JP7112632B2 - Composite fibers and batting - Google Patents

Description

TECHNICAL FIELD The present invention relates to a composite fiber and a fiber assembly using the composite fiber, particularly batting.

BACKGROUND ART Various filling materials made of synthetic fibers have been proposed for clothing, bedding, stuffed animals, cushion materials, heat insulating materials, and the like. For example, Patent Document 1 proposes a batting material composed of two types of latently crimpable polyester composite fibers. Further, Patent Document 2 proposes a batting containing hollow polyester staple fibers and cellulose short fibers.

JP-A-6-280148 JP 2007-125153 A JP-A-2-191720

Fillings using synthetic fibers are more convenient than fillings using natural fibers such as cotton and wool in terms of light weight and handleability, and fillings using feathers are more convenient in terms of animal protection, handleability and cost. more convenient than Therefore, it is expected that synthetic fiber batting will be used in more products in the future. is always in demand.
The present invention focuses on the bulkiness of synthetic fiber batting, and provides a synthetic fiber that can constitute a batting that has a large initial bulk and maintains bulkiness for a long period of time (that is, does not easily sag). intended to

As one embodiment thereof, the present invention provides a first and a second component containing a propylene-α-olefin copolymer,
either one or both of the first component and the second component comprise a polyolefin elastomer;
The first component is a core component, the second component is a sheath component, and an eccentric core-sheath type fiber cross section in which the center of gravity of the first component is deviated from the center of gravity of the fiber, or the first component and the above Having a side-by-side fiber cross section in which the second component is bonded,
In the component containing the polyolefin elastomer, the proportion of the polyolefin elastomer is 10% by mass or more and 30% by mass or less.
Composite fibers are provided. This composite fiber is suitable for constructing batting.

Although the conjugate fiber has a fiber cross-sectional structure that is likely to develop steric crimps, it is made of polypropylene that satisfies a specific molecular weight distribution and a propylene-α-olefin copolymer, particularly a propylene/ethylene copolymer having a specific ethylene content or By combining a propylene/1-butene/ethylene copolymer having a specific ethylene content and a specific butylene content with a polyolefin-based elastomer, excessive steric crimping does not occur. In addition, this conjugate fiber has moderate elasticity and exhibits high resilience against deformation. Thus, the bicomponent fibers can provide batting that is lofty and less susceptible to loss of bulk over time.

1A to 1C are schematic diagrams showing the forms of three-dimensional crimps that can be developed in the conjugate fiber of this embodiment. FIG. 2 is a schematic diagram showing the form of three-dimensional crimp that can be developed in the conjugate fiber of this embodiment. FIG. 3 is a schematic diagram showing the form of mechanical crimping.

(Circumstances leading to the present invention)
In order to obtain a batting that is less likely to decrease in bulk over time (that is, less likely to set), the present inventors have made latent crimpable conjugate fibers as described in Patent Document 1 with a polyolefin-based thermoplastic resin. I considered configuring Polyolefin-based thermoplastic resins, particularly polypropylene, are 1) excellent in heat retention and heat insulation due to the low thermal conductivity of the resin itself, and 2) the density of the resin itself is low, and the same mass of fibers It is suitable for batting because it is considered that a fiber aggregate having a higher bulk and/or a larger number of constituent fibers can be obtained when compared with the aggregate. Specifically, a latent crimpable conjugate fiber obtained by conjugate-spinning a first component made of polypropylene and a second component containing an ethylene-propylene random copolymer as a main component, described in Patent Document 3. was considered to be used as batting.

However, when the composite fiber described in Patent Document 3 is used and the batting is produced by a method of thermally bonding the fibers together with a binder resin, the fiber shrinks due to the heat during thermal bonding, and the fiber has a large number of fine three-dimensional windings. Shrinkage develops, voids between fibers become smaller, and the initial bulk of the batting becomes smaller. That is, when trying to obtain a batting with a predetermined thickness using the composite fibers described in Patent Document 3, it is necessary to use more fibers, which increases the weight of the batting as a whole, resulting in lightness and drape. diminished sexuality. On the other hand, the batting using monofilaments made of only polypropylene has a low initial bulk and a low bulk recovery because the monofilaments of polypropylene hardly exhibit three-dimensional crimps.

Therefore, the present inventors believe that, even if three-dimensional crimping occurs, if the structure is such that the degree of crimping does not become strong, it is possible to obtain a batting that has a large initial bulk and is excellent in cushioning properties and bulk recovery during use. Thought. Then, a specific polypropylene is used as the first component, a propylene-ethylene copolymer is used as the second component, and a polyolefin elastomer is added to the first component and/or the second component to make the fiber cross section three-dimensional. When a conjugate fiber having a structure in which crimping is easily generated was produced, it was found that a batting that had a large initial bulk and was less likely to decrease in bulk over time could be obtained.
The composite fiber of the present embodiment and the batting using the same will be described below.

(Composite fiber)
The conjugate fiber of the present embodiment includes a first component containing polypropylene having a Q value (ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn)) of 3.5 or more and 6.5 or less. , and a second component containing a propylene-α-olefin copolymer having an ethylene content of 1% by mass or more and 15% by mass or less, and either one or both of the first component and the second component comprise a polyolefin elastomer. wherein the first component is the core component, the second component is the sheath component, and the center of gravity of the first component is offset from the center of gravity of the fiber; It is a conjugate fiber having a side-by-side fiber cross section in which are laminated together.

In this embodiment, the first component contains polypropylene having a Q value of 3.5 or more and 6.5 or less. By using a polypropylene having a Q value within this range, it is possible to obtain a conjugate fiber in which steric crimps are less likely to develop excessively. When the Q value is less than 3.5, the degree of steric crimping increases, and when the Q value exceeds 6.5, steric crimping is less likely to occur.

Although the ranges stated herein are for the Q value after spinning, it is preferred that the Q value before spinning also be within the ranges stated herein. The pre-spinning Q value is generally provided by the resin manufacturer. The Q value of polypropylene after spinning is measured for the polypropylene contained in the first component of the conjugate fiber. If it is difficult to measure the Q value of the polypropylene constituting the conjugate fiber, only the polypropylene is spun under the same conditions as the conjugate fiber spinning conditions (the spinning temperature is that of the first component). The Q value of the single fiber obtained by this method may be measured, and the measured value may be used as the Q value of the polypropylene contained in the first component of the present embodiment.

As long as the Q value satisfies the above range, for example, the melting point of the polypropylene before spinning may be in the range of 150 ° C. to 170 ° C., and the melt flow rate (MFR) before spinning is 10 g / 10 minutes. It may be in the range of 60 g/10 minutes or more. The melting point can be obtained from a melting calorie curve obtained by DSC, and the temperature at which the peak is shown (melting peak temperature) is defined as the melting point. The same applies to other resins described below. MFR is measured according to JIS-K-7210 (conditions: 230 ° C., load 21.18 N (2.16 kg). When the melting point of polypropylene is within this range, the second component described later thermally shrinks. When the melt flow rate is within the above range, the first component does not undergo heat shrinkage or, if it does, it undergoes little heat shrinkage, and the desired three-dimensional crimp is well expressed. is.

The first component preferably contains polypropylene in an amount of 50% by mass or more, more preferably 70% by mass or more. Alternatively, the first component may consist essentially of polypropylene without other thermoplastic resins. When the first component contains another thermoplastic resin, the other thermoplastic resin may be a polyolefin elastomer to be described later. Alternatively, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and copolymers thereof, polyamide resins such as nylon 6, nylon 66, and copolymers thereof, and polymethylpentene and polyethylene (high-density polyethylene , low density polyethylene, linear low density polyethylene), and the like.

The second component contains a propylene-alpha olefin copolymer. Here, the α-olefin is ethylene or an α-olefin having 4 to 20 carbon atoms (excluding propylene). The propylene-α-olefin copolymer may contain only one α-olefin, in which case it will be a binary copolymer. Alternatively, the number of α-olefins constituting the copolymer may be two or more, in which case the copolymer will be a ternary or higher olefin. In the propylene-α-olefin copolymer, the α-olefin content is preferably 1% by mass or more and 15% by mass or less, more preferably 1.2% by mass or more and 10% by mass or less, and 1.5% by mass or more7 % by mass or less is particularly preferable, and 1.5% by mass or more and 6.6% by mass or less is most preferable.

In the present embodiment, the second component is, as a propylene-α-olefin copolymer, a propylene/ethylene copolymer having an ethylene content of 1% by mass or more and 15% by mass or less (hereinafter simply referred to as "propylene/ethylene copolymer ) are preferably included. A propylene/ethylene copolymer having an ethylene content within this range tends to shrink when heat-treated at, for example, about 120° C. to about 140° C., and tends to favorably develop a desired three-dimensional crimp in a conjugate fiber. When the ethylene content is less than 1% by mass, the content of ethylene in the propylene-ethylene copolymer becomes small, so the properties of the propylene-ethylene copolymer are considered to be the same as those of a propylene homopolymer. Therefore, when the first component and the second component are compared, the difference in thermal shrinkage ratio tends to be small, and the thermal shrinkability of the conjugate fiber tends to be small. If the ethylene content exceeds 15% by mass, excessive steric crimping occurs, that is, the amount of heat shrinkage accompanying the development of steric crimping during heat treatment becomes very large, and the texture of the fiber assembly including the batting deteriorates. Otherwise, the density of the fibrous mass increases and the drapeability decreases. The ethylene content is more preferably 1.2% by mass or more and 10% by mass or less, particularly preferably 1.5% by mass or more and 6.5% by mass or less, and most preferably 1.5% by mass. It may be more than or equal to 5% by mass or less.
The propylene/ethylene copolymer may be either a random copolymer or a block copolymer. Random copolymers are preferred in consideration of heat shrinkability.

The propylene/ethylene copolymer may have, for example, a melting point of 130° C. to 148° C. or 135° C. to 145° C. before spinning. In addition, the melt flow rate (MFR; measurement temperature 230°C, load 21.18N (2.16 kgf)) before spinning is preferably 50 g/10 minutes or less, and 10 g/10 minutes or more and 30 g/10 minutes or less. is more preferable. When the melting point of the propylene/ethylene copolymer is within this range, the desired three-dimensional crimps are easily developed by heat treatment at about 100°C to 140°C. Further, when the melt flow rate is within this range, the spinnability during fiber production is good.

Alternatively, in the present embodiment, the second component is a propylene-α-olefin copolymer having a 1-butene content of 0.1% by mass or more and 3.5% by mass or less and an ethylene content of 1% by mass or more and 7% by mass. % or less of a propylene/1-butene/ethylene copolymer (hereinafter simply referred to as “propylene/1-butene/ethylene copolymer”). A propylene/1-butene/ethylene copolymer having a content of 1-butene and ethylene within the above range is also similar to the propylene/ethylene copolymer described above, for example, from about 120°C to about 140°C. It is easy to shrink by the heat treatment of , and it is easy to satisfactorily develop the desired three-dimensional crimp in the composite fiber.

If the 1-butene content is less than 0.1% by mass or the ethylene content is less than 1% by mass, the heat shrinkability tends to decrease. When the 1-butene content exceeds 3.5% by mass or the ethylene content exceeds 7% by mass, excessive steric crimping occurs. As a result, the texture of the fibrous aggregate including the filling may deteriorate, or the density of the fibrous aggregate may increase and the drapeability may deteriorate. The 1-butene content is more preferably 1% by mass or more and 3.2% by mass or less, particularly preferably 1.5% by mass or more and 3% by mass or less, and most preferably 1.8% by mass. It may be more than or equal to 2.8% by mass or less.
The ethylene content is more preferably 2% by mass or more and 4.5% by mass or less, particularly preferably 2.5% by mass or more and 4% by mass or less, and most preferably 2.8% by mass or more and 3 0.8% by mass or less. The propylene/1-butene/ethylene copolymer may be either a random copolymer or a block copolymer. Random copolymers are preferred in consideration of heat shrinkability.

The propylene/1-butene/ethylene copolymer may have, for example, a melting point in the range of 120°C to 145°C or in the range of 130°C to 140°C before spinning. In addition, the melt index (MI; measurement temperature 230°C, load 21.18 N (2.16 kgf)) before spinning is preferably 50 g/10 minutes or less, and 3 g/10 minutes or more and 30 g/10 minutes or less. is more preferable, and 5 g/10 minutes or more and 20 g/10 minutes or less is particularly preferable. When the melting point of the propylene/ethylene copolymer is within this range, the desired three-dimensional crimps are easily developed by heat treatment at about 100°C to 140°C. Further, when the melt index is within this range, the spinnability during fiber production is good.

The second component preferably contains 50% by mass or more, more preferably 70% by mass or more of the propylene-α-olefin copolymer. Alternatively, the second component may consist essentially of the propylene-α-olefin copolymer without other thermoplastic resins. When the second component contains another thermoplastic resin, the other thermoplastic resin may be a polyolefin-based elastomer described later, or may be referred to as "another thermoplastic resin" in relation to the first component. It may be one or more resins selected from the thermoplastic resins described.

The conjugate fiber of this embodiment contains a polyolefin elastomer in either one or both of the first component and the second component. By containing the polyolefin elastomer, it is possible to suppress the appearance of excessive steric crimps in the composite fiber, and the entire fiber has moderate elasticity, and when used as a batting, it does not lose bulk over time (settling). can be suppressed.

The polyolefin elastomer is preferably contained in an amount of 10% by mass or more and 30% by mass or less, more preferably 12% by mass or more and 25% by mass or less of the component containing it. If the proportion of the polyolefin-based elastomer is less than 10% by mass, the effect of containing the elastomer may be difficult to obtain, and if it exceeds 30% by mass, the spinnability during fiber production may deteriorate. When the polyolefin elastomer is contained in both the first and second components, the ratio of the polyolefin elastomer to the mass of the entire fiber is preferably 10% by mass or more and 30% by mass or less.

The polyolefin elastomer may be contained only in the second component. As described above, the second component contains a heat-shrinkable propylene-α-olefin copolymer, particularly a propylene/ethylene copolymer or a propylene/1-butene/ethylene copolymer. Containing an elastomer facilitates control of the heat shrinkability of the second component, and facilitates the design of the conjugate fiber to have a desired three-dimensional crimp.

As the polyolefin-based elastomer, one or more polyolefin resins selected from polyethylene, polypropylene, and copolymers of propylene and α-olefin having 4 or more carbon atoms, such as 4 to 8 carbon atoms, are used as hard segments, Examples include thermoplastic elastomers having α-olefin rubber or other rubbers as soft segments. The α-olefin rubber may be, for example, a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. Examples of α-olefins include propylene, 1-butene, 1-pentene, 3,3-dimethyl-1-butene, 4-methyl-1-pentene, 4,4-dimethyl-1-pentene, 1-decene, 1 -dodecene, 1-tetradecene, and 1-octadecene. More specifically, the α-olefin rubber may be, for example, ethylene-propylene rubber such as ethylene-propylene rubber, ethylene-butene rubber, and ethylene-propylene-diene rubber. Examples of other soft segment rubbers include diene rubbers such as isoprene rubber, butadiene rubber, butyl rubber, propylene-butadiene rubber, acrylonitrile-butadiene rubber, and acrylonitrile-isoprene rubber.

The melting point of the polyolefin elastomer is not particularly limited. When the olefinic elastomer is contained in the second component, its melting point is more preferably higher than the melting point of the propylene/α-olefin copolymer and 160°C or lower. When the melting point of the polyolefin-based elastomer is within the above range, the heat resistance is high and, for example, the volume is less likely to decrease due to the heat treatment during the production of the batting.

The melt flow rate (MFR; measurement temperature 230° C., load 21.18 N (2.16 kgf)) of the polyolefin elastomer is not particularly limited, and may be, for example, 1 g/10 min or more and 30 g/10 min, preferably 3 g. /10 min to 20 g/10 min, more preferably 5 g/10 min to 15 g/10 min. When the melt flow rate is within this range, the spinnability during fiber production is good.

In this embodiment, the polyolefin elastomer may contain propylene as a hard segment and be polymerized using a metallocene catalyst. In a polyolefin thermoplastic elastomer polymerized without using a metallocene catalyst, the crystalline structure and amorphous structure portions in the elastomer are dispersed with a size of 300 nm to 1 μm. An elastomer in which hard segments and soft segments of this size are dispersed has poor flexural elasticity of the elastomer itself, and flexural elasticity and bulk recovery of fibers and fiber aggregates containing the elastomer, and melt spinning becomes difficult. There is a tendency. On the other hand, in a polyolefin thermoplastic elastomer polymerized using a metallocene catalyst, the crystalline structure and amorphous structure portions in the elastomer are dispersed with a size of 5 to 50 nm. Composite fibers using this elastomer are highly heat resistant and tend to be excellent in bulk recovery and strain resistance after repeated deformation.

Examples of polyolefin-based elastomers that can be used in the present embodiment include “Milastomer (registered trademark)” and “Tafmer (registered trademark)” manufactured by Mitsui Chemicals, Inc., and “Esporex (registered trademark)” manufactured by Sumitomo Chemical Co., Ltd. , "Thermorun®" and "Xerus®" manufactured by Mitsubishi Chemical Corporation, and "WELNEX®" manufactured by Japan Polypropylene Corporation, but are not limited thereto.

The conjugate fiber of the present embodiment preferably has a cross-sectional structure in which the second component is exposed over a length of 20% or more of the length of the peripheral surface of the fiber. As such a cross-sectional structure, an eccentric core-sheath type cross-section in which the first component is a core component, the second component is a sheath component, and the center of gravity of the first component (core component) is shifted from the center of gravity of the fiber, and A side-by-side cross section (also referred to as “parallel cross section”) in which the first component and the second component are bonded together can be mentioned. According to such a cross-sectional structure, it is possible to obtain a conjugate fiber having excellent shrinkability and excellent crimp development.
When the heat-shrinkable conjugate fiber is an eccentric sheath-core conjugate fiber, the eccentricity of the first component is preferably in the range of 20 to 60%, more preferably in the range of 30 to 50%. preferable. The eccentricity here is defined by the following equation.

The fiber cross-sectional shape (peripheral shape) of the conjugate fiber of the present embodiment may be circular, or may be elliptical, Y-shaped, I-shaped, polygonal, or star-shaped. Also, the fiber cross section (peripheral shape) of the first component may be circular, or may be elliptical, Y-shaped, I-shaped, polygonal, or star-shaped.

The combined ratio of the first component to the second component may be in the range of 3:7 to 7:3 by volume, preferably in the range of 4:6 to 6:4. If the ratio of the second component is too small, the fibers may not shrink sufficiently and the desired three-dimensional crimp may not be developed. If the ratio of the second component is too large, the amount of heat shrinkage of the conjugate fiber becomes too large, so that the conjugate fiber excessively shrinks during the heat treatment, resulting in a fiber assembly having a high density and low drapeability. may become In addition, since the propylene-α-olefin copolymer, which is softer than polypropylene and has a low melting point, accounts for a large proportion of the entire fiber, the resulting fiber aggregate may have a low elasticity.

In this way, the composite fiber obtained by combining two specific components so as to have an eccentric core-sheath type cross section or a side-by-side type cross section is three-dimensionally crimped at the fiber stage or by subjecting it to heat treatment after manufacturing the fiber. will be expressed. Here, the term "steric crimp" is used to distinguish it from mechanical crimping, in which crests (or crests) of crimps are acute-angled as shown in FIG. In addition, "a three-dimensional crimp is expressed" means, for example, a crimp with curved crests (wavy crimp) as shown in FIG. In addition to crimps (helical crimps), crimps in which wavy crimps and helical crimps are mixed as shown in FIG. 1C, and mechanical crimps as shown in FIG. It refers to the development of crimps in which at least one of crimps and spiral crimps are mixed.

The conjugate fiber of the present embodiment may exhibit three-dimensional crimps at the fiber stage. Composite fibers that are three-dimensionally crimped at the fiber stage can provide a batting that is bulky even when used as it is without being subjected to a heat treatment, and that has little decrease in bulk over time. Alternatively, the conjugate fiber of the present embodiment may not exhibit steric crimping at the fiber stage, but may exhibit steric crimping upon heating. Alternatively, the conjugate fiber of the present embodiment expresses steric crimps in the fiber stage, but upon heating, it expresses further steric crimps, or the degree of steric crimps that have already developed becomes stronger. It can be something like A sheet-like batting obtained by producing a fibrous web by using conjugate fibers that exhibit or increase the degree of three-dimensional crimping by heating and subjecting this to heat treatment has stretchability. .

When the conjugate fiber of the present embodiment expresses three-dimensional crimps at the fiber stage, the number of crimps is 10/25 mm or more and 30/25 mm or less, particularly 12/25 mm or more and 25/25 mm or less. It's okay. When mechanical crimps, wavy crimps and/or helical crimps are mixedly present in a conjugate fiber, the mechanical crimps are also included in the number of three-dimensional crimps. When three-dimensional crimps are developed by heat treatment, the conjugate fiber of the present embodiment has a number of crimps after heat treatment of 15/25 mm or more and 90/25 mm or less, particularly 18/25 mm or more and 70/25 mm or less. you can The number of crimps is measured according to JIS L 1015. If many steric crimps are developed in the conjugated fibers, the initial bulk of the batting containing the conjugated fibers tends to be small.

The conjugate fiber of the present embodiment does not develop excessive three-dimensional crimps even when heated. For example,
1) Dry heat shrinkage measured at a temperature of 140°C for 15 minutes at an initial load of 0.45 mN/dtex (hereinafter referred to as “140°C dry heat shrinkage”),
2) With an initial load of 0.45 mN/dtex, the temperature is raised from room temperature (18°C) at a rate of 10°C per minute. The temperature when the sample length and thermal shrinkage rate are measured from the start of temperature rise, and the integrated heat shrinkage rate from the start of temperature rise exceeds 1% (hereinafter, "1% heat shrinkage start temperature"),
3) Dry heat shrinkage measured at a temperature of 120°C for 15 minutes and an initial load of 0.018 mN/dtex (hereinafter referred to as “120°C dry heat shrinkage”)
Appears in

The conjugate fiber of the present embodiment has a large 120° C. dry heat shrinkage rate and a small 140° C. dry heat shrinkage rate. In other words, the conjugate fiber of the present embodiment, which exhibits a large thermal shrinkage under a low load and a small thermal shrinkage under a high load, does not exhibit excessive three-dimensional crimps. Such conjugate fibers undergo large heat shrinkage when no load (tension) is applied or when a small load is applied, but when a certain amount of load is applied, for example, when a card web or fibers are entangled with each other, In a state such as a fiber sheet in which the fibers are fixed to each other to some extent, the amount of thermal shrinkage during heat treatment is suppressed, so moderate three-dimensional crimps are developed. Therefore, according to the conjugate fiber of the present embodiment, the initial bulk of the fiber assembly can be increased without causing poor formation and a rapid decrease in bulk, and the fiber assembly can be formed due to the three-dimensional crimp. It has resilience and cushioning properties to be used.

The conjugate fiber of this embodiment may have a 140° C. dry heat shrinkage of 10% or less. Since the 140° C. dry heat shrinkage rate is measured with a relatively large initial load, the value tends to be small for fibers that are less likely to develop three-dimensional crimps, that is, fibers that are less likely to undergo heat shrinkage. The 140° C. dry heat shrinkage of the conjugate fiber of the present embodiment may be 8% or less, 5% or less, 3% or less, or 0%. A dry heat shrinkage rate of 0% at 140° C. means that no heat shrinkage can be confirmed by the measurement method.

The conjugate fiber of the present embodiment may have a 1% heat shrinkage starting temperature of 100° C. or higher. Here, the 1% heat shrinkage starting temperature means that the fiber shrinks by 1% when the temperature is raised at a constant heating rate (10°C/min) with a load of 0.45 mN/dtex applied to the fiber. means temperature. The higher the 1% heat shrinkage start temperature, the harder the fiber to heat shrink when the load applied to the fiber is large (if the fibers are in a fiber aggregate, the fibers are strongly entangled or bonded). In a fiber having a composite form as in the embodiment, steric crimping is difficult to develop. The 1% heat shrinkage starting temperature of the conjugate fiber of the present embodiment may be 120° C. or higher, 130° C. or higher, or 135° C. or higher.

The conjugate fiber of the present embodiment has a 120° C. dry heat shrinkage rate of 20% to 70%, preferably 30% to 60%, more preferably 35% to 55%, and particularly preferably 38% to 50%. may have The 120° C. dry heat shrinkage of the conjugate fiber of the present embodiment is measured with a small initial load, so it is suitable for observing the degree of three-dimensional crimp developed by heating. If the 120° C. dry heat shrinkage ratio is within this range, the degree of steric crimping that develops upon heating does not become too large, regardless of whether steric crimping occurs at the fiber stage or not. Even when subjected to treatment, the initial bulk of the batting or fiber mass containing this fiber can be increased.

The fineness of the conjugate fiber is not particularly limited, and is appropriately selected according to the application. For example, when used for batting, the bicomponent fibers may have a fineness of 0.5 dtex to 30 dtex, preferably 0.8 dtex to 20 dtex, more preferably 1.1 dtex to 18 dtex. When the batting is composed of conjugate fibers having a fineness within the above range, it is easy to obtain a batting that is excellent in bulkiness and has less decrease in bulk over time.

The fiber length of the composite fiber is also not particularly limited. For example, when the batting is made of bicomponent fibers, the fiber length of the bicomponent fibers may be in the range of 24 mm to 90 mm, preferably in the range of 28 mm to 75 mm, more preferably in the range of 32 mm to 65 mm. In particular, when it is used as a type of batting that is filled in bedding, etc. by blowing, the fiber length of the composite fiber may be in the range of 20 mm to 120 mm. Alternatively, when fibers are entangled to form a ball-like material and the aggregate is used as batting, the fiber length of the composite fiber may be in the range of 15 mm to 72 mm, or in the range of 20 mm to 64 mm. may be in the range of 24 mm to 48 mm, or in the range of 28 mm to 42 mm. Alternatively, when fabricating a fiber web using a carding machine and fabricating a batting or non-woven fabric by bonding the fibers with a binder resin or the like as necessary, the fiber length may be in the range of 20 mm to 100 mm, It is preferably in the range of 28 mm to 72 mm, more preferably 32 mm to 64 mm.

The conjugate fiber of this embodiment can be produced, for example, as follows.
First, a polypropylene constituting the first component and a propylene-α-olefin copolymer and a polyolefin elastomer constituting the second component are prepared. Other thermoplastic resins constituting the first component and the second component are prepared as necessary.

Next, the first component is melt spun at a spinning temperature of 250° C. to 350° C. and the second component is melt spun at a spinning temperature of 200° C. to 300° C. using an appropriate composite nozzle so as to obtain the desired fiber cross-sectional structure. , withdraw at a take-up speed of 100 to 1500 m/min to obtain a spun filament. The fineness of the spun filament may be 3 dtex or more and 50 dtex or less.

Next, the stretching temperature is set to 50° C. or more and less than the melting point of the second component, and the stretching treatment is performed at a draw ratio of 1.8 times or more. When the second component contains a plurality of resins, the temperature of the resin with the lowest melting point is defined as the melting point of the second component. A more preferable lower limit of the stretching temperature is 60°C or higher. A more preferable upper limit of the stretching temperature is 10°C lower than the melting point of the second component. If the stretching temperature is lower than 50° C., the crystallization of the second component is difficult to proceed, so there is a tendency that the heat shrinkage increases and the bulk recoverability tends to decrease. If the drawing temperature is higher than the melting point of the second component, the fibers tend to fuse together. A more preferable lower limit of the draw ratio is 2 times. A more preferable upper limit of the draw ratio is 4.5 times. When the draw ratio is 1.8 times or more, the draw ratio is not too low, and it becomes easy to obtain a fiber having the above-described wavy crimp and/or spiral crimp, and the initial bulk and rigidity of the fiber itself are improved. does not become smaller.

The drawing method is not particularly limited, and a wet drawing in which drawing is performed while heating with a high temperature liquid such as hot water (50 ° C. or more and less than 100 ° C.), a dry drawing in which drawing is performed while heating in a high temperature gas or with a high temperature metal roll. A known drawing method such as drawing or steam drawing, in which the fiber is drawn while heating the fiber under normal pressure or pressurized steam at 100° C. or higher, may be used. Among these, wet drawing using hot water is preferable because it is productive, economical, and can heat the entire undrawn fiber bundle easily and uniformly.

A predetermined amount of a fiber treatment agent is applied to the obtained drawn filaments as necessary, and mechanical crimps are given by a crimper (crimping device). The number of crimps applied by the crimper may be, for example, 8/25 mm to 30/25 mm, preferably 10/25 mm to 30/25 mm, more preferably 12/25 mm to 25/25 mm. be.

Before and after the stretching treatment, for example, after imparting mechanical crimping, annealing treatment is performed in an atmosphere such as dry heat, wet heat, or steam heat at 50 ° C. to 120 ° C., preferably 60 ° C. to 100 ° C. as necessary. may When the temperature during the annealing treatment is increased, the fibers can be made to develop three-dimensional crimps, and fibers having three-dimensional crimps can be obtained at the fiber stage. The annealing treatment may also serve as a drying treatment for the fiber treatment agent when it is carried out after mechanical crimping. After that, the fibers are cut into predetermined fiber lengths.

(batting)
The conjugate fiber of the present embodiment can be used as batting for clothing, bedding, stuffed toys, cushioning materials, heat insulating materials, and the like. The batting may contain, for example, 10% by mass or more of the composite fiber of the present embodiment.

The form of the filling is not particularly limited. For example, after the fiber is manufactured, raw cotton mixed with other fibers as necessary may be subjected to fiber opening treatment, then blown with pressurized gas, and then filled into the product as it is, or filled into a bag. you can The filling filled in a bag-like object is used by attaching the bag-like object to clothing or the like. When the spread fiber is used as the batting as it is, the conjugate fiber of the present embodiment may express three-dimensional crimps at the fiber stage, and in that case, the initial bulk is larger and the decrease in bulk over time is less. You can get batting. Alternatively, when the conjugate fiber of the present embodiment does not develop a three-dimensional crimp at the fiber stage, it may be subjected to a heat treatment to develop a three-dimensional crimp before filling. Alternatively, even if the conjugate fiber of the present embodiment is filled into a product or the like as a batting without developing three-dimensional crimps, the fiber has elasticity due to the inclusion of the polyolefin-based elastomer. less bulk loss.

The batting may also be in the form of a pile of intertwined fibers. The batting of this form can be produced by using a processing machine that processes the spread raw cotton into fluff. In the case of manufacturing the batting of a pill-like material, the conjugate fiber of the present embodiment may exhibit three-dimensional crimps at the fiber stage, in which case a batting having a larger initial bulk and a less decrease in bulk over time is produced. Obtainable. Alternatively, when the conjugate fiber of the present embodiment does not develop a three-dimensional crimp at the fiber stage, it may be subjected to a heat treatment to develop a three-dimensional crimp before being processed into a pill. Alternatively, even if the conjugate fiber of the present embodiment is processed into a pill-like material without developing steric crimps, the fiber has elasticity due to the inclusion of the polyolefin-based elastomer, so the resulting batting can be maintained over time. Less bulk loss results.

Alternatively, the batting may be in sheet form. For example, after the conjugate fiber of the present embodiment is mixed with other fibers as necessary, a fiber web is produced by a carding machine or the like to form a sheet-like material, and this sheet-like material may be used as the batting as it is. The sheet-like batting may be a laminate comprising a plurality of sheets. In the sheet-like batting, when the conjugate fiber of the present embodiment expresses three-dimensional crimps, the batting has a larger initial bulk and less volume reduction over time. Alternatively, even if the conjugate fiber of the present embodiment constitutes a sheet-like batting without developing three-dimensional crimps, since the fiber has elasticity due to the inclusion of the polyolefin elastomer, the obtained batting will not deteriorate over time. Less bulk loss results.

In the sheet-like batting, the fibers may be bonded together. The bonding may be by a thermoadhesive fiber different from the conjugate fiber of the present embodiment (a fiber that exhibits adhesiveness by melting or softening some or all of its components when heated), Alternatively, it may be based on a binder resin (resin bond), or may be based on one component of the composite fiber of the present embodiment.

The thermoadhesive fiber preferably has a bonding component that has a melting point lower than that of the components constituting the conjugate fiber of the present embodiment. The thermally bondable fibers can be single or composite fibers, for example, polyethylene (including high density polyethylene, low density polyethylene, and linear low density polyethylene) occupying at least a portion of the fiber surface. Binder resins may optionally be those used in the manufacture of batting, such as acrylics and polyurethanes. When the batting is formed by bonding fibers together, it is preferable to bond the fibers with a thermoadhesive fiber or a binder resin. This is because these means allow the fibers to be bonded to each other by heat treatment at a relatively low temperature (for example, 120° C. to 150° C.).

Adhesion treatment by the thermoadhesive fiber or binder resin or one component of the composite fiber of the present embodiment is usually thermal adhesion treatment, but may be other adhesion treatments such as electron beam irradiation or ultrasonic treatment. . During the heat bonding treatment, the conjugate fiber of the present embodiment is exposed to heat to develop three-dimensional crimps. Therefore, the resulting batting has shape retention properties due to thermal bonding between fibers, and has stretchability due to the developed three-dimensional crimps. Such a batting is suitable, for example, as a batting for a batted jacket using a knitted fabric as a base fabric, and can expand and contract along with the expansion and contraction of the knitted fabric. As will be described later, when the sheet-like batting is produced by a method in which a fibrous web is prepared and then heat-treated, when the heat treatment is not accompanied by thermal bonding, the degree of freedom of the fibers is large, and a more flexible batting can be obtained. be done.

The sheet-like batting is produced by producing a fibrous web containing 10% by mass or more of the conjugate fiber of the present embodiment, and subjecting the fibrous web to heat treatment to develop and/or already develop three-dimensional crimps in the conjugate fiber. It may be manufactured by a manufacturing method including increasing the degree of steric crimping. The heat treatment may involve thermal bonding. Alternatively, the heat treatment may be performed only for the purpose of developing steric crimps in the conjugated fibers and/or increasing the degree of steric crimps developed in the conjugated fibers without thermal bonding.

Bonding between fibers may be a thermal bonding process in which a fiber web to which a binder resin is attached is heated. The binder resin may be applied to the fibrous web, for example by spraying. The loading may be, for example, 5% to 100% by weight of the fibrous web.

When heat-bondable fibers are blended to form a fibrous web, the bonding treatment may be a heat treatment, which may be carried out to soften or melt the heat-bondable fibers. When heat-adhesive fibers are mixed, the proportion of heat-adhesive fibers in the fibrous web may be, for example, 10% to 90% by weight.

The basis weight of the sheet-like filling is not particularly limited, and is appropriately selected according to the application. For example, when a sheet-like batting is used as the batting for the jacket, it may have a basis weight of 15 g/m ² to 150 g/m ² , preferably 20 g/m ² to 120 g/m ² . Also, the sheet-like filling has a specific volume of, for example, 30 cm ³ /g to 5000 cm ³ /g, preferably 50 cm ³ /g to 2500 cm ³ /g. The specific volume is an index of the bulkiness of the filling, and if it is too small, the filling may be too bulky to provide the functions required for the filling, such as sufficient warmth and cushioning properties.

According to the conjugate fiber of the present embodiment, it is easy to obtain a sheet-like batting having the aforementioned specific volume. This is because the conjugate fiber of the present embodiment does not excessively develop three-dimensional crimps even when subjected to a heat treatment, so that an increase in fiber density due to the development of fine three-dimensional crimps is suppressed.

In any form, the batting containing the conjugate fiber of the present embodiment preferably contains the conjugate fiber of the present embodiment in an amount of 10% by mass or more, preferably 20% by mass or more, and more preferably 30% by mass or more. Alternatively, the batting may consist only of the composite fiber of the present embodiment.

When the batting contains other fibers, the other fibers are, for example, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and copolymers thereof, nylon 6, nylon 66, and copolymers thereof. Synthesis consisting of one or more thermoplastic resins selected from polyamide resins, polyolefin resins such as polymethylpentene and polyethylene (including high density polyethylene, low density polyethylene, linear low density polyethylene), and acrylic resins. It may be a fiber. Synthetic fibers may be either single fibers or composite fibers. As described above, in the sheet-like batting, when the fibers are bonded with the heat-adhesive fibers, the heat-adhesive fibers are used as the other fibers.
Alternatively, other fibers may be natural fibers such as cotton, silk, wool, hemp, and pulp, regenerated fibers such as rayon, cupra, and solvent spun cellulose fibers. Alternatively, the composite fiber of this embodiment may be used together with down (down, feather).

The filling containing the composite fiber of the present embodiment is used for clothing such as jackets and vests and other winter clothing, beds, mattresses, comforters, bed mats, mattresses, pillows and other bedding, plush toys, and cushioning materials (for example, for automobiles, Cushioning material for aircraft, railroad vehicle, and ship seats, as well as cushioning material for general household and office seating, clothing pads (e.g., women's brassiere pads, shoulder pads, elbow pads, knee pads, etc.);

(Fiber assembly)
The conjugate fiber of the present embodiment may be applied to uses other than batting. In that case, the conjugate fiber of the present embodiment may be used in the form of a fiber assembly containing 10% by mass or more of this. When fibers other than the composite fiber of the present embodiment are included, examples of the other fibers are as described above in relation to the batting.

The fiber assemblage can be, for example, a woven, knitted or non-woven fabric, in particular a non-woven fabric. The nonwoven fabric may be, for example, a thermally bonded nonwoven fabric in which fibers are thermally bonded with a thermally adhesive fiber or a binder, or an entangled nonwoven fabric in which fibers are entangled with each other. A nonwoven fabric comprising the conjugate fibers of the present embodiment is loftier and loses less loft over time. Furthermore, the nonwoven fabric containing the conjugated fibers of the present embodiment can exhibit stretchability due to the three-dimensional crimp developed in the conjugated fibers. In particular, after the fiber web is produced, it is subjected to entangling treatment (for example, needle punching treatment or high-pressure fluid flow treatment) as necessary, and then to heat treatment to develop and/or already develop steric crimps in the conjugate fibers. A nonwoven fabric produced by a method of increasing the degree of three-dimensional crimping exhibits higher stretchability.

The fiber assembly containing the conjugate fiber of the present embodiment includes, for example, sanitary articles such as masks, supporters and bandages; absorbent articles such as disposable diapers, sanitary napkins, and panty sheets; and liquids such as cosmetics. Liquid-impregnated skin covering sheets (e.g., face masks, keratin care sheets, decollete sheets, etc.); wipers; wet tissues; cushioning materials; sheet).

The following were prepared as thermoplastic resins constituting the conjugate fibers.
(polypropylene resin)
PP-A: manufactured by Prime Polymer Co., Ltd., trade name S105HG, melting point 160° C., MFR 30 g/10 min, Q value 4.7
PP-B: manufactured by Japan Polypropylene Corporation, trade name SA03, melting point 160° C., MFR 30 g/10 minutes, Q value 2.8
PP-C: manufactured by Japan Polypropylene Corporation, trade name SA03E, melting point 160° C., MFR 20 g/10 min, Q value 5.0

(Propylene-α olefin copolymer)
EP: manufactured by Prime Polymer Co., Ltd., trade name Y2045GP, melting point 140° C., MI 30 g/10 min, propylene/ethylene copolymer with an ethylene content of 4.78% by mass EPB: manufactured by Japan Polypropylene Co., Ltd., trade name FW4B, Propylene/1-butene/ethylene copolymer having a melting point of 138°C, an MI of 7 g/10 min, a 1-butene content of 2.3 mass%, and an ethylene content of 3.3 mass%

(polyolefin elastomer)
PPR-A: manufactured by Japan Polypropylene Corporation, trade name WELNEX, melting point 150° C., MI 30 g/10 min, polypropylene elastomer in which rubber component is nano-dispersed PPR-B: manufactured by Mitsui Chemicals, trade name Toughmer BL20300, melting point 150 ℃, MI30g/10min, Polypropylene elastomer with nano-dispersed rubber component

(Examples 1 to 7, Comparative Examples 1 to 3)
From the above thermoplastic resins, resins shown in Tables 1 and 2 were selected as constituents of the first component and the second component, respectively. Using the first component as the core component and the second component as the sheath component, using an eccentric core-sheath type composite nozzle, setting the composite ratio (volume ratio) of the first component/second component to 5/5, both the sheath component and the core component Melt extrusion was carried out at a spinning temperature of 270° C., and a take-up speed of 280 m/min.

The spun filament was drawn 3.5 times in hot water at 70° C. to obtain a drawn filament with a fineness of 6.7 dtex. Then, after applying a fiber treatment agent, the drawn filaments were mechanically crimped at 16 crimps/25 mm using a stuffing box type crimper. Then, the filament was simultaneously annealed and dried for 15 minutes in a hot-air through-type heat treatment machine set at 70° C., and the filament was cut to a fiber length of 38 mm to obtain a conjugate fiber. All of the obtained composite fibers exhibited three-dimensional crimps at the fiber stage.

Regarding the obtained fiber, the Q value (after spinning) of polypropylene constituting the first component was measured according to the following method.
(Q value of polypropylene after spinning)
A single fiber obtained by spinning and drawing the first component under the same conditions as those employed in Examples was used as a sample, and a molecular weight distribution curve was obtained using a high-temperature GPC apparatus (manufactured by Polymer Laboratories, PL-220). rice field. The number average molecular weight Mn and weight average molecular weight Mw were determined from the molecular weight distribution curve, and the Q value was determined. Measurement conditions, etc. are as follows.
Detector: Differential refractive index detector RI
Column: Shodex HG-G (1 piece), HT-806M (2 pieces) (manufactured by Showa Denko)
Solvent: 1,2,4-trichlorobenzene (TCB) (0.1% BHT added)
Flow rate: 1.0 mL/min, column temperature: 145°C
Sample preparation: Add 5 mL of solvent to 5 mg of sample, stir at about 160°C to 170°C for 30 minutes, and then filter using a metal filter Injection volume: 0.200 mL
Standard sample: Monodisperse polystyrene (manufactured by Tosoh)
Data processing: GPC data processing system (manufactured by TRC)

For the obtained fibers, in order to evaluate changes in bulk over time, box test settling described below was measured.
(box test failure)
30 g of short fibers opened using a parallel card are prepared. This spread cotton is packed in an acrylic cylindrical box (diameter of cylindrical box: about 200 mm), and the initial thickness is measured with a metal straightedge. An acrylic lid (diameter: about 200 mm) and a weight are placed on the filled fibers, and the short fibers in the box are left for 30 minutes while a load of 450 gf is applied. After 30 minutes have passed, remove the weight and the acrylic cover, measure the thickness of the spread cotton 30 minutes after removing the weight with a metal straightedge, and measure the reduction ratio of the thickness to the initial thickness. rate) is calculated by the following formula.
Settling rate (%) = [(Initial thickness (mm) - Thickness after 30 minutes unloading (mm)) / Initial thickness (mm)] x 100

Also, the heat shrinkage properties of the obtained fibers were evaluated by the method described below.
(140°C dry heat shrinkage)
Measured according to JIS L 1015. An initial load of 0.45 mN/dtex (50 mg/de) was applied, and dry heat treatment was performed at a temperature of 140° C. for 15 minutes to measure shrinkage. The 140°C dry heat shrinkage was calculated according to the following formula.
140° C. dry heat shrinkage (%)=[(length of sample before dry heat treatment−length of sample after dry heat treatment)/(length of sample before dry heat treatment)]×100

(1% heat shrink start temperature)
Measured according to JIS L 1015 in the same manner as the 140°C dry heat shrinkage rate. The initial load is set to 0.45 mN/dtex (50 mg/de), and the length (initial length) of the sample is measured with the initial load applied. Then, the temperature is increased from room temperature (18° C.) at a rate of temperature increase of 10° C. per minute. The sample length and thermal shrinkage rate are measured at each temperature from the start of heating. The temperature is continued until the heat shrinkage rate integrated from the start of temperature rise exceeds 1%, and the temperature at which the heat shrinkage rate integrated from the start of temperature rise exceeds 1% is defined as the 1% heat shrinkage start temperature.

(120°C dry heat shrinkage)
According to JIS L1015, the grip interval was 100 mm, the treatment temperature was 120° C., the treatment time was 15 minutes, and the dry heat shrinkage was measured under an initial load of 0.018 mN/dtex. The 120°C dry heat shrinkage rate was calculated according to the following formula.
120° C. dry heat shrinkage (%)=[(length of sample before dry heat treatment−length of sample after dry heat treatment)/(length of sample before dry heat treatment)]×100

(Thickness of fiber web before thermal processing, thickness of fiber web after thermal processing)
Each fiber of Examples 1 to 7 and Comparative Examples 1 to 3 and a polypropylene single fiber (fineness: 6.7 dtex, fiber length: 51 mm) were mixed with a polypropylene single fiber ratio of 70% by mass (Examples, Comparative 30% by mass of the conjugated fiber of the example), and after blending, the fibers are opened using a parallel carding machine to obtain a fiber web with a basis weight of 80 g/m ² , and the thickness of this web is measured without load. was measured with a metal straightedge. This fibrous web was subjected to heat treatment for 120 seconds in a hot air through-type heat treatment machine set at 120°C. The thickness of the fibrous web after heat treatment is measured with a metal straight edge without load. Each of the fiber webs after the heat treatment had a basis weight of 100 g/m ² .

Tables 1 and 2 show box test settling and heat shrinkage properties of the conjugate fibers of each example and each comparative example.

All of the conjugate fibers of Examples 1 to 7 had a low settling rate in the box test and little decrease in bulk over time. Moreover, all of the fibers of Examples 1 to 5, in which the second component is a propylene/ethylene copolymer, had a 140°C dry heat shrinkage rate of 0% and a 1% heat shrinkage starting temperature of 140°C or higher. . The fibers of Examples 6 and 7, in which the second component is a propylene/1-butene/ethylene copolymer, have dry heat shrinkage at 140°C of 3.0% and 5.0%, respectively, and 1% heat shrinkage starts. The temperatures were 137°C and 134°C, respectively. As is clear from these facts, the conjugate fibers of Examples 1 to 7 have lower heat shrinkability than the fibers of the comparative examples, and when the fibers are produced and then subjected to heat treatment, fine three-dimensional windings are obtained. Shrinkage was difficult to occur. This is also evidenced by the higher web thickness after heat processing and also the lower 120° C. dry heat shrinkage, particularly for the fibers of Examples 1-5. That is, the conjugate fibers of Examples 1 to 7 were capable of providing batting that exhibited a relatively large initial bulk even after thermal processing.

Since the fiber of Comparative Example 1 did not contain a polyolefin elastomer, the box test set was large, the heat shrinkability was large, and many fine three-dimensional crimps were developed by heating. Therefore, the web thickness after thermal processing using the fibers of Comparative Example 1 was the smallest among the Examples and Comparative Examples. Since the fiber of Comparative Example 2 contained a small proportion of the polyolefin-based elastomer in the second component, the settling in the box test was slightly large, the heat shrinkability was large, and many fine three-dimensional crimps were developed by heating. and the web thickness was small after thermal processing. In the fiber of Comparative Example 3, since the Q value of the polypropylene as the first component was small, the heat shrinkability was large, fine three-dimensional crimps were likely to be developed by heating, and the web thickness after heat processing was small.

The present invention includes the following aspects.
(Aspect 1)
A first component containing polypropylene having a Q value (ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn)) of 3.5 or more and 6.5 or less, and a propylene-α-olefin copolymer and a second component comprising
either one or both of the first component and the second component comprise a polyolefin elastomer;
The first component is a core component, the second component is a sheath component, and an eccentric core-sheath type fiber cross section in which the center of gravity of the first component is deviated from the center of gravity of the fiber, or the first component and the above Having a side-by-side fiber cross section in which the second component is bonded,
In the component containing the polyolefin elastomer, the proportion of the polyolefin elastomer is 10% by mass or more and 30% by mass or less.
Composite fiber.
(Aspect 2)
The composite fiber according to aspect 1, wherein the polyolefin elastomer is contained only in the second component.
(Aspect 3)
The conjugate fiber of aspect 1 or 2, wherein said polyolefin-based elastomer is a polyolefin-based elastomer comprising propylene and a metallocene catalyst.
(Aspect 4)
The composite fiber according to any one of aspects 1 to 3, wherein the propylene-α-olefin copolymer is a propylene/ethylene copolymer having an ethylene content of 1% by mass or more and 15% by mass or less.
(Aspect 5)
The propylene-1-butene copolymer has a 1-butene content of 0.1% by mass or more and 3.5% by mass or less and an ethylene content of 1% by mass or more and 7% by mass or less. • The conjugate fiber of any one of aspects 1-3, which is an ethylene copolymer.
(Aspect 6)
The conjugate fiber of any one of aspects 1-5, having steric crimps.
(Aspect 7)
The dry heat shrinkage rate measured at a temperature of 140°C for 15 minutes and an initial load of 0.45 mN/dtex is 10% or less, and is measured at a temperature of 120°C for 15 minutes and an initial load of 0.018 mN/dtex. The conjugate fiber according to any one of aspects 1 to 6, which has a dry heat shrinkage rate of 20% or more and 70% or less.
(Aspect 8)
A fiber assembly comprising 10% by mass or more of the composite fiber according to any one of aspects 1 to 7.
(Aspect 9)
A batting comprising 10% by mass or more of the composite fiber according to any one of aspects 1 to 7.
(Mode 10)
The batting of aspect 9, wherein the fibers are bonded together.
(Aspect 11)
The batting according to aspect 9, which is a ball-like mass of intertwined fibers.
(Aspect 12)
Producing a fibrous web containing 10% by mass or more of the conjugate fiber of any one of aspects 1 to 7,
A method for producing batting, comprising subjecting the fibrous web to heat treatment to develop three-dimensional crimps in the composite fibers and/or to increase the degree of three-dimensional crimps that have already developed.
(Aspect 13)
13. The method of producing batting according to aspect 12, further comprising attaching a binder resin to the fibrous web, wherein the heat treatment is a thermal bonding treatment for heating the fibrous web to which the binder resin has been attached.

Since the conjugate fiber of the present invention develops moderate three-dimensional crimps at the fiber stage and/or after heat treatment, by using it, a batting with a higher initial bulk and a smaller decrease in bulk over time can be obtained. be able to.

Claims (18)

A first component containing polypropylene having a Q value (ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn)) of 3.5 or more and 6.5 or less, and a propylene-α-olefin copolymer and a second component comprising
The second component contains a polyolefin elastomer,
The first component is a core component, the second component is a sheath component, and an eccentric core-sheath type fiber cross section in which the center of gravity of the first component is deviated from the center of gravity of the fiber, or the first component and the above Having a side-by-side fiber cross section in which the second component is bonded,
In the second component, the proportion of the polyolefin elastomer is 10% by mass or more and 30% by mass or less,
The fiber length is 24 mm to 90 mm,
Composite fiber. The composite fiber according to claim 1, wherein the polyolefin elastomer is contained only in the second component. The composite fiber according to claim 1 or 2, wherein the polyolefin elastomer is a polyolefin elastomer containing propylene and a metallocene catalyst. The conjugate fiber according to any one of claims 1 to 3, wherein the propylene-α-olefin copolymer is a propylene/ethylene copolymer having an ethylene content of 1% by mass or more and 15% by mass or less. The propylene-1-butene copolymer has a 1-butene content of 0.1% by mass or more and 3.5% by mass or less and an ethylene content of 1% by mass or more and 7% by mass or less. - The composite fiber according to any one of claims 1 to 3, which is an ethylene copolymer. The conjugate fiber according to any one of claims 1 to 5, which has three-dimensional crimps. The conjugate fiber according to any one of claims 1 to 6 , which has a dry heat shrinkage of 10% or less measured at a temperature of 140°C for 15 minutes and an initial load of 0.45 mN/dtex. The conjugate fiber according to any one of claims 1 to 7, which has a dry heat shrinkage of 20% or more and 70% or less measured under conditions of a temperature of 120°C, a time of 15 minutes, and an initial load of 0.018 mN/dtex. A first component containing polypropylene having a Q value (ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn)) of 3.5 or more and 6.5 or less, and a propylene-α-olefin copolymer and a second component comprising
The second component contains a polyolefin elastomer,
The first component is a core component, the second component is a sheath component, and an eccentric core-sheath type fiber cross section in which the center of gravity of the first component is deviated from the center of gravity of the fiber, or the first component and the above Having a side-by-side fiber cross section in which the second component is bonded,
In the second component, the proportion of the polyolefin elastomer is 10% by mass or more and 30% by mass or less,
The fiber length is 20 mm to 120 mm,
Composite fiber for batting that is blown and filled. A first component containing polypropylene having a Q value (ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn)) of 3.5 or more and 6.5 or less, and a propylene-α-olefin copolymer and a second component comprising
The second component contains a polyolefin elastomer,
The first component is a core component, the second component is a sheath component, and an eccentric core-sheath type fiber cross section in which the center of gravity of the first component is deviated from the center of gravity of the fiber, or the first component and the above Having a side-by-side fiber cross section in which the second component is bonded,
In the second component, the proportion of the polyolefin elastomer is 10% by mass or more and 30% by mass or less,
The fiber length is 15 mm to 72 mm,
Composite fiber for pilling batting. A first component containing polypropylene having a Q value (ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn)) of 3.5 or more and 6.5 or less, and a propylene-α-olefin copolymer and a second component comprising
The second component contains a polyolefin elastomer,
The first component is a core component, the second component is a sheath component, and an eccentric core-sheath type fiber cross section in which the center of gravity of the first component is deviated from the center of gravity of the fiber, or the first component and the above Having a side-by-side fiber cross section in which the second component is bonded,
In the second component, the proportion of the polyolefin elastomer is 10% by mass or more and 30% by mass or less,
The fiber length is 20 mm to 100 mm,
Composite fiber for sheet-like batting. A method for producing a composite fiber comprising a first component and a second component, comprising:
A first component containing a polypropylene having a Q value (ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn)) of 3.5 or more and 6.5 or less;
A second component containing a propylene-αolefin copolymer and a polyolefin elastomer, wherein the proportion of the polyolefin elastomer is 10% by mass or more and 30% by mass or less when the entire second component is 100% by mass. death,
The first component is the core component, the second component is the sheath component, and the eccentric core-sheath type cross section in which the center of gravity of the first component (core component) is deviated from the center of gravity of the fiber, or the first component and the second component Obtaining a spun filament by melt spinning using a composite nozzle having a side-by-side cross section in which the
drawing the spun filament at a temperature of 50° C. or more and less than the melting point of the second component at a draw ratio of 1.8 or more;
cutting the drawn filament to a predetermined fiber length;
A method for producing a composite fiber comprising: A fiber assembly comprising 10% by mass or more of the composite fiber according to any one of claims 1 to 8 . A batting comprising 10% by mass or more of the composite fiber according to any one of claims 1 to 11 . 15. The batting of Claim 14 , wherein the fibers are bonded together. 10% by mass or more of the composite fiber according to any one of claims 1 to 8 and claim 10 ,
A batting that is a collection of pill-like substances made by intertwining fibers. Producing a fiber web containing 10% by mass or more of the composite fiber according to any one of claims 1 to 8 and claim 11 ,
A method for producing a sheet-like batting, comprising subjecting the fiber web to heat treatment to develop three-dimensional crimps in the composite fibers and/or to increase the degree of three-dimensional crimps that have already developed. 18. The method for producing a sheet-like batting according to claim 17 , further comprising attaching a binder resin to the fibrous web, and wherein the heat treatment is a heat bonding treatment for heating the fibrous web to which the binder resin has been attached.

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