JP6788367B2 - Composite fiber and batting - Google Patents

Description

The present invention relates to composite fibers and fiber aggregates using the composite fibers, particularly batting.

Various batting materials made of synthetic fibers have been proposed for clothing, bedding, stuffed animals, cushioning materials, heat insulating materials, and the like. For example, Patent Document 1 proposes a batting material composed of two types of latent crimp polyester composite fibers. Further, Patent Document 2 proposes a batting containing hollow polyester short fibers and cellulosic short fibers.

Japanese Unexamined Patent Publication No. 6-280148 JP-A-2007-125153 Japanese Unexamined Patent Publication No. 2-191720

Batting with synthetic fibers is more convenient than batting with natural fibers such as cotton and wool in terms of lightness and handleability, and batting with feathers in terms of animal protection, handleability and cost. More convenient than. Therefore, synthetic fiber batting is expected to be used in more products in the future, and synthetic fiber batting with performance closer to that of natural fibers and feathers (especially heat retention and bulkiness). Is always sought after.
The present invention focuses on the bulkiness of a synthetic fiber batting, and provides a synthetic fiber capable of forming a batting having a large initial bulk and maintaining the bulkiness for a longer period of time (that is, less likely to cause settling). The purpose is to do.

The first embodiment of the present invention includes polypropylene having a Q value (ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn)) of 3.5 or more and 6.5 or less. It consists of a component and a second component containing a propylene-α-olefin copolymer.
One or both of the first component and the second component contains a polyolefin-based elastomer.
An eccentric core sheath type fiber 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 is deviated from the center of gravity of the fiber, or the first component and the above. It has a side-by-side type fiber cross section to which the second component is bonded,
In the component containing the polyolefin-based elastomer, the proportion of the polyolefin-based elastomer is 10% by mass or more and 30% by mass or less.
Provides composite fibers. This composite fiber is suitable for forming batting.

Although the composite fiber has a fiber cross-sectional structure in which three-dimensional crimping is likely to occur, polypropylene satisfying 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 butylene content with a polyolefin-based elastomer, steric crimping does not occur excessively. In addition, this composite fiber has moderate elasticity and exhibits high resilience to deformation. Therefore, this composite fiber can provide a batting that is bulky and less likely to lose bulk over time.

1A to 1C are schematic views showing a form of three-dimensional crimp that can be expressed in the composite fiber of the present embodiment. FIG. 2 is a schematic view showing a form of three-dimensional crimp that can be expressed in the composite fiber of the present embodiment. FIG. 3 is a schematic view showing a form of mechanical crimping.

(Background to the present invention)
The present inventors used a polyolefin-based thermoplastic resin to use a latent crimpable composite fiber as described in Patent Document 1 in order to obtain a batting in which the bulk does not easily decrease with time (that is, it does not easily settle). Considered to configure. Polyolefin-based thermoplastic resins, especially polypropylene, 1) have excellent heat retention and heat insulating properties due to the low thermal conductivity of the resin itself, and 2) the density of the resin itself is low, and fibers of the same mass. It is suitable for batting because it is considered that a fiber aggregate having a larger bulk and / or a larger number of constituent fibers can be obtained when compared with the aggregate. Specifically, a latent crimpable composite fiber formed by composite 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 heat-bonding the fibers with a binder resin, the fiber shrinks due to the heat at the time of heat bonding, and a large number of fine three-dimensional windings are wound on the fiber. Shrinkage develops, the voids between the fibers become smaller, and the initial bulk of the batting becomes smaller. That is, when trying to obtain a batting of a predetermined thickness by using the composite fiber described in Patent Document 3, it is necessary to use more fibers, which increases the weight of the entire batting, resulting in a feeling of lightness and drape. The sex is reduced. On the other hand, in the batting using a single fiber composed only of polypropylene, since the polypropylene single fiber hardly expresses three-dimensional crimping, not only the initial bulk is small but also the bulk recovery property is low.

Therefore, the present inventors have stated that even if three-dimensional crimps occur, if the degree is not increased, a batting having a large initial bulk and excellent cushioning and bulk recovery during use can be obtained. Thought. Then, a specific polypropylene is used as the first component, a propylene / ethylene copolymer is used as the second component, and a polyolefin-based elastomer is further added to the first component and / or the second component to make the fiber cross section three-dimensional. When the composite fiber was prepared with a structure in which crimping was likely to occur, it was found that a batting having a large initial bulk and less likely to decrease in bulk over time could be obtained.
Hereinafter, the composite fiber of the present embodiment and the batting using the same will be described.

(Composite fiber)
The composite fiber of the present embodiment contains the first component containing polypropylene having a Q value (ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn)) of 3.5 or more and 6.5 or less. Consists of 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 one or both of the first component and the second component is a polyolefin-based elastomer. An eccentric core sheath type fiber cross section containing, the first component is a core component, the second component is a sheath component, and the center of gravity of the first component is deviated from the center of gravity of the fiber, or the first component and the second component. Is a composite fiber having a side-by-side type fiber cross section to which is bonded.

In the present embodiment, the first component contains polypropylene having a Q value of 3.5 or more and 6.5 or less. By using polypropylene having a Q value within this range, it is possible to obtain a composite fiber in which three-dimensional crimping is unlikely to occur excessively. When the Q value is less than 3.5, the degree of steric crimp becomes strong, and when the Q value exceeds 6.5, steric crimp is less likely to occur.

The range described here is for the Q value after spinning, but it is preferable that the Q value before spinning is also within the range described here. The Q value before spinning is generally provided by the resin manufacturer. The Q value of polypropylene after spinning is measured for polypropylene contained in the first component of the composite fiber. When it is difficult to measure the Q value of polypropylene constituting the composite fiber, only polypropylene is spun under the same conditions as the spinning conditions of the composite fiber (spinning temperature is the first component). The Q value of the single fiber thus obtained may be measured, and the measured value may be used as the Q value of polypropylene contained in the first component of the present embodiment.

As long as the Q value of polypropylene satisfies the above range, for example, the melting point 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 less. The melting point can be obtained from the heat of fusion curve obtained by DSC, and the temperature showing the peak (melting peak temperature) is taken as the melting point. The same applies to the other resins described below. MFR is measured according to JIS-K-7210 (condition: 230 ° C., load 21.18 N (2.16 kg). When the melting point of polypropylene is within this range, the second component described later shrinks heat. The heat shrinkage of the first component does not occur or is small even if it occurs at a temperature, and the desired three-dimensional crimping is well expressed. Further, when the melt flow rate is within the above range, the spinnability at the time of fiber production is good. Is.

The first component preferably contains polypropylene in an amount of 50% by mass or more, and more preferably 70% by mass or more. Alternatively, the first component does not contain other thermoplastics and may consist substantially of polypropylene alone. When the first component contains another thermoplastic resin, the other thermoplastic resin may be a polyolefin-based elastomer 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, including linear low density polyethylene) and the like may be one or more resins selected from polyolefin resins and the like.

The second component contains a propylene-α-olefin copolymer. Here, the α-olefin is ethylene or an α-olefin having 4 to 20 carbon atoms (excluding propylene). In the propylene-α-olefin copolymer, there may be only one α-olefin, in which case it becomes a binary copolymer. Alternatively, the number of α-olefins constituting the copolymer may be 2 or more, and in that case, the copolymer is ternary or more. In the propylene-α-olefin copolymer, the content of α-olefin 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 more and 7 by mass. It is particularly preferable that it is mass% or less, and most preferably 1.5 mass% or more and 6.6 mass% or less.

In the present embodiment, the second component is a propylene / ethylene copolymer having an ethylene content of 1% by mass or more and 15% by mass or less as a propylene-α-olefin copolymer (hereinafter, simply “propylene / ethylene copolymer”). ”) Is preferably included. A propylene / ethylene copolymer having an ethylene content within this range is likely to shrink by heat treatment at, for example, about 120 ° C to about 140 ° C, and is likely to satisfactorily develop a desired three-dimensional crimp in a composite fiber. When the ethylene content is less than 1% by mass, the content of ethylene contained in the propylene-ethylene copolymer decreases, so that the properties of the propylene-ethylene copolymer are the same as those of the propylene homopolymer. Therefore, when the first component and the second component are compared, the difference in the heat shrinkage ratio tends to be small, and the heat shrinkage property of the composite fiber tends to be small. When the ethylene content exceeds 15% by mass, steric crimps are excessively expressed, that is, the amount of heat shrinkage associated with the steric crimps during heat treatment becomes extremely large, and the formation of fiber aggregates such as batting becomes It may be worse, or the density of the fiber aggregates may increase and the drapeability may decrease. The ethylene content may be 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 5% by mass or less.
The propylene / ethylene copolymer may be either a random copolymer or a block copolymer. Considering heat shrinkage, a random copolymer is preferable.

The propylene / ethylene copolymer may have, for example, a melting point before spinning in the range of 130 ° C. to 148 ° C., or may be in the range of 135 ° C. to 145 ° C. The melt flow rate (MFR; measurement temperature 230 ° C., load 21.18 N (2.16 kgf)) before spinning is preferably 50 g / 10 minutes or less, preferably 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 steric crimp is easily developed by heat treatment at about 100 ° C. to 140 ° C. Further, when the melt flow rate is within this range, the spinnability at the time of 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 the propylene / 1-butene / ethylene copolymer (hereinafter, simply referred to as “propylene / 1-butene / ethylene copolymer”) is preferably contained. A propylene / 1-butene / ethylene copolymer having a content of 1-butene and ethylene in the above range is also similar to the propylene / ethylene copolymer described above, for example, 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 with the composite fiber.

When the 1-butene content is less than 0.1% by mass or the ethylene content is less than 1% by mass, the heat shrinkage tends to be small. When the 1-butene content exceeds 3.5% by mass or the ethylene content exceeds 7% by mass, excessive steric crimping occurs, that is, the amount of heat shrinkage associated with the steric crimping during heat treatment is very large. As the size increases, the texture of the fiber aggregates such as batting may deteriorate, or the density of the fiber aggregates may increase and the drape property may decrease. The 1-butene content may be 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 2.8% by mass or less.
The ethylene content may be 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 3 It may be 0.8% by mass or less. The propylene / 1-butene / ethylene copolymer may be either a random copolymer or a block copolymer. Considering the heat shrinkage, a random copolymer is preferable.

The propylene / 1-butene / ethylene copolymer may have, for example, a melting point before spinning in the range of 120 ° C. to 145 ° C., and may be in the range of 130 to 140 ° C. Further, 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 are particularly preferable. When the melting point of the propylene / ethylene copolymer is within this range, the desired steric crimp is easily developed by heat treatment at about 100 ° C. to 140 ° C. Further, when the melt index is within this range, the spinnability at the time of fiber production is good.

The second component preferably contains a propylene-α-olefin copolymer in an amount of 50% by mass or more, and more preferably 70% by mass or more. Alternatively, the second component does not contain other thermoplastic resins and may be substantially composed of only the propylene-α-olefin copolymer. When the second component contains another thermoplastic resin, the other thermoplastic resin may be a polyolefin-based elastomer described later, or as "another thermoplastic resin" in relation to the first component first. It may be one or more resins selected from the thermoplastic resins described.

The composite fiber of the present embodiment contains a polyolefin-based elastomer in either or both of the first component and the second component. By containing the polyolefin-based elastomer, the expression of excessive three-dimensional crimping in the composite fiber can be suppressed, and the entire fiber has appropriate elasticity, and the bulk reduction (sagging) with time when the batting is used. Can be suppressed.

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

The polyolefin-based elastomer may be contained only in the second component. As described above, since the second component contains a propylene-α-olefin copolymer which is a heat-shrinkable component, particularly a propylene / ethylene copolymer or a propylene / 1-butene / ethylene copolymer, the second component is a polyolefin-based component. When the elastomer is contained, it becomes easy to control the heat shrinkage of the second component, and it becomes easy to design the composite fiber so as to have a desired steric crimp.

As the polyolefin-based elastomer, one or more polyolefin resins selected from polyethylene, polypropylene, and a copolymer of propylene and an α-olefin having 4 or more carbon atoms, for example, 4 or more and 8 or less carbon atoms are used as hard segments. Examples thereof include thermoplastic elastomers having α-olefin rubber or other rubber as a soft segment. 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, 1-octadecene and the like. 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. Other rubbers that serve as soft segments include, for example, isoprene rubber, butadiene rubber, butyl rubber, propylene-butadiene rubber, acrylonitrile-butadiene rubber, and diene rubbers such as acrylonitrile-isoprene rubber.

The melting point of the polyolefin-based elastomer is not particularly limited, and may be, for example, 70 ° C. or higher and 170 ° C. or lower, preferably 100 ° C. or higher and 160 ° C. or lower. When the olefin-based elastomer is contained in the second component, its melting point is more preferably 160 ° C. or higher than the melting point of the propylene / α-olefin copolymer. When the melting point of the polyolefin-based elastomer is within the above range, the heat resistance is high, and for example, the bulk is unlikely to be reduced by heat treatment during the production of batting.

The melt flow rate (MFR; measurement temperature 230 ° C., load 21.18 N (2.16 kgf)) of the polyolefin-based elastomer is not particularly limited, and may be, for example, 1 g / 10 minutes or more and 30 g / 10 minutes, 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 at the time of fiber production is good.

In the present embodiment, the polyolefin-based elastomer may contain propylene as a hard segment and may be polymerized using a metallocene catalyst. In the polyolefin-based thermoplastic elastomer polymerized without using a metallocene catalyst, the crystalline and amorphous portions of the elastomer are dispersed in a size of 300 nm to 1 μm. When an elastomer in which hard segments and soft segments of this size are dispersed, the bending elasticity of the elastomer itself, the bending elasticity of the fibers containing the elastomer and the bulk recovery property are poor, and in addition, melt spinning becomes difficult. There is a tendency. On the other hand, in the polyolefin-based thermoplastic elastomer polymerized using a metallocene catalyst, the crystalline and amorphous portions of the elastomer are dispersed in a size of 5 to 50 nm. Composite fibers using this elastomer are rich in heat resistance, and tend to be excellent in bulk recovery property and strain resistance after repeated deformation.

Examples of the polyolefin-based elastomer that can be used in the present embodiment include "Milastomer (registered trademark)" and "Toughmer (registered trademark)" manufactured by Mitsui Chemicals Corporation, and "Esporex (registered trademark)" manufactured by Sumitomo Chemical Corporation. , "Thermoran (registered trademark)" and "Zeras (registered trademark)" manufactured by Mitsubishi Chemical Corporation, and "WELNEX (registered trademark)" manufactured by Japan Polypropylene Corporation, but are not limited thereto.

The composite fiber of the present embodiment preferably has a cross-sectional structure in which the second component is exposed at a length of 20% or more with respect to 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 the core component, the second component is the sheath component, and the position of the center of gravity of the first component (core component) is deviated from the position of the center of gravity of the fiber, and A side-by-side type cross section (also referred to as “parallel type 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 composite fiber having excellent shrinkage property and excellent crimping property.
When the heat-shrinkable composite fiber is an eccentric core-sheath type composite 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 referred to here is defined by the following equation.

The fiber cross-sectional shape (outer peripheral shape) of the composite fiber of the present embodiment may be circular, or may be irregular such as elliptical, Y-shaped, well-shaped, polygonal, or star-shaped. Further, the fiber cross section (outer peripheral shape) of the first component may be circular, or may be irregular such as elliptical, Y-shaped, well-shaped, polygonal, or star-shaped.

The composite ratio of the first component and the second component may be in the range of 3: 7 to 7: 3 in terms of volume ratio, preferably in the range of 4: 6 to 6: 4. If the proportion of the second component is too small, the fibers may not shrink sufficiently to develop the desired three-dimensional crimp. If the ratio of the second component is too large, the amount of heat shrinkage of the composite fiber becomes too large, so that the composite fiber is excessively heat-shrinked during the heat treatment, and the resulting fiber aggregate has a high density and low drape property. There is a risk of becoming. Further, since the ratio of the propylene-α-olefin copolymer, which is soft and has a low melting point, to the whole fiber is larger than that of polypropylene, the elasticity of the obtained fiber aggregate may be small.

As described above, the composite fiber in which two specific components are composited so as to have an eccentric core sheath type cross section or a side-by-side type cross section is sterically crimped at the fiber stage or by being subjected to heat treatment after fiber production. Will be expressed. Here, the term "three-dimensional crimp" is used to distinguish it from mechanical crimp in which the crest (or peak) of the crimp as shown in FIG. 3 has an acute angle. Further, "three-dimensional crimp is expressed" means, for example, a crimp in which the mountain portion is curved (wave-shaped crimp) as shown in FIG. 1A, and a spiral portion in which the mountain portion is curved as shown in FIG. In addition to corrugated crimps (spiral crimps), crimps with a mixture of wavy crimps and spiral crimps as shown in FIG. 1C, and mechanical crimps as shown in FIG. It refers to the occurrence of crimps in which at least one of crimps and spiral crimps is mixed.

The composite fiber of the present embodiment may be one that expresses three-dimensional crimping at the fiber stage. The composite fiber in which three-dimensional crimping is exhibited at the fiber stage can give a batting which is bulky even when used as it is without being subjected to heat treatment and whose bulk does not decrease with time. Alternatively, the composite fiber of the present embodiment may not develop three-dimensional crimping at the fiber stage, but may develop three-dimensional crimping by heating. Alternatively, the composite fiber of the present embodiment expresses three-dimensional crimping at the fiber stage, but further develops three-dimensional crimping by heating, or the degree of three-dimensional crimping already developed becomes stronger. It may be something like. A sheet-shaped batting obtained by producing a fiber web using a composite fiber in which three-dimensional crimping develops or becomes stronger by heating and subjecting the fiber web to heat treatment has elasticity. ..

When the composite fiber of the present embodiment develops three-dimensional crimping 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 may be there. When mechanical crimping and wavy crimping and / or spiral crimping are mixed and expressed in the composite fiber, mechanical crimping is also included in the number of three-dimensional crimping. The composite fiber of the present embodiment has a number of crimps of 15/25 mm or more and 90/25 mm or less, particularly 18/25 mm or more and 70/25 mm or less when three-dimensional crimp is developed by heat treatment. It's okay. The number of crimps is measured according to JIS L 1015. When many three-dimensional crimps are expressed in the composite fibers, the initial bulk of the batting containing the composite fibers tends to be small.

The composite fiber of the present embodiment does not exhibit excessive three-dimensional crimping even when heated. That means, for example,
1) Dry heat shrinkage measured under the conditions of a temperature of 140 ° C., a time of 15 minutes, and an initial load of 0.45 mN / dtex (hereinafter, “140 ° C. dry heat shrinkage rate”),
2) The initial load is 0.45 mN / dtex, and the temperature is raised from room temperature (18 ° C.) at a heating rate of 10 ° C. per minute. The temperature at which the sample length and the heat shrinkage rate are measured from the start of the temperature rise and the heat shrinkage rate integrated from the start of the temperature rise exceeds 1% (hereinafter, "1% heat shrinkage start temperature").
3) Dry heat shrinkage measured under the conditions of a temperature of 120 ° C., a time of 15 minutes, and an initial load of 0.018 mN / dtex (hereinafter, “120 ° C. dry heat shrinkage rate”).
Appears in.

The composite 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 composite fiber having a large heat shrinkage rate under a low load and a small heat shrinkage rate under a high load is the composite fiber of the present embodiment that does not exhibit excessive three-dimensional crimping. Such composite fibers undergo large heat shrinkage when no load (tension) is applied or when the applied load is small, but when a certain amount of load is applied, for example, card webs or fibers are entangled with each other. In a state where the fibers are fixed to some extent, such as a fiber sheet, the amount of heat shrinkage during heat treatment is suppressed, so that appropriate three-dimensional crimping is exhibited. Therefore, according to the composite fiber of the present embodiment, poor formation and a rapid decrease in bulk do not occur, the initial bulk of the fiber aggregate can be increased, and the fiber aggregate is caused by three-dimensional crimping. It will have resilience and cushioning properties.

The composite fiber of the present embodiment may have a dry heat shrinkage rate of 140 ° C. 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 in fibers in which three-dimensional crimping is unlikely to occur, that is, heat shrinkage is unlikely to occur. The 140 ° C. dry heat shrinkage rate of the composite fiber of the present embodiment may be 8% or less, 5% or less, 3% or less, or 0%. When the dry heat shrinkage rate at 140 ° C. is 0%, it means that the heat shrinkage cannot be confirmed by the measuring method.

The composite fiber of the present embodiment may have a 1% heat shrinkage start temperature of 100 ° C. or higher. Here, the 1% heat shrinkage start 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. Refers to temperature. The higher the 1% heat shrinkage start temperature, the greater the load applied to the fibers (when the fibers in the fiber aggregate are strongly entangled or bonded to each other), the fibers are less likely to shrink due to heat. Three-dimensional crimping is unlikely to occur in fibers having a composite form as in the embodiment. The 1% heat shrinkage start temperature of the composite fiber of the present embodiment may be 120 ° C. or higher, 130 ° C. or higher, or 135 ° C. or higher.

The composite fiber of the present embodiment has a dry heat shrinkage rate of 120 ° C. of 20% or more and 70% or less, preferably 30% or more and 60% or less, more preferably 35% or more and 55% or less, and particularly preferably 38% or more and 50% or less. It may have. Since the dry heat shrinkage rate at 120 ° C. of the composite fiber of the present embodiment is measured in a state where the initial load is small, it is suitable for observing the degree of three-dimensional crimping developed by heating. When the dry heat shrinkage rate at 120 ° C. is within this range, the degree of three-dimensional crimping caused by heating does not increase so much regardless of whether or not three-dimensional crimping occurs at the fiber stage, and heating is performed. Even when subjected to treatment, the initial bulk of the batting or fiber assembly containing this fiber can be increased.

The fineness of the composite fiber is not particularly limited, and is appropriately selected depending on the intended use and the like. For example, when used for batting, the composite fiber may have a fineness of 0.5dtex to 30dtex, preferably 0.8dtex to 20dtex, more preferably 1.1dtex to 18dtex. When the batting is composed of composite fibers having a fineness within the above range, it is easy to obtain a batting having excellent bulkiness and 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 composite fibers, the fiber length of the composite 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 used as a type of batting that is filled into bedding or the like by blowing, the fiber length of the composite fiber may be in the range of 20 mm to 120 mm. Alternatively, when the fibers are entangled with each other to form a fluff-like material and the aggregate is used as a 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. It may be in the range of 24 mm to 48 mm, or may be in the range of 28 mm to 42 mm. Alternatively, when a fiber web is produced using a card machine and, if necessary, a batting or a non-woven fabric in which the fibers are bonded to each other with a binder resin or the like is produced, 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 composite fiber of the present embodiment can be produced, for example, as follows.
First, polypropylene constituting the first component, and a propylene-α-olefin copolymer and a polyolefin-based elastomer constituting the second component are prepared. If necessary, other thermoplastic resins constituting the first component and the second component are prepared.

Next, the first component is melt-spun at a spinning temperature of 250 ° C. to 350 ° C. and the second component at a spinning temperature of 200 ° C. to 300 ° C. using an appropriate composite nozzle so that a desired fiber cross-sectional structure can be obtained. , Take-up 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 higher and lower than the melting point of the second component, and the stretching treatment is performed at a stretching ratio of 1.8 times or higher. When the second component contains a plurality of resins, the temperature of the resin having 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 a temperature 10 ° C. lower than the melting point of the second component. If the stretching temperature is less than 50 ° C., the crystallization of the second component is difficult to proceed, so that the heat shrinkage tends to be large and the bulk recovery property tends to be small. When the stretching temperature is equal to or higher than the melting point of the second component, the fibers tend to fuse with each other. The lower limit of the more preferable 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 the fiber in which the above-mentioned wavy crimp and / or spiral crimp is exhibited, and the initial bulk and the rigidity of the fiber itself are obtained. Does not get smaller.

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

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

Before and after the stretching treatment, for example, after mechanical crimping, annealing treatment is performed in an atmosphere such as dry heat, moist heat, or steam heat at 50 ° C to 120 ° C, preferably 60 ° C to 100 ° C, if necessary. You may. When the temperature during the annealing treatment is raised, the fibers can develop three-dimensional crimps, and fibers that develop three-dimensional crimps at the fiber stage can be obtained. When the annealing treatment is carried out after mechanical crimping is applied, it may also serve as a drying treatment of the fiber treatment agent. Then, it is cut to a predetermined fiber length.

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

The form of the batting is not particularly limited. For example, after fiber production, raw cotton mixed with other fibers as needed may be subjected to fiber opening treatment and then sprayed with a pressurized gas to fill the product as it is, or to fill a bag-like product. You can. The batting in the form of being filled in a bag-shaped material is used by attaching the bag-shaped material to clothing or the like. When the opened fibers are used as batting as they are, the composite fibers of the present embodiment may exhibit three-dimensional crimping at the fiber stage, in which case the initial bulk is larger and the decrease in bulk over time is smaller. You can get batting. Alternatively, when the composite fiber of the present embodiment does not develop three-dimensional crimping at the fiber stage, it may be subjected to heat treatment to develop three-dimensional crimping before filling. Alternatively, even if the composite fiber of the present embodiment is filled in a product or the like as a batting without exhibiting three-dimensional crimping, the resulting batting has elasticity due to the inclusion of the polyolefin-based elastomer, so that the obtained batting can be obtained over time. The reduction in bulk is less.

The batting may also be in the form of an aggregate of fluffy objects in which fibers are entangled with each other. This form of batting can be produced by using a processing machine that processes the opened raw cotton into a fluff shape. When producing fluffy batting, the composite fibers of the present embodiment may exhibit three-dimensional crimping at the fiber stage, in which case the batting has a larger initial bulk and less decrease in bulk over time. Obtainable. Alternatively, when the composite fiber of the present embodiment does not develop three-dimensional crimping at the fiber stage, it may be subjected to heat treatment to develop three-dimensional crimping before being processed into a fluffy substance. Alternatively, even if the composite fiber of the present embodiment is processed into a fluff-like material without exhibiting three-dimensional crimping, the fiber has elasticity due to the inclusion of the polyolefin-based elastomer, so that the resulting batting can be obtained over time. The reduction in bulk will be less.

Alternatively, the batting may be in sheet form. For example, after mixing the composite fiber of the present embodiment with other fibers as needed, a fiber web may be produced by a card machine or the like to form a sheet, and the sheet may be used as it is as batting. The sheet-shaped batting may be a laminated body composed of a plurality of sheet-like materials. In the sheet-shaped batting, when the composite fiber of the present embodiment expresses three-dimensional crimping, the initial bulk of the batting is larger and the decrease in bulk over time is smaller. Alternatively, even if the composite fiber of the present embodiment constitutes a sheet-shaped batting without expressing three-dimensional crimping, the fiber has elasticity due to the inclusion of the polyolefin-based elastomer, so that the obtained batting can be obtained over time. The reduction in bulk will be less.

In the sheet-shaped batting, the fibers may be adhered to each other. Adhesion may be by a heat-adhesive fiber different from the composite fiber of the present embodiment (a fiber in which some or all of the constituents are melted or softened when heated to exhibit adhesiveness). Alternatively, it may be made of a binder resin (resin bond), or it may be made of one component of the composite fiber of the present embodiment.

The heat-adhesive fiber preferably has a component having a melting point lower than the melting point of the component constituting the composite fiber of the present embodiment as the adhesive component. The heat-adhesive fiber may be, for example, a single fiber or a composite fiber in which polyethylene (including high density polyethylene, low density polyethylene, and linear low density polyethylene) occupies at least a part of the fiber surface. As the binder resin, resins used in the production of batting, for example, acrylic-based and polyurethane-based resins may be arbitrarily used. When the batting is in the form of fibers bonded to each other, it is preferable to bond them with heat-adhesive fibers or a binder resin. According to these means, the fibers can be adhered to each other by heat treatment at a relatively low temperature (for example, 120 ° C. to 150 ° C.).

The bonding treatment with a heat-adhesive fiber or a binder resin or one component of the composite fiber of the present embodiment is usually a heat-bonding treatment, but other bonding treatments such as electron beam irradiation or sonication may be performed. .. During the heat bonding treatment, the composite fibers of the present embodiment are exposed to heat to develop three-dimensional crimping. Therefore, the obtained batting has morphological retention due to thermal adhesion between the fibers, and has elasticity due to the developed three-dimensional crimp. Such batting is suitable for, for example, the batting of a jacket containing a batting based on a knitted fabric, and can expand and contract in accordance with the expansion and contraction of the knitted fabric. As will be described later, when a sheet-shaped batting is manufactured by a method of producing a fiber web and then heat-treating, when the heat treatment does not involve heat adhesion, the degree of freedom of the fibers is large and a more flexible batting can be obtained. Be done.

The sheet-shaped batting is used to prepare a fiber web containing 10% by mass or more of the composite fibers of the present embodiment, and to heat-treat the fiber web to develop three-dimensional crimp in the composite fiber, and / or already to develop it. It may be manufactured by a manufacturing method including increasing the degree of three-dimensional crimping. The heat treatment may involve thermal adhesion. Alternatively, the heat treatment may be carried out without heat adhesion only to cause the composite fiber to develop three-dimensional crimp and / or to increase the degree of three-dimensional crimp expressed in the composite fiber.

Adhesion between the fibers may be a thermal adhesion treatment that heats the fiber web to which the binder resin is attached. The binder resin may be attached to the fiber web by, for example, a spray method. The amount of adhesion may be, for example, 5% by mass to 100% by mass of the fiber web.

When the heat-adhesive fibers are mixed to produce a fiber web, the adhesive treatment may be a heat treatment, and the heat treatment may be performed so that the heat-adhesive fibers are softened or melted. When the heat-adhesive fibers are mixed, the proportion of the heat-adhesive fibers in the fiber web may be, for example, 10% by mass to 90% by mass.

The basis weight of the sheet-shaped batting is not particularly limited, and is appropriately selected depending on the intended use and the like. For example, when using a sheet-like filling a cotton ^{jacket, 15g / m 2 ~150g / m} 2 of basis weight, preferably have a basis weight of ^{20g / m 2 ~120g / m 2} . The sheet-like batting, for example, has a specific volume of 30cm ³ / g~5000cm ³ / g, preferably a specific volume of 50cm ³ / g~2500cm ³ / g. The specific volume is an index indicating the bulkiness of the batting, and if it is too small, the bulk of the batting may be too small to obtain the functions required for the batting such as sufficient warmth and cushioning.

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

In any form, the batting containing the composite fiber of the present embodiment preferably contains 10% by mass or more of the composite fiber of the present embodiment, preferably 20% by mass or more, and more preferably 30% by mass or more. Alternatively, the batting may be composed only of the composite fibers 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. Synthetic 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. The synthetic fiber may be either a single fiber or a composite fiber. As described above, in the sheet-shaped batting, when the fibers are bonded to each other by the heat-adhesive fiber, the heat-adhesive fiber is used as another fiber.
Alternatively, the other fibers may be natural fibers such as cotton, silk, wool, hemp, and pulp, and regenerated fibers such as rayon, cupra, and solvent-spun cellulose fibers. Alternatively, the composite fibers of this embodiment may be used together with feathers (down, feather).

The batting containing the composite fiber of the present embodiment includes clothing such as various cold protection clothes such as jackets and vests, bedding such as beds, mattresses, comforters, bed mats, mattresses, and pillows, stuffed animals, and cushioning materials (for example, for automobiles, Cushioning materials for aircraft, railroad vehicle, and marine seats, as well as cushioning materials and clothing pads for general household and office seats (eg, women's brassiere pads, shoulder pads, etc.) It may be used as an elbow pad, a knee pad, etc.), a knee pad, and a heat insulating material, a heat insulating material, a sound absorbing material, a sound insulating material, a vibration isolating material, and the like.

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

The fiber assembly may be, for example, a woven fabric, a knitted fabric or a non-woven fabric, in particular a non-woven fabric. The non-woven fabric may be, for example, a heat-adhesive non-woven fabric in which fibers are heat-bonded with a heat-adhesive fiber or a binder, and an entangled non-woven fabric in which fibers are entangled with each other. The non-woven fabric containing the composite fiber of the present embodiment is bulkier and has less decrease in bulk over time. Further, the non-woven fabric containing the composite fiber of the present embodiment can exhibit elasticity by the three-dimensional crimping expressed in the composite fiber. In particular, after the fiber web is prepared, entanglement treatment (for example, needle punching treatment or high-pressure fluid flow treatment) is performed as necessary, and then heat treatment is performed to cause the composite fiber to develop three-dimensional crimping, and / or already. The non-woven fabric produced by the method of increasing the degree of three-dimensional crimping shows higher elasticity.

The fiber assembly containing the composite fibers of the present embodiment is impregnated with sanitary articles such as masks, supporters and bandages; absorbent articles such as disposable diapers, sanitary napkins, and sheets for cages; and liquids such as cosmetics. Liquid-impregnated skin coating sheet (for example, face mask, keratin care sheet, decollete sheet, etc.); wiper; wet tissue; cushioning material; main body of packaging material, or the surface of the constituent members (for example, absorbent article). Suitable for sheets).

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

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

(Polyolefin-based elastomer)
PPR-A: Made by Japan Polypropylene Corporation, trade name WELNEX, melting point 150 ° C, MI 30 g / 10 minutes, polypropylene elastomer with nano-dispersed rubber component PPR-B: manufactured by Mitsui Chemicals, Inc., trade name Toughmer BL20300, melting point 150 ℃, MI 30g / 10 minutes, polypropylene elastomer with nano-dispersed rubber component

(Examples 1 to 7, Comparative Examples 1 to 3)
From the above thermoplastic resins, the resins shown in Tables 1 and 2 were selected as constituting the first component and the second component, respectively. Using an eccentric core sheath type composite nozzle with the first component as the core component and the second component as the sheath component, and setting the composite ratio (volume ratio) of the first component / second component to 5/5, both the sheath component and the core component The spinning filament was melt-extruded at a spinning temperature of 270 ° C. and a take-up speed of 280 m / min. To obtain a spun filament having an eccentricity shown in Tables 1 and 2 and having a fineness of 20 dtex.

The spun filament was stretched 3.5 times in warm water at 70 ° C. to obtain a drawn filament having a fineness of 6.7 dtex. Next, after applying the fiber treatment agent, the drawn filament was mechanically crimped at 16 pieces / 25 mm with a stuffing box type crimper. Next, the annealing treatment and the drying treatment were simultaneously carried out for 15 minutes in a hot air penetrating heat treatment machine set at 70 ° C., and the filament was cut to a fiber length of 38 mm to obtain a composite fiber. All of the obtained composite fibers exhibited three-dimensional crimping at the fiber stage.

With respect to 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 adopted in the examples was used as a sample, and a molecular weight distribution curve was obtained using a high-temperature GPC apparatus (Polymer Laboratories, PL-220). It was. The number average molecular weight Mn and the weight average molecular weight Mw were obtained from the molecular weight distribution curve, and the Q value was further obtained. The measurement conditions and the like are as follows.
Detector: Differential Refractometer Detector RI
Columns: Shodex HG-G (1), HT-806M (2) (Showa Denko)
Solvent: 1,2,4-trichlorobenzene (TCB) (with 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 amount: 0.200 mL
Standard sample: Monodisperse polystyrene (manufactured by Tosoh)
Data processing: GPC data processing system (manufactured by TRC)

For the obtained fibers, the box test settling described below was measured in order to evaluate the change in bulk over time.
(Box test)
Prepare 30 g of short fibers opened using a parallel card. This spread cotton is filled in an acrylic cylindrical box (diameter of the 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 mixture is left for 30 minutes with a load of 450 gf applied to the short fibers in the box. After 30 minutes, remove the weight and acrylic lid, measure the thickness of the spread cotton 30 minutes after weight removal with a metal straightedge, and measure the thickness reduction rate with respect to the initial thickness. The rate of dripping) is calculated by the following formula.
Settlement rate (%) = [(Initial thickness (mm) -30 minutes after weight removal (mm)) / Initial thickness (mm)] x 100

In addition, the heat shrinkage characteristics of the obtained fibers were evaluated by the method described below.
(140 ° C dry heat shrinkage rate)
Measured according to JIS L 1015. The initial load was 0.45 mN / dtex (50 mg / de), and the shrinkage rate was measured by dry heat treatment at a temperature of 140 ° C. for 15 minutes. The 140 ° C. dry heat shrinkage rate was calculated according to the following formula.
140 ° C. Dry heat shrinkage rate (%) = [(Sample length before dry heat treatment-Sample length after dry heat treatment) / (Sample length before dry heat treatment)] x 100

(1% heat shrinkage start temperature)
As with the 140 ° C. dry heat shrinkage rate, the measurement is performed according to JIS L 1015. The initial load is 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 raised from room temperature (18 ° C.) at a heating rate of 10 ° C. per minute. Measure the sample length and heat shrinkage at each temperature from the start of temperature rise. The temperature is continued until the integrated heat shrinkage rate exceeds 1% from the start of the temperature rise, and the temperature at which the integrated heat shrinkage rate exceeds 1% from the start of the temperature rise is defined as the 1% heat shrinkage start temperature.

(120 ° C dry heat shrinkage rate)
According to JIS L1015, the gripping interval was 100 mm, the treatment temperature was 120 ° C., the treatment time was 15 minutes, and the dry heat shrinkage rate was measured at 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 rate (%) = [(Sample length before dry heat treatment-Sample length after dry heat treatment) / (Sample length before dry heat treatment)] x 100

(Fiber web thickness before heat processing, fiber web thickness after heat 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) have a polypropylene single fiber ratio of 70% by mass (Example, comparison). The composite fibers of the example are mixed so as to be 30% by mass), and after the cotton is mixed, the fibers are opened using a parallel card machine to obtain a fiber web having a grain size of 80 g / m ² , and the thickness of this web is unloaded. Measured with a metal straightedge. The fiber web was heat-treated for 120 seconds with a hot air penetrating heat treatment machine set at 120 ° C. The thickness of the fiber web after heat treatment is measured with a metal straightedge with no load. The basis weight of the fiber webs after the heat treatment was 100 g / m ² .

Tables 1 and 2 show the box test of the composite fibers of each example and each comparative example, and the heat shrinkage characteristics.

All of the composite fibers of Examples 1 to 7 had a small box test settling rate and a small decrease in bulk over time. In addition, the fibers of Examples 1 to 5 in which the second component was a propylene / ethylene copolymer had a dry heat shrinkage rate of 0% at 140 ° C. and a 1% heat shrinkage start 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 a dry heat shrinkage rate of 140 ° C. of 3.0% and 5.0%, respectively, and a 1% heat shrinkage start. The temperatures were 137 ° C and 134 ° C, respectively. As is clear from these facts, the composite fibers of Examples 1 to 7 have smaller heat shrinkage than the fibers of Comparative Examples, and are finely three-dimensionally wound when the fibers are subjected to heat treatment after being prepared. It was hard to shrink. This is supported by the large thickness of the web after heat processing and the small dry heat shrinkage rate at 120 ° C., especially for the fibers of Examples 1 to 5. That is, the composite fibers of Examples 1 to 7 could provide batting showing a relatively large initial bulk even after heat processing.

Since the fiber of Comparative Example 1 did not contain a polyolefin-based elastomer, it had a large box test settling, a large heat shrinkage property, and a large number of fine three-dimensional crimps were exhibited by heating. Therefore, the web thickness after heat processing using the fibers of Comparative Example 1 was the smallest among the Examples and Comparative Examples. Since the proportion of the polyolefin-based elastomer contained in the second component of the fiber of Comparative Example 2 was small, the box test settling was slightly large, the heat shrinkage was large, and a large number of fine three-dimensional crimps were exhibited by heating. The web thickness was small after heat processing. Since the Q value of polypropylene as the first component was small, the fiber of Comparative Example 3 had high heat shrinkage, easily developed fine three-dimensional crimping by heating, and had a small web thickness after heat processing.

The present invention includes the following aspects.
(Aspect 1)
A propylene-α-olefin copolymer and a first component containing polypropylene having a Q value (ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn)) of 3.5 or more and 6.5 or less. Consists of a second component containing
One or both of the first component and the second component contains a polyolefin-based elastomer.
An eccentric core sheath type fiber 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 is deviated from the center of gravity of the fiber, or the first component and the above. It has a side-by-side type fiber cross section to which the second component is bonded,
In the component containing the polyolefin-based elastomer, the proportion of the polyolefin-based elastomer is 10% by mass or more and 30% by mass or less.
Composite fiber.
(Aspect 2)
The composite fiber of aspect 1, wherein the polyolefin-based elastomer is contained only in the second component.
(Aspect 3)
The composite fiber of aspect 1 or 2, wherein the polyolefin-based elastomer is a polyolefin-based elastomer containing a 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-α-olefin 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. -A composite fiber according to any one of aspects 1 to 3, which is an ethylene copolymer.
(Aspect 6)
A composite fiber according to any one of aspects 1 to 5, which has three-dimensional crimping.
(Aspect 7)
Measured under the conditions of temperature 140 ° C., time 15 minutes, initial load 0.45 mN / dtex The dry heat shrinkage rate is 10% or less, and measured under the conditions of temperature 120 ° C., time 15 minutes, initial load 0.018 mN / dtex. The composite fiber according to any one of aspects 1 to 6, wherein the dry heat shrinkage rate is 20% or more and 70% or less.
(Aspect 8)
A fiber assembly comprising 10% by mass or more of the composite fibers according to any one of aspects 1 to 7.
(Aspect 9)
A batting containing 10% by mass or more of the composite fiber according to any one of aspects 1 to 7.
(Aspect 10)
The batting of aspect 9 in which the fibers are adhered to each other.
(Aspect 11)
The batting of aspect 9, which is an aggregate of fluffy objects formed by entwining fibers.
(Aspect 12)
To prepare a fiber web containing 10% by mass or more of the composite fibers according to any one of aspects 1 to 7.
A method for producing a batting, which comprises subjecting the fiber web to heat treatment to develop three-dimensional crimping in the composite fiber and / or to increase the degree of three-dimensional crimping already developed.
(Aspect 13)
The method for producing batting according to aspect 12, further comprising attaching a binder resin to the fiber web, wherein the heat treatment is a heat bonding treatment for heating the fiber web to which the binder resin is attached.

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

Claims (13)

A propylene-α-olefin copolymer and a first component containing polypropylene having a Q value (ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn)) of 3.5 or more and 6.5 or less. Consists of a second component containing
Before Stories second Ingredient comprises a polyolefin elastomer,
The first component is a core component, the second component is a sheath component, and the center of gravity of the first component has an eccentric core sheath type fiber cross section deviated from the center of gravity of the fiber.
In the second component containing the polyolefin-based elastomer, the proportion of the polyolefin-based elastomer is 10% by mass or more and 30% by mass or less.
Composite fiber. The composite fiber according to claim 1, wherein the polyolefin-based elastomer is contained only in the second component. The composite fiber according to claim 1 or 2, wherein the polyolefin-based elastomer is a polyolefin-based elastomer containing a propylene and a metallocene catalyst. The composite 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-α-olefin 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 composite fiber according to any one of claims 1 to 5, which has three-dimensional crimping. Measured under the conditions of temperature 140 ° C., time 15 minutes, initial load 0.45 mN / dtex The dry heat shrinkage rate is 10% or less, and measured under the conditions of temperature 120 ° C., time 15 minutes, initial load 0.018 mN / dtex. The composite fiber according to any one of claims 1 to 6, wherein the dry heat shrinkage rate is 20% or more and 70% or less. A fiber aggregate containing 10% by mass or more of the composite fiber according to any one of claims 1 to 7. A batting containing 10% by mass or more of the composite fiber according to any one of claims 1 to 7. The batting according to claim 9, wherein the fibers are adhered to each other. The batting according to claim 9, which is an aggregate of fluffy objects formed by entwining fibers. To prepare a fiber web containing 10% by mass or more of the composite fiber according to any one of claims 1 to 7.
A method for producing a batting, which comprises subjecting the fiber web to heat treatment to develop three-dimensional crimping in the composite fiber and / or to increase the degree of three-dimensional crimping already developed. The method for producing batting according to claim 12, further comprising adhering a binder resin to the fiber web, wherein the heat treatment is a heat bonding treatment for heating the fiber web to which the binder resin is attached.

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