1-pentene polymer (A)]
The MFR (A) of the 4-methyl-1-pentene polymer (A) measured at 260° C. under a load of 5.0 kg (hereinafter also simply referred to as “MFR (A)”) is 30 to 180 g/10 min, preferably 30 to 150 g/10 min, more preferably 50 to 145 g/10 min.
When the MFR (A) is 30 g/10 min or more, the polymer (A) has a melt viscosity suitable for spinnability and tends to be more excellent in spinnability. In addition, when the MFR (A) does not exceed 180 g/10 min, the MFR (A) can increase the difference in melt viscosity from the MFR (B) of the 4-methyl-1-pentene polymer (B) described later, and the crimpability of the resulting fiber is excellent, and a sheet-like cotton excellent in heat retention and texture can be obtained.

In addition, since the MFR (A) of the 4-methyl-1-pentene polymer (A) is within the above range, it becomes easy to set the ratio (MFR (A)/MFR (B)) to the MFR (B) of the 4-methyl-1-pentene polymer (B) constituting the fiber contained in the sheet-like cotton within the range of 0.10 to 0.65.

The 4-methyl-1-pentene-based polymer (A) preferably satisfies the following requirements (AI) to (A-III) from the viewpoint that the resulting cotton sheet has excellent heat retention and texture.

<Requirements (AI)>
The 4-methyl-1-pentene polymer (A) preferably has a content (U1) of structural units derived from 4-methyl-1-pentene of 100 to 90.0 mol%, more preferably 100 to 93.0 mol%, still more preferably 99.5 to 95.0 mol%, and is derived from an olefin selected from the group consisting of ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene). The content (U2) of the structural unit is preferably 0 to 10.0 mol%, more preferably 0 to 7.0 mol%, still more preferably 0.5 to 5.0 mol%. However, the total amount of (U1) and (U2) is 100 mol%.

When the 4-methyl-1-pentene polymer (A) is a copolymer, ethylene, propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4,4-dimethyl-1-pentene, 4-methyl-1-hexene, 4 , 4-dimethyl-1-hexene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene. Among these, preferred are ethylene, propylene, 1-butene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene and 1-octadecene. More preferred are 1-hexene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-hexadecene and 1-octadecene. These α-olefins may be used singly or in combination of two or more.

Structural units derived from 4-methyl-1-pentene in the 4-methyl-1-pentene-based polymer (A) and ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) The amount of structural units derived from ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) can be adjusted by adjusting the amount of 4-methyl-1-pentene and ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) added during the polymerization reaction. By using such a polymer, it is possible to obtain sheet-like cotton having excellent heat retention and texture.

<Requirements (A-II)>
The 4-methyl-1-pentene polymer (A) preferably has a density of 820 to 850 kg/m ³ , more preferably 825 to 845 kg/m ³ , still more preferably 830 to 840 kg/m ³ , and particularly preferably 830 to 835 kg/m ³ , as measured according to JIS K7112:1999 (density gradient tube method).
Fibers using the 4-methyl-1-pentene polymer (A) having a density satisfying the above range are excellent in lightness.

<Requirements (A-III)>
The 4-methyl-1-pentene polymer (A) has a melting point (Tm) measured by a differential scanning calorimeter (DSC) of preferably 200 to 260°C, more preferably 210 to 250°C, still more preferably in the range of 215 to 245°C.
When the melting point (Tm) is within the above range, fibers with excellent heat resistance can be obtained, and sheet-like cotton with excellent heat retention and texture can be obtained.

In addition, the 4-methyl-1-pentene polymer (A) usually has a heat of fusion measured by a differential scanning calorimeter (DSC) of preferably 50 J/g or less, more preferably 10 to 50 J/g, still more preferably 15 to 45 J/g, and particularly preferably in the range of 20 to 40 J/g.

When the heat of fusion is within the above range, the crimpability of the fibers is enhanced, and the obtained sheet-like cotton is excellent in heat retention and texture. The heat of fusion of the 4-methyl-1-pentene polymer (A) can be arbitrarily adjusted by appropriately selecting the comonomer species and its amount.

The 4-methyl-1-pentene polymer (A) usually has an intrinsic viscosity [η] _A measured in decalin at 135°C, preferably in the range of 1.35 to 2.20 dl/g, more preferably 1.40 to 2.20 dl/g, and still more preferably 1.45 to 1.90 dl/g. When the intrinsic viscosity [η] _A is within the above range, the crimpability of the obtained fiber is enhanced, and the obtained sheet-like cotton is excellent in heat retention and texture.

<<(b) area>>
Region (b) consists of a 4-methyl-1-pentene polymer (B) having an MFR (B) (260° C., 5.0 kg load) in the range of more than 180 g/10 min and 400 g/10 min or less.

[4-methyl-1-pentene polymer (B)]
The 4-methyl-1-pentene polymer (B) has an MFR (B) measured at 260° C. and 5.0 kgf (kg load) (hereinafter simply referred to as “MFR (B)”) of more than 180 g/10 min and 400 g/10 min or less, preferably 200 to 400 g/10 min, more preferably 230 to 380 g/min, and even more preferably 250 to 350. It is in the range of g/10min.

When the MFR (B) is within the above range, fibers with excellent spinnability and crimpability can be obtained, and sheet-like cotton with excellent heat retention and texture can be obtained. Further, when the MFR (B) of the 4-methyl-1-pentene polymer (B) is within the above range, it becomes easy to set the ratio (MFR (A)/MFR (B)) to the MFR (A) of the 4-methyl-1-pentene polymer (A), which is one of the components constituting the fiber, within the range of 0.10 to 0.65.

The 4-methyl-1-pentene-based polymer (B) preferably satisfies the following requirements (BI) to (B-III) from the viewpoint that the resulting cotton sheet has excellent heat retention and texture.

<Requirements (B-I)>
In the 4-methyl-1-pentene polymer (B), the content (U3) of structural units derived from 4-methyl-1-pentene is preferably 100 to 90.0 mol%, more preferably 100 to 93.0 mol%, still more preferably 99.5 to 95.0 mol%, and the content of structural units derived from ethylene and an α-olefin having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene). (U4) is preferably in the range of 0 to 10.0 mol%, more preferably 0 to 7.0 mol%, still more preferably 0.5 to 5.0 mol%. However, the total amount of (U3) and (U4) is 100 mol %.

When the 4-methyl-1-pentene polymer (B) is a copolymer, ethylene, propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4,4-dimethyl-1-pentene, 4-methyl-1-hexene, 4 , 4-dimethyl-1-hexene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene. Among these, preferred are ethylene, propylene, 1-butene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene and 1-octadecene. More preferred are 1-hexene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-hexadecene and 1-octadecene. These α-olefins may be used singly or in combination of two or more.

Structural units derived from 4-methyl-1-pentene in the 4-methyl-1-pentene-based polymer (B), and ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) The amount of structural units derived from ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) can be adjusted by adjusting the amounts of 4-methyl-1-pentene and ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) added during the polymerization reaction. By using such a polymer, it is possible to obtain fibers having excellent crimpability and to obtain sheet-like cotton excellent in heat retention and texture.

<Requirements (B-II)>
The 4-methyl-1-pentene polymer (B) preferably has a density measured in accordance with JIS K7112:1999 (density gradient tube method) of 820 to 850 kg/m ³ , more preferably 825 to 845 kg/m ³ , still more preferably 830 to 840 kg/m ³ , and particularly preferably 830 to 835 kg/m ³ .
The fiber obtained by using the 4-methyl-1-pentene polymer (B) whose density satisfies the above range is excellent in lightness, and sheet-like cotton excellent in heat retention and texture can be obtained.

<Requirements (B-III)>
In addition to the above requirements, the 4-methyl-1-pentene polymer (B) usually has a melting point (Tm) measured by a differential scanning calorimeter (DSC) of preferably 200 to 260°C, more preferably 210 to 250°C, and still more preferably 215 to 245°C.
When the melting point (Tm) is within the above range, fibers with excellent heat resistance can be obtained, and sheet-like cotton with excellent heat retention and texture can be obtained.

The 4-methyl-1-pentene polymer (B) usually has a heat of fusion measured by a differential scanning calorimeter (DSC) of preferably 30 J/g or more, more preferably 30 to 60 J/g, still more preferably 35 to 55 J/g, and particularly preferably in the range of 40 to 50 J/g.

When the heat of fusion is within the above range, the crimpability of the fibers can be enhanced, and a sheet-like cotton excellent in heat retention and texture can be obtained. The heat of fusion of the 4-methyl-1-pentene polymer (B) can be arbitrarily adjusted by appropriately selecting the comonomer species and its amount.

The 4-methyl-1-pentene polymer (B) usually has a limiting viscosity [η] _B measured in decalin at 135°C of preferably 1.00 to 1.35 dl/g, more preferably 1.05 to 1.35 dl/g, still more preferably 1.05 to 1.30 dl/g, and particularly preferably 1.10 to 1.25 dl/g. When the intrinsic viscosity [η] _B is within the above range, the crimpability of the resulting fiber can be enhanced, and a sheet-like cotton excellent in heat retention and texture can be obtained.

<MFR(A)/MFR(B)>
The ratio of MFR (A) to MFR (B) (MFR (A)/MFR (B)) is preferably 0.10 to 0.65, more preferably 0.13 to 0.63, still more preferably 0.15 to 0.60, and particularly preferably 0.18 to 0.50.
When the MFR ratio (MFR(A)/MFR(B)) of the 4-methyl-1-pentene-based polymer (A) and the 4-methyl-1-pentene-based polymer (B) is within the above range, melt spinning can be easily performed, a fiber having excellent crimpability can be obtained, and a sheet-like cotton having excellent heat retention and texture can be obtained.

The structure of the fiber (X) contained in the sheet-like cotton according to the present invention is not particularly limited as long as it can be used as a sheet-like cotton, and examples thereof include side-by-side type conjugate fibers and eccentric core-sheath type conjugate fibers. Composite fibers having a crimped structure of at least one of a side-by-side type and an eccentric core-sheath type are preferred from the viewpoint of excellent heat retention and texture of the obtained sheet-like cotton.

The shape of the crimped structure is not particularly limited, and may be a wavy crimped structure, a spiral crimped structure, or a crimped structure in which these are mixed. The conjugate fiber having a crimped structure may be obtained by self-crimping the fiber (X), or mechanically crimping the fiber (X).

A "side-by-side type conjugate fiber" refers to a fiber obtained by bonding at least two kinds of resins by melt extrusion, arranging them in the in-plane direction of the bonded surfaces, and spinning them. The cross section of the side-by-side type fiber has a region composed of at least two types of resin, and the area ratio in that region is mainly determined by the resin extrusion ratio during melt extrusion.

The term “eccentric sheath-core composite fiber” refers to a fiber in which the center of gravity of the inner layer is different from the center of gravity of the entire fiber in the cross-sectional shape of the core-sheath fiber, and is produced using a composite nozzle arranged such that the center of gravity of the inner layer is different from the center of gravity of the entire fiber, such as an eccentric core-sheath composite nozzle. In addition, the cross section of the eccentric core-sheath type conjugate fiber has regions composed of at least two kinds of resins, and the area ratio in these regions is mainly determined by the extrusion ratio of the resins during melt extrusion.

Among these, the above fibers are preferably conjugate fibers having a side-by-side crimped structure from the viewpoint of obtaining a sheet-like cotton having higher crimpability and excellent heat retention and texture. Further, from the viewpoint of obtaining a sheet-like cotton excellent in crimpability and spinnability, heat retention and texture, conjugate fibers having an eccentric core-sheath crimp structure are preferred.
When the fiber is a composite fiber having an eccentric core-sheath crimped structure, it is preferable that the core component is the polymer (B) and the sheath component is the polymer (A).

The eccentricity of the core component is preferably in the range of 20-85%, more preferably in the range of 30-80%, and particularly preferably in the range of 40-75%. The eccentricity here is defined by the following equation.
Eccentricity (%) = (Distance between the center of the composite fiber cross section and the center of the core component cross section)
/ Radius of composite fiber x 100

The cross-sectional shape (peripheral shape) of the fiber is not particularly limited, and can be appropriately selected according to the application and required properties. In the case of eccentric sheath-core conjugate fibers, the cross-sectional shape is usually a perfect circle.

<<Fiber length>>
The fibers (X) contained in the sheet-like cotton have a fiber length of 40 mm or less. The fiber length of the fibers (X) is preferably 20 mm or more and 40 mm or less, more preferably 25 mm or more and 38 mm or less, from the viewpoint of obtaining a sheet-like cotton excellent in heat retention and texture.

The content of the fiber (X) is 40% by mass or more and less than 95% by mass with respect to the total mass of the cotton sheet. From the viewpoint that a cotton sheet having excellent heat retention and texture can be obtained more easily, the content of the fiber (X) is preferably 50 to 93% by mass, more preferably 60 to 90% by mass, still more preferably 70 to 90% by mass, and particularly preferably 80 to 90% by mass, relative to the total mass of the cotton sheet.

<<Method for producing fiber (X)>>
The method for producing the fiber (X) is not particularly limited, and known production methods can be used. For example, the 4-methyl-1-pentene-based polymer (A) and the 4-methyl-1-pentene-based polymer (B) are separately melted using two extruders and extruded from a composite spinneret to obtain fibers. After cooling, stretching, thinning and crimping the fibers, a process of depositing the fibers on a collection belt to a predetermined thickness, and a winding process can be adopted.

[Method for producing eccentric sheath-core composite fiber]
When the fiber is an eccentric sheath-core composite fiber, the method for producing the fiber (X) preferably includes a step of supplying and spinning the 4-methyl-1-pentene-based polymer (A) and the 4-methyl-1-pentene-based polymer (B) from the sheath component injection nozzle and the core component injection nozzle of the eccentric sheath-core composite nozzle.
A specific example of a method for producing an eccentric sheath-core type composite fiber will be described in detail below.
First, the 4-methyl-1-pentene-based polymer (A) and the 4-methyl-1-pentene-based polymer (B) are separately melted in a melt spinning machine and weighed with a metering pump, then the polymer (A) is supplied to the sheath component injection nozzle of the eccentric sheath-core composite nozzle, the polymer (B) is supplied from the core component injection nozzle, and the resin discharge amounts of the core and the sheath of the eccentric sheath-core composite nozzle are adjusted to adjust the mass fraction of the sheath component and the content of the core component. is controlled to obtain a spun yarn. The obtained spun yarn is cooled and solidified by a cooling device, then oiled and entangled by an entangling device. Thereafter, the spun yarn is taken up by a godet roll and wound by a winder to form a wound yarn (eccentric core-sheath type composite fiber).

The melt spinning machine is not particularly limited as long as it can spin, and examples thereof include an extruder type and a pressure melter type. In order to improve spinning operability, productivity, and mechanical properties of the fiber, a heating cylinder or a heat retaining cylinder having a length of 2 to 20 cm may be installed under the spinneret, if necessary.

The spinning temperature in the melt spinning is preferably 260-320°C. When the spinning temperature is 260° C. or higher, the elongation viscosity of the spun yarn discharged from the spinneret is sufficiently lowered, so that the discharge is stable, and furthermore, the spinning tension does not become excessively high, and yarn breakage can be suppressed, which is preferable. The spinning temperature is more preferably 270°C or higher, even more preferably 280°C or higher. On the other hand, if the spinning temperature is 320° C. or lower, thermal decomposition during spinning can be suppressed, and the obtained conjugate fiber does not suffer from poor mechanical properties or coloration, which is preferable. The spinning temperature is more preferably 310°C or lower, even more preferably 300°C or lower.

The spinning speed in melt spinning can be appropriately selected according to the spinning temperature, the composite ratio of the 4-methyl-1-pentene polymer (A) and the 4-methyl-1-pentene polymer (B), etc., and is preferably 300 to 3000 m/min. A spinning speed of 800 m/min or more is preferable because the running yarn is stabilized and yarn breakage can be suppressed. The spinning speed is more preferably 1000 m/min or higher, and even more preferably 1500 m/min or higher. On the other hand, a spinning speed of 3000 m/min or less is preferable because the spun yarn can be sufficiently cooled and stable spinning can be performed. The spinning speed is more preferably 2750 m/min or less, even more preferably 2500 m/min or less.

The undrawn yarn drawn by melt spinning is preferably drawn from the viewpoint of obtaining a conjugate fiber having desired fiber properties. The drawing method is not particularly limited, and includes, but is not limited to, a two-step method of drawing an undrawn yarn once wound on a drum, a direct spinning drawing method of continuously drawing without winding on a drum, and the like.

A heating method for drawing is not particularly limited as long as it is an apparatus capable of directly or indirectly heating the running yarn. Specific examples of the heating method include, but are not limited to, devices such as heating rollers, hot pins, hot plates, and lasers, liquid baths such as hot water and hot water, and gas baths such as hot air and steam. These heating methods may be used alone or in combination. As a heating method, from the viewpoint of controlling the heating temperature, uniform heating of the running yarn, and not complicating the apparatus, contact with a heating roller, contact with a hot pin, contact with a hot plate, and immersion in a liquid bath such as hot water or hot water can be suitably adopted.

The draw ratio when drawing is performed can be appropriately selected depending on the composite ratio of the 4-methyl-1-pentene polymer (A) and the 4-methyl-1-pentene polymer (B), the strength and elongation of the composite fiber after drawing, and is preferably 1.1 to 3.5 times. A draw ratio of 1.1 times or more is preferable because the mechanical properties such as strength and elongation of the composite fiber can be improved by drawing. The draw ratio is more preferably 1.2 times or more, and still more preferably 1.3 times or more. On the other hand, if the draw ratio is 3.5 times or less, yarn breakage during drawing is suppressed, and stable drawing can be performed, which is preferable. The draw ratio is more preferably 3.2 times or less, and even more preferably 3.0 times or less. Either a one-step drawing method or a multi-step drawing method with two or more steps may be used.

The drawing temperature for drawing can be appropriately selected according to the strength and elongation of the conjugate fiber after drawing, but it is preferably 80 to 140°C. If the drawing temperature is 80° C. or higher, the yarn supplied for drawing is sufficiently preheated, thermal deformation during drawing becomes uniform, and unevenness in fineness can be suppressed, which is preferable. The stretching temperature is more preferably 85° C. or higher, even more preferably 90° C. or higher. On the other hand, if the drawing temperature is 140° C. or lower, yarn breakage during drawing is suppressed, and stable drawing can be performed, which is preferable. The stretching temperature is more preferably 135° C. or lower, even more preferably 130° C. or lower. Further, if necessary, heat setting at 80 to 150° C. may be performed after stretching.

[Method for producing side-by-side composite fiber]
When the conjugate fiber is a side-by-side type conjugate fiber, the method for producing the fiber (X) preferably includes a step of disposing the 4-methyl-1-pentene-based polymer (A) and the 4-methyl-1-pentene-based polymer (B) side-by-side and spinning them. An example of a method for producing a side-by-side type composite fiber is shown below.
The side-by-side type conjugate fiber can be obtained, for example, by using a side-by-side type composite nozzle in the above-described "step of individually melting the 4-methyl-1-pentene polymer (A) and the 4-methyl-1-pentene polymer (B) using two extruders and extruding them from a composite spinneret to obtain a conjugate fiber", The 4-methyl-1-pentene-based polymer (A) and the 4-methyl-1-pentene-based polymer (B) are laminated side-by-side and discharged to obtain a spun yarn, but the above-described eccentric core-sheath type composite fiber can be manufactured by the same method as the manufacturing method.

<Fiber (Y)>
The sheet-like cotton according to the present invention contains fibers (Y) made of one or more resins selected from the group consisting of polyester, polyamide, thermoplastic polyacrylonitrile, thermoplastic polyurethane, polypropylene, polyethylene and cellulose derivatives.
The sheet-like cotton contains fibers (Y), thereby making it easier to form the sheet-like cotton.

The polyester is not particularly limited, and examples thereof include aromatic polyesters such as polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polyhexamethylene terephthalate; A copolymerized polyester obtained by copolymerizing a copolymer component with a polyester may be mentioned.

Specific examples of copolymer components of polyester include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, 5-sodium sulfoisophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,2'-biphenyldicarboxylic acid, 3,3'-biphenyldicarboxylic acid, 4,4'-biphenyldicarboxylic acid, anthracenedicarboxylic acid, malonic acid, fumaric acid, maleic acid, succinic acid, and itaconic acid. , adipic acid, azelaic acid, sebacic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, aliphatic dicarboxylic acids such as dimer acid, aromatic diols such as catechol, naphthalenediol and bisphenol, ethylene Glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, neopentyl glycol, aliphatic diols such as cyclohexanedimethanol, and the like, but are not limited thereto. These copolymer components may be used alone or in combination of two or more.

The polyamide is not particularly limited, and examples thereof include aromatic polyamides such as nylon 6T, nylon 9T, and nylon 10T; aliphatic polyamides such as nylon 4, nylon 6, nylon 11, nylon 12, nylon 46, nylon 410, nylon 66, and nylon 610; and copolymerized polyamides obtained by copolymerizing these polyamides with copolymer components.

Specific examples of copolymer components of polyamides include aromatic diamines such as metaphenylenediamine, paraphenylenediamine, metaxylylenediamine and paraxylylenediamine, 1,2-ethylenediamine, 1,3-trimethylenediamine, 1,4-tetramethylenediamine, 1,5-pentamethylenediamine, 2-methyl-1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9 Aliphatic diamines such as -nonamethylenediamine, 2-methyl-1,8-octamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine, 1,13-tridecamethylenediamine, 1,16-hexadecamethylenediamine, 1,18-octadecamethylenediamine, 2,2,4-trimethylhexamethylenediamine, piperazine, cyclohexanediamine, phthalic acid, isophthalic Aromatic dicarboxylic acids such as acids, terephthalic acid, 5-sodium sulfoisophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,2'-biphenyldicarboxylic acid, 3,3'-biphenyldicarboxylic acid, 4,4'-biphenyldicarboxylic acid, anthracenedicarboxylic acid, malonic acid, fumaric acid, maleic acid, succinic acid, itaconic acid, adipic acid, azelaic acid, sebacic acid, 1,11 -undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, aliphatic dicarboxylic acids such as dimer acid, and the like, but are not limited thereto. These copolymer components may be used alone or in combination of two or more.

Thermoplastic polyacrylonitrile includes copolymers of acrylonitrile and copolymerization components.
Specific examples of copolymer components of thermoplastic polyacrylonitrile include, for example, acrylic acid esters such as methyl acrylate, ethyl acrylate, propyl acrylate and butyl acrylate; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate and butyl methacrylate; haloolefins such as vinyl chloride, vinyl fluoride, vinylidene chloride and vinylidene fluoride; vinylamides such as acrylamide, methacrylamide and vinylpyrrolidone; vinyl aromatic compounds such as vinyl esters such as styrene and vinylpyridine; vinyl carboxylic acids such as acrylic acid and methacrylic acid; vinyl sulfonic acids such as p-styrenesulfonic acid, allylsulfonic acid and methallylsulfonic acid; These copolymer components may be used alone or in combination of two or more.

The thermoplastic polyurethane is not particularly limited, and may be a polymer compound obtained by reaction of three components: diisocyanate, polyol, and chain extender.
Specific examples of diisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, 1,3-cyclohexanediisocyanate, 1,4-cyclohexanediisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,5-diisocyanate Examples include, but are not limited to, phthalene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane diisocyanate, and the like.

Examples of polypropylene include homopolymers of propylene and copolymers having propylene as the main monomer. In the case of a copolymer, it may be a random copolymer or a block copolymer. Monomers to be copolymerized with propylene include α-olefins other than propylene, diene compounds, and the like.

Polyethylene is not particularly limited, and examples thereof include homopolymers of ethylene and copolymers of ethylene and α-olefins having 3 or more carbon atoms. Examples of α-olefins having 3 or more carbon atoms to be copolymerized with ethylene include α-olefins having 3 to 20 carbon atoms such as propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene and 1-tetradecene. Polyethylene may be low density polyethylene or high density polyethylene. The low density polyethylene may be high pressure low density polyethylene or linear low density polyethylene.

A cellulose derivative is a compound in which at least part of the three hydroxyl groups present in glucose, which is a constituent unit of cellulose, is derivatized to another functional group.
The cellulose derivative is not particularly limited. Examples thereof include cellulose single esters in which one type of ester group is bonded to cellulose, cellulose mixed esters in which two or more types of ester groups are bonded, cellulose single ethers in which one type of ether group is bonded, cellulose mixed ethers in which two or more types of ether groups are bonded, cellulose ether esters in which one or more types of ether groups and ester groups are bonded, and the like.
The degree of substitution of the cellulose derivative is not particularly limited, and can be appropriately selected depending on the melt viscosity, thermoplasticity, and the like. Moreover, when the cellulose derivative does not exhibit thermoplasticity, a plasticizer may be added to the cellulose derivative for the purpose of improving thermal fluidity.

Specific examples of cellulose derivatives include cellulose monoesters such as cellulose acetate, cellulose propionate, cellulose butyrate, cellulose valerate and cellulose stearate, cellulose mixed esters such as cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate valerate, cellulose acetate caproate, cellulose propionate butyrate, cellulose acetate propionate butyrate, methyl cellulose, ethyl cellulose, propyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl. Cellulose, cellulose single ethers such as carboxymethylcellulose, cellulose mixed ethers such as methylethylcellulose, methylpropylcellulose, ethylpropylcellulose, hydroxymethylmethylcellulose, hydroxymethylethylcellulose, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, etc., methylcellulose acetate, methylcellulose propionate, ethylcellulose acetate, ethylcellulose propionate, propylcellulose acetate, propylcellulose propionate, hydroxymethylcellulose acetate, hydroxymethylcellulose propionate, hydroxyethylcellulose acetate, hydroxyethylcellulose propionate. Cellulose ether esters such as pionate, hydroxypropyl cellulose acetate, hydroxypropyl cellulose propionate, carboxymethyl cellulose acetate, carboxymethyl cellulose propionate, and the like, but are not limited thereto.

From the viewpoint of making it easier to form a cotton sheet and obtaining a cotton sheet excellent in heat retention and texture, the fiber (Y) is more preferably a fiber made of at least one resin selected from the group consisting of polyester, polypropylene and polyethylene, more preferably a polyester fiber, and particularly preferably a polyethylene terephthalate fiber.

The fiber (Y) may be a single fiber, or may be another composite fiber composed of two or more resins selected from the above resins. Other conjugate fibers may be, for example, core-sheath type conjugate fibers or split type conjugate fibers.

<<Fiber length>>
The fiber length of the fibers (Y) contained in the sheet-like cotton is not particularly limited and can be set as appropriate. The fiber length of the fiber (Y) is preferably 20 mm or more and 40 mm or less, more preferably 25 mm or more and 38 mm or less, from the viewpoint that sheet-like cotton is easily obtained.

The content of the fiber (Y) is more than 5% by mass and 60% by mass or less with respect to the total mass of the cotton sheet, and from the viewpoint of obtaining a cotton sheet with excellent heat retention and texture, the content is preferably 7 to 50% by mass, more preferably 10 to 40% by mass, further preferably 10 to 30% by mass, particularly preferably 10 to 20% by mass.

The sheet-like cotton according to the present invention may further contain fibers other than the fibers (X) and (Y) (hereinafter also referred to as "other fibers") within a range that does not impair the effects of the present invention.
Other fibers include, for example, natural fibers such as cotton, silk, wool, hemp and pulp, and fibers other than fiber (Y) such as rayon and cupra.

The other fibers may be single fibers or other composite fibers made of two or more resins selected from the above resins. Other conjugate fibers may be, for example, core-sheath type conjugate fibers or split type conjugate fibers.
The content of other fibers is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, and particularly preferably not substantially contained, based on the total mass of the cotton sheet, from the viewpoint of obtaining a sheet-like cotton excellent in lightness.

(Manufacturing method of sheet cotton)
The method for producing sheet-like cotton according to the present invention preferably includes a step of combining and melt-spinning the polymer (A) and the polymer (B), and a step of forming the obtained fibers into a sheet (sheeting step).

<<Melt spinning process>>
The step of combining and melt-spinning the polymer (A) and the polymer (B) (melt spinning step) is preferably a step of melting the 4-methyl-1-pentene-based polymer (A) and the 4-methyl-1-pentene-based polymer (B) separately using two extruders, discharging them from a composite spinneret, and melt-spinning the 4-methyl-1-pentene-based polymer (A) and the 4-methyl-1-pentene-based polymer ( B) is individually melted using two extruders, and the polymer (A) and the polymer (B) are supplied to the sheath component injection nozzle and the core component injection nozzle of the eccentric core-sheath type composite nozzle, respectively, and melt-spun.
The melt-spinning step has the same meaning as each step in the method for producing the fiber (X), and preferred embodiments are also the same.

<<Sheet process>>
The sheeting method in the step of sheeting the melt-spun (sheeting step) is not particularly limited and includes known sheeting methods. The sheet forming step includes, for example, a step of forming a fiber web from the fibers obtained in the above step with a carding machine.

<<Other processes>>
The method for producing sheet-like cotton may further include processes other than the melt-spinning process and the sheet-forming process (hereinafter referred to as "other processes").
Other steps include a step of cutting the fibers obtained in the melt spinning step, a step of mixing the obtained fibers with other fibers, and a step of opening the obtained fibers. It is preferable to have these steps before the sheeting step.

The thickness of the obtained cotton sheet is preferably 1 mm to 15 mm, more preferably 2 mm to 13 mm, from the viewpoint of obtaining a cotton sheet excellent in heat retention and texture. The basis weight of the cotton sheet is preferably 50 g/m ² to 150 g/m ² from the viewpoint of obtaining a cotton sheet excellent in heat retention and texture.

(Fiber products)
A textile product according to the present invention includes the above sheet-like cotton. The textile product may be either a woven fabric or a non-woven fabric. From the viewpoint of excellent heat retention and texture, the textile product preferably includes a side fabric and a filling, and the filling includes a filling formed from the sheet-like cotton. More preferably, the side fabric and the filling are a side fabric formed from the sheet-like cotton and a filling formed from the sheet-like cotton.

In textile products, for example, the above-mentioned sheet-like cotton may be used as it is as a batting, or may be used as a batting in the form of a laminate composed of a plurality of sheet-like cottons. In addition, in the batting containing this sheet-like cotton, the fibers may be bonded together. Sheet-like cotton is preferable because when it is used as a filling for textile products, the filling is less likely to be biased inside the product.

The textile product may have a construction in which the filling is between the two side materials of the outer material and the lining (side material/filling/lining construction) or a construction in which the outer material is the side material and the filling (lining material/filling construction), but it is preferable to have a construction in which the filling is provided between the two side materials of the outer material and the lining material. When the side material consists of two sheets, the outer material and the lining material, the outer material and the lining material may be the same or different. Also, the side fabric may be composed of one piece of cloth, or may be composed of two or more pieces of cloth. Also, the filling may be one layer, or may be a laminate of two or more layers.

The textile may further include quilt stitches. That is, in the textile product, at least a part of the side fabric and the filling may be fixed by quilt stitches using threads. Threads made of natural fibers or synthetic fibers can be used for quilt stitching without any particular restrictions, but it is more preferable to use threads made of fibers containing a 4-methyl-1-pentene polymer. When a yarn made of a fiber containing a 4-methyl-1-pentene polymer is used for the quilt stitches, the side fabric, the batting and the quilt stitches are all made of the 4-methyl-1-pentene polymer, which is preferable because it has excellent recyclability.

Since both the side fabric and the filling are made of fibers containing a 4-methyl-1-pentene polymer, the textile product has a low density and is lightweight, has high heat retention, has excellent texture and stain resistance, and has good dehydration and drying properties when it contains water during washing. In addition, the textile product has excellent heat resistance because both the side material and the filling material are made of the above-mentioned sheet-like cotton, and is excellent in recyclability because the side material and the filling material are made of the same material.

The textile product can be used in various applications without limitation, and can be suitably used in applications where known quilt fabrics and the like are used. For example, the textile product contains a side material and filling, and is suitable for blankets; rugs; bedding such as comforters, sleeping bags, and pillows;
The textile product is preferably used for blankets, rugs, bedding, cushions, mats, or clothing from the viewpoint of excellent heat retention and texture.
In addition, the textile product is suitable for use as a cushioning material, a sound absorbing material, a sound insulating material, a vibration insulating material, a heat insulating material, a heat insulating material, or the like, by including the side material and the batting.

EXAMPLES The present invention will be described in more detail based on examples below, but the present invention is not limited to these examples.

[Production Example 1]
Production of 4-methyl-1-pentene/1-decene copolymer (A-1) (polymer (A)) In Comparative Example 7 of International Publication No. 2006/054613, the amount of monomer charged was changed so that the content of structural units derived from 4-methyl-1-pentene and 1-decene in the obtained copolymer was the content shown in Table 1 below, and the amount of hydrogen during polymerization was changed so that the melt flow rate (MFR) shown in Table 1 below was obtained. A 4-methyl-1-pentene/1-decene copolymer (A-1) was obtained by the adjustment.

[Production Example 2]
Production of 4-methyl-1-pentene/1-decene copolymer (B-1) In Comparative Example 7 of International Publication No. 2006/054613, the amount of monomer charged was changed so that the content of structural units derived from 4-methyl-1-pentene and 1-decene in the obtained copolymer was as shown in Table 1 below, and the amount of hydrogen during polymerization was adjusted or kneaded and melted so that the melt flow rate (MFR) was as shown in Table 1 below. Thus, a 4-methyl-1-pentene/1-decene copolymer (B-1) was obtained.

<Method for producing fiber (X)>
The 4-methyl-1-pentene/1-decene copolymer (A-1) and the 4-methyl-1-pentene/1-decene copolymer (B-1) obtained above were melted at 290° C. using separate extruders, weighed with a metering pump, and sent to a spinning pack built into the spinning block. After filtering in the spinning pack, the spinning temperature is 290 ° C. ) () (Cross -sectional area ratio) was 60/40, and a disgusting core sheath type composite fibers were produced as a disorder rate of 73 %. The obtained eccentric sheath-core conjugate fibers were cooled by a cooling device, solidified, and oiled by a lubricating device, then taken up by a first godet roll, passed through a second godet roll, a third godet roll and a fourth godet roll, and wound by a winder to obtain eccentric sheath-core conjugate fibers shown in Table 2. The obtained conjugate fiber was cut to a fiber length of 38 mm.

When the cross section of the obtained conjugate fiber was observed with a laser microscope (magnification × 100), it was confirmed to have two regions, the (a) region composed of the 4-methyl-1-pentene/1-decene copolymer (A-1) and the (b) region composed of the 4-methyl-1-pentene/1-decene copolymer (B-1).

<Method for producing fiber (Y)>
Polyethylene terephthalate (PET) was melted by an extruder, discharged from a round-hole nozzle, cooled and solidified by a cooling device, and then oiled by an oiling device. The fibers were then drawn, crimped with a crimper, and heat set to obtain polyethylene terephthalate fibers shown in Table 2. The fibers obtained were cut to a fiber length of 38 mm.

<Fineness>
The fineness was measured according to JIS L1013:2010.

<Number of crimps and crimp rate>
The number of crimps and the crimp ratio were measured in accordance with JIS L1015:2010 using the fiber obtained by the method for producing the fiber (X) or the fiber (Y) as a measurement sample.
The distance (space distance) (mm) between the grips of the crimp tester when an initial load (0.18 mN×sample fineness) was applied to the measurement sample was read to determine the number of crimps per inch. The number of crimps was obtained by counting all the peaks and valleys and dividing the number by two.
The crimp rate was calculated by the following formula from the length when an initial load of 1.8 mN x sample fineness (dtex) was applied to the sample and the length when a load of 4.41 mN x sample fineness (dtex) was applied.
C=(ba)×100/b
C: Crimp rate (%)
a: Length when initial load is applied (mm)
b: Length (mm) when a load of 4.41 mN x sample fineness (dtex) is applied

[Example 1]
The fiber (X) and the fiber (Y) obtained above were each passed through a carding machine to open the fibers, and the content of the fiber (X) was 85% by ^mass and the content of the fiber (Y) was 15% by mass based on the total mass of the cotton sheet.

[Example 2]
The fibers (X) and (Y) obtained above ^were each passed through a carding machine to open the fibers, and the fiber (X) content was 50% by mass and the fiber (Y) content was 50% by mass relative to the total mass of the cotton sheet.

[Comparative Example 1]
The fibers (X) and (Y) obtained above were passed through a ^carding machine to open the fibers, and the fiber (X) content was 95% by mass and the fiber (Y) content was 5% by mass. Since the sheet-like cotton could not be produced, the subsequent evaluation of the sheet-like cotton could not be performed.

[Comparative Example 2]
The fibers (Y) obtained above (that is, the content of the fibers (Y) is 100% by mass) were passed through a carding machine to open the fibers, and processed into a cotton sheet having a basis weight of 100 g/m ² to produce a cotton sheet having a thickness of 5 mm.

<Heat retention rate, heat retention rate around thickness, and heat retention evaluation>
Using the sheet-shaped cotton obtained in Examples 1 and 2 and Comparative Example 2 as samples, the heat retention rate was determined using an ASTM type heat retention tester at a room temperature of 20 ° C. and 65% RH in accordance with JIS L1096:2010 8.27 A method (constant temperature method).
That is, first, the amount of heat a (J/cm ² ·s) radiated after 2 hours without setting the test piece on a hot plate set at a constant temperature was measured. Next, a test piece taken from the sample was set on a hot plate, and the amount of heat b (J/cm ² ·s) radiated through the test piece was measured after 2 hours.
From the values of heat quantity a and heat quantity b obtained above, heat retention rate (%) was obtained using the following formula.
Heat retention rate (%) = (1-b/a) x 100

The heat retention rate (%) obtained by the above formula was divided by the thickness of the cotton sheet to obtain the heat retention rate (%/mm) around the thickness.
Based on the results obtained above, heat retention was evaluated according to the following criteria. Evaluation results are shown in Table 3. It can be said that the heat retaining property is excellent when the heat retaining rate per thickness is 15% or more.

-Evaluation criteria for heat retention-
A: Thermal insulation rate ≥ 15% per thickness
B: Thermal insulation rate per thickness <15%

<Texture evaluation>
10 test subjects were asked to touch the cotton sheet, and the feel was evaluated according to the following criteria for the number of people who judged that the cotton sheet was soft. If the evaluation criteria for the texture are A and B, it can be said that the texture is excellent. Evaluation results are shown in Table 3.

-Evaluation criteria for texture-
A: Judged as soft by 8 or more B: Judged as soft by 5 or more but less than 8 C: Judged as soft by less than 5

In Table 3, "not evaluated" means that the cotton sheet could not be produced and the evaluation of the cotton sheet could not be carried out. In Table 3, "Possible" in the column of sheet-like cotton means that sheet-like cotton could be produced, and "Not possible" means that sheet-like cotton could not be produced.
It can be seen that the cotton sheets of Examples 1 and 2 are superior to the cotton sheet of Comparative Example 2 in heat retention and texture.

Claims (8)

a fiber (X) having a cross section of at least two regions (a) and (b) below and having a fiber length of 40 mm or less;
Fibers (Y) made of one or more resins selected from the group consisting of polyester, polyamide, thermoplastic polyacrylonitrile, thermoplastic polyurethane, polypropylene, polyethylene and cellulose derivatives;
including
Sheet cotton, wherein the content of the fiber (X) is 40% by mass or more and less than 95% by mass with respect to the total mass of the sheet cotton, and the content of the fiber (Y) is more than 5% by mass and 60% by mass or less with respect to the total mass of the sheet cotton;
(a) region: MFR (A) (260° C., 5.0 kg load) consisting of a 4-methyl-1-pentene polymer (A) in the range of 30 to 180 g/10 min;
(b) Region: MFR (B) (260° C., 5.0 kg load) consists of a 4-methyl-1-pentene polymer (B) in the range of over 180 g/10 min and 400 g/10 min or less. The cotton sheet according to claim 1, wherein the ratio of said MFR(A) to said MFR(B) (MFR(A)/MFR(B)) is from 0.10 to 0.65. The sheet-like cotton according to claim 1 or 2, wherein the fibers are at least one type of side-by-side type and eccentric core-sheath type conjugate fibers having a crimped structure. The 4-methyl-1-pentene polymer (A) satisfies the following requirements (AI) to (A-III),
The cotton sheet according to any one of claims 1 to 3, wherein the 4-methyl-1-pentene polymer (B) satisfies the following requirements (BI) to (B-III);
(AI) The content (U1) of structural units derived from 4-methyl-1-pentene is 100 to 90.0 mol%, and the content (U2) of structural units derived from olefins selected from the group consisting of ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) is 0 to 10.0 mol%;
(A-II) Density measured according to JIS K7112 (density gradient tube method) is in the range of 820 to 850 kg/m ³ ;
(A-III) a melting point (Tm) of 200° C. to 260° C. as measured by a differential scanning calorimeter (DSC);
(BI) the content (U3) of structural units derived from 4-methyl-1-pentene is 100 to 90.0 mol%, and the content (U4) of structural units derived from ethylene and an α-olefin having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) is 0 to 10.0 mol%;
(B-II) Density measured according to JIS K7112 (density gradient tube method) is in the range of 820 to 850 kg/m ³ ;
(B-III) It has a melting point (Tm) of 200° C. to 260° C. as measured by a differential scanning calorimeter (DSC). A method for producing the cotton sheet according to any one of claims 1 to 4,
A 4-methyl-1-pentene polymer (A) having an MFR (A) measured at 260° C. and 5.0 kgf in the range of 30 to 180 g/10 min and a 4-methyl-1-pentene polymer (B) having an MFR (B) measured at 260° C. and 5.0 kgf in a range of more than 180 g/10 min and not more than 400 g/10 min are combined and melt-spun. process and
a step of sheeting the fibers;
A method for producing sheet-like cotton. A textile product comprising the sheet-shaped cotton according to any one of claims 1 to 4. 7. The textile product of claim 6, which is a blanket, rug, bedding, cushion, mat or garment. 7. The textile product according to claim 6, which is a cushioning material, a sound absorbing material, a sound insulating material, a vibration isolating material, a heat insulating material, or a heat retaining material.