TWI575128B - Sponetaneously crimping conjugate short fiber and manufacturing method thereof, fiber aggregates and sanitary articles - Google Patents

Description

Significantly crimped composite staple fiber, method for producing the same, fiber assembly and sanitary article

The present invention relates to a remarkable crimped composite short fiber excellent in spinnability and processability (especially high-speed carding property), and has good surface feel, softness in a thick direction, and elasticity using the fiber. An excellent fiber assembly, and a sanitary article using the fiber assembly.

In the past, a composite fiber composed of two or more kinds of components has been proposed as a composite fiber comprising polyethylene as a main component and having at least a part of the surface of the composite fiber. Such a composite fiber is continuously improved for the purpose of further improving the touch and softness of a fiber-derived product (especially a non-woven fabric) and further improving thermal adhesion by polyethylene.

For example, Patent Document 1 (JP-A-2008-264473) proposes a crimped conjugate fiber comprising a first component containing a linear polyethylene polymer polymerized using a metallocene catalyst, The two components are a composite fiber of a polyester containing 50% by mass or more of polytrimethylene terephthalate, wherein the position of the center of gravity of the second component is deviated from the position of the center of gravity of the composite fiber, and the composite fiber has a wave The crimp and the spiral crimp select at least one of the crimps. The conjugate fiber proposed in Patent Document 1 is very soft and exhibits an excellent initial volume recovery rate because its second component contains polytrimethylene terephthalate as a main component.

Patent Document 2 (JP-A-63-105111) proposes a composite heat-fusible fiber characterized by two components having different melting points. In the composite heat-bonding fiber which is arranged concentrically or in parallel, one of the aforementioned components is a low-melting component of adding 2 to 20% of linear low-density polyethylene or low-density polyethylene to high-density polyethylene. In addition, the other component has a resin having a melting point higher than the low melting point component by 20 ° C or higher and having a fiber forming ability as a high melting point component. The conjugate fiber described in this document has a wide range of welding conditions, and a non-woven fabric having stable swell strength and feel can be obtained even if the production conditions and external air conditions fluctuate.

Patent Document 3 (JP-A-H11-350255) proposes a sheath having a high melting point and a low melting point and having a polyethylene resin (A) having a low melting point at least 5 ° C lower than the high melting point, and having a ratio a core-sheath type composite fiber composed of a core portion of a high melting point resin (B) having a melting point higher than a melting point of 10 ° C or higher, or a polyethylene resin portion obtained by a polyethylene resin (A), And a side by side type composite fiber composed of a high melting point resin portion formed by the high melting point resin (B). The conjugate fiber described in this document is suitable for a wide processing temperature. Therefore, when the web formed by the fiber is entangled by hot embossing, it can be prevented from being attached to the heat roller and poorly fused, and is hot embossed. Excellent sex.

Patent Document 4 (Japanese Patent No. 4315663) proposes a method for producing a nonwoven fabric characterized by using a polyester and a first polyethylene obtained by a metallocene polymerization catalyst with Ziegler-Nano a second polyethylene-mixed polyethylene obtained by a Ziegler-Natta polymerization catalyst is supplied to the core-sheath type composite spinning hole and melt-spun in such a manner that the polyester is disposed in the core portion and the polyethylene is disposed on the sheath portion. The core is composed of the polyester and The sheath portion is made of the polyethylene, and a core-sheath composite long fiber in which the cross-sectional shape of the core is substantially unchanged in the fiber axis direction, and the thickness of the sheath portion is uneven and randomly changed in the fiber axis direction and the fiber circumferential direction is obtained. Then, the core-sheath composite long fibers are accumulated. According to this production method, a long fiber nonwoven fabric in which the fiber diameter of the long fiber is not fixed, the flexibility is excellent, or the heat sealability is excellent can be obtained.

[references] (Patent Literature)

Patent Document 1: Japanese Laid-Open Patent Publication No. 2008-264473

Patent Document 2: Japanese Laid-Open Patent Publication No. SHO63-105111

Patent Document 3: Japanese Patent Laid-Open No. Hei 11-350255

Patent Document 4: Japanese Patent No. 4315663

A fiber product (especially a non-woven fabric) made of a composite fiber comprising polyethylene as a main component and having at least a part of the surface of the composite fiber is widely used as a sanitary article such as sanitary napkins and disposable diapers. Surface material. Since the surface material of the sanitary article is in direct contact with the delicate part of the human body or the animal, it is strongly required that the surface material itself has an excellent touch. This requirement has been continuously improved in recent years. Specifically, in addition to a good surface feel (smooth feeling when the surface is touched), the surface material is required to have a soft and fluffy feeling in the thickness direction, that is, a bulkiness is required, and it is easily deformed when a force is applied in the thickness direction. The nature, that is, the softness of the thickness direction and the feeling of the cushioning property of the rebound feeling when the force is applied in the thickness direction, in other words, the body is required Product recovery.

In addition, not only the surface material of the sanitary article but also the fiber product from the fiber is also expected to be produced as efficiently as possible. An indicator of productivity can be, for example, high-speed carding in the case of manufacturing a nonwoven fabric. When making non-woven fabrics, when the short fibers are opened by the carding machine and the net is made, the knotting and the unevenness of the cloth are not generated according to the made net, and the speed of the net is made (in every 1 minute) The scale indicates how high the combing property can be determined. In the non-woven mass production site, for example, a high-speed combing property of 100 m/min is required.

It is not easy to obtain a composite staple fiber which has a good touch and is excellent in high-speed carding. For example, the significantly crimpable composite fiber described in Patent Document 1 is relatively soft, but has a problem of high-speed combing property deterioration. The fibers described in Patent Documents 2 and 3 are not soft because of the use of high-melting polyethylene, and the fiber assembly obtained by using the fiber does not exhibit a good touch (especially a surface touch). Patent Document 4 obtains a long-fiber nonwoven fabric having a special shape, whereby flexibility can be achieved. However, if fibers having an unfixed fiber diameter, such as short fibers, are passed through the combing, the fibers cannot smoothly pass through the combing, thereby causing knotting and Uneven quality.

The present invention has been made in view of the facts of the present invention in order to obtain a composite fiber having a good tactile sensation and excellent high-speed combing property.

The present invention provides a remarkably crimped composite staple fiber comprising a composite staple fiber of a first component and a second component, wherein the first component comprises a linear polyethylene having a density of from 0.90 g/cm ³ to 0.94 g/cm ³ And low-density polyethylene, and the low-density polyethylene is contained in the first component such that the low-density polyethylene accounts for 5% by mass to 25% by mass of the total mass of the linear polyethylene and the low-density polyethylene. The second component contains 50% by mass or more of a polyester having a melting point higher than a melting point of a linear polyethylene constituting the first component by 40 ° C or higher, and the first component occupies at least 20 of the fiber surface in the fiber cross section. %, the position of the center of gravity of the second component is offset from the center of gravity of the composite fiber; and the composite staple fiber has at least one crimp selected by wave-shaped crimping and spiral crimping.

The present invention provides a method of producing a substantially crimped composite staple fiber. That is, a method for producing a composite short fiber, which is a method for producing a composite short fiber comprising a first component and a second component, comprising: linearly polymerizing a density of from 0.90 g/cm ³ to 0.94 g/cm ³ Ethylene and low-density polyethylene, and the low-density polyethylene accounts for 5% by mass to 25% by mass of the first component of the total mass of the linear polyethylene and the low-density polyethylene, and has a content of 50% by mass or more. a second component of the polyester constituting the first component of the linear polyethylene having a melting point higher than 40 ° C, such that in the fiber cross section, the first component accounts for at least 20% of the surface of the fiber, and the position of the center of gravity of the second component Melting spinning in a manner deviating from the position of the center of gravity of the fiber, and obtaining a spinning filament having a spinning filament at a temperature of Tg ₂ ° C to 95 ° C (but having a polymer component contained in the second component of the Tg ₂ system) The temperature within the range of the glass transition point of the polymer component of the highest glass transition point extends 1.8 to 5 times, and for the extended filament, the mechanical crimp is imparted in the range of 5 peaks / 25 mm to 25 peaks / 25 mm. Annealing treatment at a temperature in the range of 50 to 115 ° C Cutting the annealed filaments of a length of 1mm to 100mm; and the composite staple fiber having a crimp and spiral crimp wave form of at least one selected crimps.

The present invention further provides a fiber assembly containing 20% by mass or more of the above-mentioned remarkable crimped composite short fiber. The fiber assembly is preferably a non-woven fabric, more preferably a heat of the first component followed by a non-woven fabric.

The present invention provides a surface material for a sanitary article which is formed from the aforementioned fiber assembly. The present invention further provides a sanitary article which is added to the aforementioned surface material.

The significantly crimped composite staple fiber of the present invention, the first component comprising a linear polyethylene having a density of 0.90 g/cm ³ to 0.94 g/cm ³ and a prescribed amount of low density polyethylene; the second component comprising 50 mass More than % of the polyester, and the second component deviates from the center of gravity; and the significantly crimped composite staple fiber has at least one crimp selected by wave-shaped crimping and spiral crimping. The remarkable crimping composite short fiber has excellent combing property, and can be obtained as a carding net with excellent cloth quality, and the fiber assembly (especially non-woven fabric) containing the fiber has good surface touch, and has fluffiness and thickness. Excellent flexibility and volume recovery in the direction. Further, the remarkably crimped composite short fiber is made of two types of polyethylene, whereby heat treatment can be carried out in a wide temperature range in the case of producing heat and then non-woven fabric. Therefore, the remarkably crimped composite staple fiber is suitable for a product which is in direct contact with a delicate part of a human body or an animal which constitutes a surface material of a sanitary article, and can be manufactured with high productivity.

The fiber assembly (especially non-woven fabric) containing the composite short fibers obtained by the method for producing the remarkably crimped conjugate fiber of the present invention has a good surface feel, and is excellent in bulkiness, flexibility in the thickness direction, and volume recovery property. Therefore, according to the above-described manufacturing method, the composite short fibers can be produced with high productivity, and the composite short fibers are suitable for the articles which constitute the surface material of the sanitary article and which are in direct contact with the delicate portions of the human body or the animal.

In order to achieve the above object, the present inventors considered that in the conjugate fiber, the low-melting component ensures the softness and thermal adhesion of the fiber, and the high-melting component ensures the bulkiness and volume recovery of the non-woven fabric, and must provide high-speed carding. rigidity. Here, it is reviewed that the low-melting component is composed of a linear polyethylene having a good surface feel, and the high-melting component is composed of a polyester, and a significantly crimped composite fiber having a three-dimensional crimp is obtained. However, such a fiber is excellent in surface touch feeling, but is not sufficient in high-speed carding property, bulkiness as a non-woven fabric, flexibility in a thickness direction, and volume recovery property. Here, the improvement of the low melting point component is reviewed in the range of the surface touch without impairing the linear polyethylene.

As a result of the review, it was found that by adding a small amount of low-density polyethylene to a linear polyethylene having a density higher than a predetermined value, a good surface feel is not impaired by the linear polyethylene, and high-speed carding can be obtained. It is excellent in composite properties, and is a composite short fiber which has excellent bulkiness, flexibility in the thickness direction, and volume recovery property when it is not woven. Therefore, the remarkably crimped composite short fiber of the present invention is a remarkably crimped composite short fiber having a first component containing a linear polyethylene having a density of 0.90 g/cm ³ to 0.94 g/cm ³ and a low density. Polyethylene, and the first component contains low density polyethylene in such a manner that the low density polyethylene accounts for 5% by mass to 25% by mass of the total mass of the linear polyethylene and the low density polyethylene; the second component a polyester containing 50% by mass or more, the polyester having a melting point higher than a melting point of a linear polyethylene constituting the first component by 40 ° C or more, and a first component of the fiber cross section of at least 20% of the surface of the fiber, second The center of gravity of the component is offset from the center of gravity of the composite fiber; and the composite staple fiber has at least one crimp selected by wave-shaped crimping and helical crimping. The first component and the second component constituting the composite short fiber will be described below.

The first component contains a linear polyethylene having a density of 0.90 g/cm ³ to 0.94 g/cm ³ and a low density polyethylene. Linear polyethylene (also referred to as "LLDPE (Linear Low Density Polyethylene)", but the linear polyethylene used in the present invention is not limited to a low density (generally 0.925 g/cm ³ or less). a copolymer obtained by copolymerization with an α-olefin. The α-olefin is generally an α-olefin having 3 to 12 carbon atoms. Specific examples of the α-olefin having 3 to 12 carbon atoms include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, and 1- Octene, 1-decene, 1-decene, 1-dodecene, and mixtures thereof. Particularly preferred among these are propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 4-methyl-1-hexene and 1-octene, and more preferably 1- Butene and 1-hexene.

The α-olefin content in the linear polyethylene is preferably from 1 mol% to 10 mol%, more preferably from 2 mol% to 5 mol%. If the content of the α-olefin is too small, the flexibility of the fiber is impaired. If the content of the α-olefin is too large, the crystallinity is deteriorated, and the fibers may be fused to each other during fiberization.

The linear polyethylene used in the first component has a density of from 0.90 g/cm ³ to 0.94 g/cm ³ . When the density is less than 0.90 g/cm ³ , the first component becomes soft, and sufficient bulkiness and volume recovery property cannot be obtained as a non-woven fabric, and high-speed combing property is not preferable, and the fabric quality is not good. It is not woven. On the other hand, when the density of the linear polyethylene is more than 0.94 g/cm ³ , the nonwoven fabric will improve the bulkiness and volume recovery property of the nonwoven fabric, but the surface feel of the nonwoven fabric and the flexibility in the thickness direction tend to be deteriorated. Therefore, the linear polyethylene preferably has a density of from 0.90 g/cm ³ to 0.935 g/cm ³ , more preferably from 0.91 g/cm ³ to 0.935 g/cm ³ , still more preferably from 0.913 g. /cm ³ to a density of 0.935 g/cm ³ .

Further, the linear polyethylene preferably has a melting point before spinning of from 110 ° C to 125 ° C. Further, the melting point of the linear polyethylene is preferably higher than the melting point of the added low density polyethylene. If the melting point of the linear polyethylene is too high, it is not treated with low-temperature heat and heat is produced, and then the nonwoven fabric is not obtained, and a non-woven fabric of a practical strength can not be obtained. When the melting point of the linear polyethylene is low, heat treatment is performed at a high temperature to produce heat, and then the nonwoven fabric is not woven, the surface feel of the nonwoven fabric is lowered, or the high-speed combing property is not good, and the fabric quality is not good. Not woven. Linear polyethylene has a higher melting point than added to it The melting point of the low-density polyethylene, whereby the function of the linear polyethylene in the nonwoven fabric is a skeleton polymer, and the low-density polyethylene can also exert the effect as a softening agent, and the fiber or even the fiber assembly obtained therefrom Appropriate softness can be obtained.

The linear polyethylene having the above density and melting point can be easily obtained by copolymerizing ethylene and an α-olefin by using a metallocene catalyst. In particular, as long as it has a density of from 0.90 g/cm ³ to 0.94 g/cm ³ , preferably having the above melting point, the linear polyethylene is not limited to a polymerized using a metallocene catalyst, and may be used, for example. Ziegler-Natta catalysts and agglomerates.

When the spinnability is considered, the melt index (MI) of the linear polyethylene is preferably in the range of 1 g/10 min to 60 g/10 min. Here, the melt index (MI) is measured in accordance with JIS K 7210 (1999) (condition: 190 ° C, load 21.18 N (2.16 kgf)). The larger the MI, the slower the curing speed of the sheath component at the time of spinning, and the fibers are easily fused to each other. On the other hand, if the MI is too small, it is difficult to fibrillate. More specifically, the MI of the linear polyethylene is preferably from 2 g/10 min to 40 g/10 min, more preferably from 3 g/10 min to 35 g/10 min, still more preferably from 5 g/10 min to 30 g/10 min.

The ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) in the linear polyethylene (Q value: Mw/Mn) is preferably 5 or less. More preferably, the Q value is 2 to 4, and more preferably 2.5 to 3.5. When the Q value is 5 or less, the linear polyethylene has a characteristic that the molecular weight distribution width is narrow, and the linear polyethylene satisfying the Q value range is used for the first component, and the composite short fiber excellent in crimping property is obtained. .

Consider the properties of the resulting significantly crimped composite fibers and use significant rolls The touch elasticity and bulkiness of the fiber assembly of the shrinkable composite fiber are preferably in the range of 65 MPa to 850 MPa in the bending elastic modulus of the linear polyethylene. Here, the flexural modulus is measured in accordance with JIS K 7171 (2008). The remarkable crimping composite fiber of the present invention has a soft touch of a linear polyethylene having a main component of the first component, but only a soft and fiber-free elastic force, and the combing passability is lowered, and it is difficult to obtain a fluffy richness. Volume recovery fiber assembly. Therefore, the linear polyethylene is preferably not easily deformed to some extent for bending (i.e., preferably less than a certain degree of deformation for bending), and specifically preferably has a flexural modulus of 65 MPa or more. When the flexural modulus of the linear polyethylene is too large, the soft touch is lost, so it is preferably 850 MPa or less. More specifically, the linear elastic modulus of the linear polyethylene is preferably from 120 MPa to 750 MPa, particularly preferably from 180 MPa to 700 MPa, and most preferably from 250 MPa to 650 MPa.

The hardness of the linear polyethylene is preferably from 45 to 75 in consideration of the properties of the resulting significantly crimped composite fiber and the feel, bulkiness and volume recovery of the fiber assembly using the significantly crimped composite fiber. Within the scope. Here, the hardness of the linear polyethylene is based on JIS K 7215 (1986), and refers to a hardness meter hardness (HDD) measured using a D-type durometer. If the linear polyethylene of the main component of the first component is too soft, the elastic force of the fiber is lost, and the combability of the fiber is reduced, so that it is difficult to obtain a fluffy fiber assembly, and the volume recovery of the fiber assembly is also reduce. Therefore, the linear polyethylene preferably has a certain degree of hardness, specifically, a hardness of 45 or more. If the hardness of the linear polyethylene is too large, the soft touch is lost, so it is preferably 75 or less. More specific The linear polyethylene preferably has a hardness of 48 to 70, particularly preferably 50 to 65, and most preferably 50 to 62.

The low-density polyethylene (also referred to as "LDPE") contained in the first component is a soft polyethylene having a large difference, and is also called a high-pressure polyethylene because of its production method. In the present invention, by adding a small amount of low-density polyethylene to the first component, the remarkable crimping is more satisfactorily exhibited, and the bulkiness and volume recovery property of the nonwoven fabric and the high-speed carding property can be improved. Further, since the low-density polyethylene is softer than the linear polyethylene, for example, the surface touch which is lowered when a linear polyethylene having a high density is used can be secured by low-density polyethylene.

The density of the low density polyethylene is preferably from 0.91 g/cm ³ to 0.93 g/cm ³ . The density of the low-density polyethylene tends to depend on the MI (190 ° C) of the polymer. Therefore, in consideration of the spinnability, the density of the low-density polyethylene is preferably from 0.915 g/cm ³ to 0.92 g/cm ³ .

The melting point of the low density polyethylene is preferably from 90 ° C to 120 ° C. In the present invention, it is preferred to use a low-density low-density polyethylene. By using a low-density polyethylene having a low melting point, significant curling can be performed more satisfactorily, and a field of hot working temperature in the production of a nonwoven fabric can be made wider, and a soft nonwoven fabric can be obtained after the heat treatment. More specifically, the melting point of the low density polyethylene is preferably from 95 ° C to 115 ° C, particularly preferably from 100 ° C to 110 ° C. Further, the melting point of the low-density polyethylene is preferably lower than the melting point of the aforementioned linear polyethylene. The melting point of the low-density polyethylene is more preferably 5 ° C or more lower than the melting point of the linear polyethylene, and more preferably 10 ° C or more lower than the melting point of the linear polyethylene.

If the spinning property is considered, the melting index (MI) of the low density polyethylene is generally It is preferably in the range of from 1 g/10 min to 60 g/10 min. Here, the melt index (MI) is measured in accordance with JIS K 7210 (1999) (condition: 190 ° C, load 21.18 N (2.16 kgf)). The larger the MI, the slower the curing speed of the sheath component at the time of spinning, and the fibers are easily fused to each other. On the other hand, if the MI is too small, it is difficult to fibrillate. More specifically, the MI of the low density polyethylene is preferably from 3 g/10 min to 50 g/10 min, more preferably from 5 g/10 min to 50 g/10 min, still more preferably from 10 g/10 min to 50 g/10 min.

The Q value in the low density polyethylene is preferably 10 or less. A more preferable Q value is 4 to 9, and more preferably 5 to 8. When the Q value exceeds 10, a good crimping expression shape cannot be obtained, and the strength tends to decrease.

In the first component, when the total mass of the linear polyethylene and the low-density polyethylene is 100% by mass, it is preferably 95% by mass to 75% by mass of the linear polyethylene and 55% by the low-density polyethylene. Mix in a mass % to 25% by mass. More preferably, the linear polyethylene accounts for 90% by mass to 80% by mass, and the low-density polyethylene accounts for 10% by mass to 20% by mass. When the proportion of the linear polyethylene is too large, it is difficult to obtain the effect of adding the low-density polyethylene, and when it is not woven, the bulkiness of the nonwoven fabric is also deteriorated. If the proportion of the linear polyethylene is too small, a non-woven fabric having high strength cannot be obtained as a heat non-woven fabric.

When the low-density polyethylene contained is in the above range, the three-dimensional crimping is excellent in the composite short fibers, and the inconsistency in the crimping is small, and the crimp ratio of the fibers is increased. Therefore, the nonwoven fabric containing the fiber has good bulkiness. The reason for the easy expression of the three-dimensional crimp is not certain, but it is presumed that it is due to the low-density polyethylene in the linear polyethylene with less difference. The long difference and extension are easy to cause deformation, so it is easy to express the three-dimensional crimp. In particular, the invention is not limited to this speculation. Further, since the low-density polyethylene has a function as a softening agent, when a low-density polyethylene having the above-described range is used, for example, when a linear polyethylene having a high density is used, the obtained nonwoven fabric exhibits excellent flexibility in the thickness direction, and The surface feels better. In addition, when the low-density polyethylene of the above range is contained, the processing temperature range of the nonwoven fabric can be broadened, and when the heat of production is not woven, the processing temperature is not limited, and a non-woven fabric having a soft touch that is almost fixed can be obtained.

As long as the composite short fibers exhibit a sufficiently three-dimensional crimp and are a non-woven fabric having a good touch, the first component may contain other polymer components other than linear polyethylene and low density polyethylene. For example, the first component may contain high density polyethylene, polypropylene, polybutene, polybutylene, polymethylpentene resin, polybutadiene, propylene copolymer (eg propylene-ethylene) Copolymer), ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, or ethylene-methyl (meth) acrylate copolymer, etc., polyolefin resin, poly pair Ethylene phthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene succinate Polyester resin such as polyester resin such as copolymer and copolymer thereof, nylon 66, nylon 12, and nylon 6, acrylic resin, polycarbonate, polyacetal, polystyrene, cyclic polyolefin, etc. One or more polymer components selected from engineering plastics, such mixtures, and such elastomeric resins.

The polymer component of the first component is preferably a linear polyethylene with a low density The total mass of the polyethylene added is 50% by mass or more, more preferably 75% by mass or more, and even more preferably only contains the polymer component.

The first component may contain components other than the polymer component, for example, an antistatic agent, a pigment, a matting agent, a heat stabilizer, a light stabilizer, a flame retardant, an antibacterial agent, a slip agent, a plasticizer, a softener, and an anti-static agent. Additives such as oxidizing agents, ultraviolet absorbers, and crystal nucleating agents. Such an additive is preferably contained in the first component in an amount of 10% by mass or less based on the entire first component.

The polymer component of the second component is a polyester having a melting point of 50% by mass or more higher than the melting point of the linear polyethylene constituting the first component. The polymer component of the second component preferably contains 50% by mass or more of the polyester, more preferably 75% by mass or more, and most preferably 100% by mass.

Polyester is cheaper and has higher rigidity than other polymers, and is suitable for use because it imparts fiber elasticity. The polyester may, for example, be a polymer or copolymer of polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate or polylactic acid. The melting point of the polyester is higher than the melting point of the linear polyethylene constituting the first component by 40 ° C or more. Preferably, the melting point temperature of the polyester is higher than the melting point of the linear polyethylene by 50 ° C or more.

Among the above polyesters, polyethylene terephthalate and polybutylene terephthalate are highly rigid and impart elasticity to the fiber compared to polytrimethylene terephthalate, so that significant curling property is obtained. The composite short fibers have good high-speed combing properties. In particular, polyethylene terephthalate is most suitable for use because of its rigidity. Polyethylene terephthalate can additionally have high crystallinity by appropriately adjusting the elongation conditions in fiber production, and becomes difficult to heat shrink, so that significant curling which does not show or only shows some micro-potential crimpability can be obtained. Composite short fibers. If When a non-woven fabric made of such a remarkably crimped composite short fiber is used, when the web is heat-treated, no or only slight shrinkage occurs in the web, which may remove or alleviate the trouble of manufacturing engineering management due to web shrinkage.

When the second component is suitable for polyester containing polyethylene terephthalate and/or polybutylene terephthalate, and other polymer components, the other polymer component is only in the composite short fiber. There is no particular limitation on the display of a sufficient three-dimensional crimp and imparting a good touch to the fiber. For example, other polyester resins, specifically, polyethylene naphthalate, polylactic acid, and polytrimethylene terephthalate may be mixed. However, since the polytrimethylene terephthalate is soft as described above, the high-speed carding property of the obtained fiber tends to be lowered, so that it is preferably not used in the remarkably crimped composite short fiber of the present invention.

The second component may contain components other than the polymer component, such as antistatic agents, pigments, matting agents, thermal stabilizers, light stabilizers, flame retardants, antibacterial agents, slip agents, plasticizers, softeners, antioxidants. Additives such as UV absorbers and crystal nucleating agents. The amount of such an additive is preferably contained in the second component in an amount of 10% by mass or less based on the entire second component.

In the remarkably crimped composite staple fiber of the present invention, (second component/first component) is preferably from 8/2 to 3/7 (volume ratio). More preferably from 7/3 to 35/65, most preferably from 6/4 to 4/6. When the nonwoven fabric is produced from the remarkably crimped fiber of the present invention, the second component mainly imparts bulkiness and volume recovery property to the nonwoven fabric, and the first component mainly imparts strength to the nonwoven fabric and softness of the nonwoven fabric. If the composite ratio is 8/2 to 3/7, the non-woven strength, softness, and volume recovery can be achieved at the same time. If the composite ratio is too large, the non-woven fabric strength will increase, but the resulting non-woven fabric will become hard and the volume recovery tends to deteriorate. On the other hand, when the number of the second component is too large, the dot becomes too small, and the strength of the nonwoven fabric is reduced, so that the volume recovery property tends to be deteriorated.

In the significant crimping recombination of the present invention, the position of the center of gravity of the second component is offset from the position of the center of gravity of the fibers in the cross section of the fiber. Fig. 1 is a view showing a fiber cross section of a composite short fiber in an embodiment of the present invention. The first component (1) is disposed around the second component (2), and the first component (1) accounts for at least 20% of the surface of the fiber (10) in the fiber cross section. Thereby, the surface of the first component (1) is melted upon heat. In the fiber cross section, the position (3) of the center of gravity of the second component (2) deviates from the position of the center of gravity (4) of the fiber (10), and the ratio of the deviation (hereinafter referred to as eccentricity) means that the fiber cross section of the composite short fiber is Enlarged photographing by an electron microscope, etc., and the position (3) of the center of gravity of the second component (2) in the fiber cross section is taken as C1, and the position (4) of the center of gravity of the fiber in the fiber cross section of the significantly crimped composite fiber (10) is taken as Cf, When the radius (5) of the fiber cross section of the significantly crimpable composite fiber (10) is taken as rf, the numerical value of the following formula is used.

Eccentricity (%) = [| Cf-C1 | / rf] × 100

The position of the center of gravity of the second component (2) (3) is a fiber cross-section which deviates from the position of the center of gravity of the fiber (4). The preferred form is an eccentric core sheath type as shown in Fig. 1, or a side-by-side type. Depending on the situation, it may also be present in a multi-core type that is collected in a multi-core portion and deviated from the center of gravity of the fiber. In particular, if the cross section of the eccentric core-sheath type fiber is easily expressed as a wave-shaped crimp and/or a spiral crimp, it is preferable from the viewpoint. The eccentricity of the eccentric core-sheath type composite short fibers is preferably from 5% to 50%. A better eccentricity is 7% to 30%. In addition, the shape of the fiber cross section of the second component may be elliptical, Y-shaped, X-shaped, well-shaped, polygonal, star-shaped or the like in addition to a circular shape, and the composite shape is short. The shape of the fiber cross section of the fiber (10) may be other shapes such as an ellipse, a Y shape, an X shape, a well shape, a polygon shape, a star shape, or the like, in addition to a circular shape.

Fig. 2 is a view showing a crimped form of a remarkably crimped composite short fiber in an embodiment of the present invention. The wave-shaped crimping system according to the present invention means that the crimped portion is curved as shown in Fig. 2A. The spiral crimping indicates that the rolled portion is a spiral bend as shown in Fig. 2B. The crimping in which the wave-shaped crimping and the spiral crimping are mixed as shown in Fig. 2C is also included in the present invention. If the mechanical winding is normal as shown in Fig. 3, the rolled roll is an acute angle, that is, it is directly zigzag-shaped, and the volume recovery property cannot be increased as a non-woven fabric. Furthermore, the elasticity of the surface to be compressed, that is, the spring effect is not good, and in particular, sufficient volume recovery is not obtained. Further, if it is a crimp of an acute angle of mechanical crimping as shown in Fig. 4, the crimping in which the wave shape shown in Fig. 2A is mixed is also included in the present invention. The present invention includes a wave-shaped crimp and a helical crimp, and is distinguished from a mechanical crimp as a three-dimensional crimp.

In the present invention, in particular, the crimping in which the wave-shaped crimping and the spiral crimping are mixed as shown in Fig. 2C is preferable from the viewpoint that the combing passability and the initial volume and volume recovery property can be simultaneously achieved.

The significantly crimpable composite staple fibers of the present invention can be produced in the following order. First, a first component containing a linear polyethylene and a low-density polyethylene, and a second component containing, for example, 50% by mass or more of polyethylene terephthalate and/or polybutylene terephthalate, Arranging the first component in the fiber cross section at least 20% of the surface of the fiber, and the position of the center of gravity of the second component is offset from the center of gravity of the fiber, and using a composite nozzle, such as an eccentric core-sheath composite nozzle, the second component Spinning temperature 240 ° C to 330 ° C, the first The parts were melt-spun at a spinning temperature of 200 ° C to 300 ° C, and were drawn at a drawing speed of 100 m / min to 1500 m / min to obtain a spun filament.

Next, the glass transition point (Tg ₂ ) of the polymer component having the highest glass transition point among the polymer components contained in the second component is not higher than the extension temperature of the peak temperature of the linear polyethylene. The elongation treatment was carried out at a stretching ratio of 1.8 times or more. A more preferred lower limit of the extension temperature is a temperature 10 ° C higher than Tg ₂ . More preferably, the upper limit of the extension temperature is 95 ° C, and particularly preferably, the upper limit of the extension temperature is 90 ° C. When the elongation temperature is lower than Tg ₂ , the crystallization of the second component is difficult to proceed, so that the heat shrinkage of the second component in the obtained fiber is increased, and the non-woven fabric made of the obtained fiber tends to have a small volume recovery property. . If the stretching temperature is higher than the melting peak temperature of the linear polyethylene, the fibers are fused to each other, which is not preferable.

A better lower limit of the stretching ratio is 2 times, and a particularly preferable lower limit of the stretching ratio is 2.2 times, and the lower limit of the optimum stretching ratio is 2.4 times. The upper limit of the stretch ratio is 5 times, the upper limit of the stretch ratio is 4.0 times, and the upper limit of the best stretch ratio is 3.5 times. When the stretching ratio is less than 1.8 times, it is difficult to obtain a fiber which exhibits a wave shape curling and/or a spiral crimping because the stretching ratio is low, and as the nonwoven fabric, not only the bulkiness is small but the rigidity of the fiber itself is also small. The non-woven fabric of the carding passability or the like has poor manufacturability, or the volume recovery property tends to be lowered. Further, it is necessary to perform an annealing treatment in an atmosphere of dry heat, moist heat, steaming or the like at a temperature at which the fibers of 50 ° C to 115 ° C are not melted at the time of stretching.

Next, it is necessary to use a known crimping machine such as a stuffing box type crimping machine before or after the fiber treating agent is given, and to give the number of crimps. 5 peaks / 25mm to 25 peaks / 25mm curling. The crimped shape after passing through the crimping machine can be a zigzag crimp and/or a wave shape crimp. If the number of crimps is less than 5 peaks/25 mm, the carding passability is lowered, and the bulkiness and volume recovery of the nonwoven fabric tend to deteriorate. On the other hand, when the number of crimps exceeds 25 peaks/25 mm, the carding passability is lowered due to the excessive number of crimps, and not only the fabric of the nonwoven fabric is deteriorated, but also the initial volume of the nonwoven fabric is also reduced.

Further, it is preferred to carry out an annealing treatment in a dry heat, a moist heat, or a steaming atmosphere at 50 ° C to 115 ° C after the crimping machine is crimped. The three-dimensional crimping exhibited in the significantly crimpable composite short fibers can be promoted by the annealing treatment. Specifically, it is preferred that the fiber treatment agent is applied to the crimping machine to be crimped, and the annealing treatment is carried out in a dry heat atmosphere of from 50 ° C to 115 ° C, and the drying treatment can be carried out to simplify the steps. When the annealing treatment is less than 50 ° C, the dry heat shrinkage ratio of the obtained fiber tends to increase, and the resulting nonwoven fabric is disordered in productivity and productivity is lowered. Further, when the annealing process is performed simultaneously with the drying process, if the annealing temperature is less than 50 ° C, the drying of the fiber may be insufficient. By such a method, a substantially crimped composite short fiber exhibiting a three-dimensional crimp can be obtained.

In the significantly crimped composite short fiber of the present invention thus obtained, the number of crimps (the number of crimps) is preferably 12 peaks/25 mm to 18 in consideration of the combing property of the fibers and the bulkiness as a nonwoven fabric or the like. Peak / 25mm. Further, when the number of crimps and the crimp ratio of the significantly crimpable composite short fibers of the present invention are measured in accordance with JIS L 1015 (2010), the ratio of the crimp ratio to the number of crimps (volume ratio/crimpage) The number is preferably from 0.7 to 1.2, more preferably from 0.85 to 1. The crimp ratio indicates the fixation of the crimp (the difficulty of curling elongation), and if the crimp ratio/volume number is satisfied In the above range, since the crimping is difficult to elongate and has a moderately sized waveform and/or a spiral crimp, the combing property is good, the bulkiness after the carding is maintained, and the nonwoven fabric after the heat treatment can maintain elasticity.

The fineness and fiber length of the significantly crimpable composite short fibers of the present invention are not particularly limited and are selected depending on the use. For example, the remarkably crimped composite short fiber of the present invention is prepared by a carding machine (or other means), and then the fibers are thermally bonded to each other to produce heat and then non-woven fabric. In this case, the fineness is preferably used. From 1.1 dtex to 15 dtex, the fiber length is preferably from 1 mm to 100 mm. For example, when the remarkable crimped composite staple fiber of the present invention is used as a surface material of a sanitary material, the fineness thereof is preferably from 1.5 dtex to 3.5 dtex. These deniers and fiber lengths can be used in the manufacture of non-woven fabrics other than non-woven fabrics, and there is no need to mention them. Specifically, the significantly crimped composite staple fiber of the present invention has a dry nonwoven fabric (for example, an air-through nonwoven fabric, a spunlace nonwoven fabric, and a needle punch) which are suitably used for fabricating a fiber web by a carding machine. (needle punch) non-woven fabric, etc.) (long fiber length (fiber length 15mm to 80mm, more preferably 32mm to 64mm), suitable for producing wet non-woven fabric fiber length (fiber length 1mm to 20mm, more preferably 3mm to 15mm), Or it may have a fiber length (1 mm to 30 mm, more preferably 5 mm to 25 mm) suitable for producing an air-laid nonwoven fabric. The fineness can be adjusted in a desired manner by adjusting the fineness and the stretching ratio of the spun filament. The fiber of a predetermined length is obtained by cutting the fiber after the aforementioned annealing treatment.

The fiber assembly contains 20% by mass or more of the significantly crimpable composite short fibers of the present invention described above, whereby the surface feel is good and fluffy. A fiber assembly excellent in flexibility, thickness direction, and volume recovery. The fiber assembly may be a woven fabric or a non-woven fabric.

Next, a non-woven fabric of a specific example of the fiber assembly of the present invention and a method for producing the same will be described. The fiber web is produced in such a manner that the substantially crimpable composite short fibers are contained in an amount of 20% by mass or more, and then the fibers are integrated with each other by a method such as entanglement fibers and/or heat bonding, thereby obtaining a nonwoven fabric. When other fibers are used, the other fibers may be, for example, natural fibers such as cotton, silk, wool, hemp, pulp, recycled fibers such as sputum, cuprammonium, and acrylic, polyester, and polyamide. One or a plurality of types of fibers are selected from synthetic fibers such as a polyolefin, a polyolefin, and a polyurethane. The other fibers may be used in combination with the significantly crimpable composite short fibers of the present invention or with the fibrous web laminate formed by the significantly crimped composite short fibers of the present invention.

The fiber web used in the manufacture of the aforementioned non-woven fabrics may be, for example, a parallel net, a semi-random net, a random net, a staggered net, and a cross-stitched web, a carded web, an air-laid net, a wet paper net, and a spunbond ( Spunbond) network. Two or more different types of fiber webs can be laminated.

When the nonwoven fabric is produced by using the remarkably crimped composite short fibers of the present invention, it is preferred to carry out heat treatment on the fiber web, and to obtain a non-woven fabric in a form in which the fibers are thermally followed by the first component and then the nonwoven fabric is not woven. The heat and the non-woven fabric remarkably exert the effects (softness in the thickness direction, volume recovery property, and volume recovery property) brought about by the remarkable crimped composite short fibers of the present invention. In order to complex the fibers, the fiber web may be subjected to a needle punching treatment and a water flow entanglement treatment before and/or after the heat treatment.

In order to obtain heat followed by non-woven fabric, heat treatment is performed on the aforementioned fiber web by a known heat treatment means. The heat treatment means is preferably a heat treatment machine in which a pressure such as a hot air through heat treatment machine, a hot air blowing type heat treatment machine, or an infrared heat treatment machine is less likely to be applied to the fiber web. The heat treatment conditions such as the heat treatment temperature are selected to sufficiently melt and/or soften the first component and the fibers are joined to each other at the joint or the intersection, and the three-dimensional crimping of the significantly crimped composite short fiber is not crushed. . For example, when the melting peak temperature before spinning of the linear polyethylene (the melting peak temperature of the linear polyethylene having the highest melting peak temperature when the plurality of linear polyethylenes are contained in the first component) is taken as Tm The heat treatment temperature is preferably a temperature of from Tm ° C to (Tm + 40) ° C. A more preferable heat treatment temperature range is (Tm + 5) ° C to (Tm + 30) ° C.

The heat thus produced is followed by a non-woven fabric having a good surface feel and high bulkiness and volume recovery. Further, the thermal adhesive non-woven fabric exhibits high flexibility in the thickness direction of the non-woven fabric. The softness in the thickness direction of the non-woven fabric can be expressed as a "compressed volume" index. When the non-woven fabric of the same thickness is used, the non-woven fabric is "easy to compress" in the thickness direction and is soft when the volume is smaller after compression. The softness in the thickness direction of the non-woven fabric can be expressed as an indicator of the "volume change rate". For the original nonwoven fabric volume (thickness), the volume change rate is expressed by the ratio of the volume change (thickness) of the compression, and the larger the volume change rate, the softer the nonwoven fabric is in the thickness direction. The heat change rate of the non-woven fabric containing the remarkable crimped composite short fibers of the present invention is preferably 85% or more. More preferably, it is 88% or more.

Further, the heat and then the nonwoven fabric can be evaluated by the volume recovery (compression after compression) after compression in the thickness direction. Compressed recovery volume table It shows the volume recovery in the thickness direction of the non-woven fabric, and the larger the recovery volume, the more cushioning (elasticity). When the shock-absorbing non-woven fabric is used as a surface material for sanitary articles, it moves along with the body and enhances the adhesion to the skin. The volume recovery after compression is expressed as the ratio of the non-woven volume (thickness) after removing the load from the compressed state and after a certain period of time, relative to the volume (thickness) of the non-woven fabric before compression, and the larger the volume recovery after compression, the larger the shock absorption. Sex. The heat recovery ratio of the non-woven fabric containing the remarkable crimped composite short fibers of the present invention is preferably 60% or more. More preferably, it is 65% or more, and particularly preferably 68% or more.

Heat, non-woven fabric surface feel and thickness direction softness, bulkiness, volume recovery (elasticity) is one of the objective evaluation methods for measuring cloth touch, which can be measured and/or evaluated according to KES (Kawabata Evaluation System). . The surface feel of the heat-non-woven fabric can be evaluated by measuring the surface friction characteristic value defined by KES, and the softness, bulkiness, and volume recovery (elasticity) of the thickness of the non-woven fabric can be measured by the compression defined by KES. The load-displacement curve at the time of the test was evaluated by moving the obtained compression characteristic value. Specifically, the characteristic value of the surface friction is a change in the average friction coefficient (hereinafter referred to as MIU) and the average friction coefficient (also referred to as a friction coefficient μ average deviation, hereinafter referred to as MMD). The MIU indicates the difficulty of sliding the surface (or the ease of sliding), and the larger the MIU indicates that it is difficult to slide. MMD indicates the inconsistency of friction, and the larger the MMD, the rough surface. The surface containing the heat of the significantly crimped composite short fibers of the present invention, which is not woven, has a tendency to have a high MIU but a small MMD. Touching such a non-woven fabric with your hand will have a sense of resistance, but at the same time there will be a sense of smoothness, so there will be a unique meaning called "smoothness" and "wetness". Touch. The apparatus for measuring the characteristic value of the surface friction is not particularly limited as long as it is a surface friction measurement based on KES. The characteristic value of the surface friction can be measured, for example, by using a KES-SE friction feeling tester, a KES-FB4-AUTO-A automated surface tester (all manufactured by Keskato Co., Ltd.), or the like.

The compression characteristic value is a compression hardness (also referred to as linearity of compression characteristics, hereinafter referred to as LC), compression energy (also referred to as compression work amount, hereinafter referred to as WC (gf.cm/cm ² )), and compression elasticity. Resilence (also known as compression recovery, compression recovery rate, hereinafter referred to as RC (%)), T ₀ (thickness (mm) when the load is 0.5 gf/cm ² ), Tm (load weight is 50 gf / The thickness (mm) of cm ² and the compression ratio (determined by the above formula T ₀ and Tm and 100 × (T ₀ -Tm) / T ₀ . Hereinafter referred to as EMC (%)). LC indicates compressibility with a small force, and the larger the LC, the harder the compression. WC represents the amount of work of compression, and the larger the WC, the softer the thickness direction and the easier it is to compress. RC indicates the elasticity (recovery, resilience) for compression, and the larger the RC, the easier it is to rebound, that is, the shock absorption. EMC indicates the ratio of the thickness change when two types of loads are applied, and the larger the EMC, the softer and more fluffy, and the larger the deformation when the load is applied. The heat-non-woven fabric containing the remarkably crimped composite short fibers of the present invention is not only bulky and bulky at first because of its large compression ratio, but also has a small compression strength and a large compression energy, so that the thickness direction is easily compressed and soft. The heat containing the remarkable crimped composite short fibers of the present invention, followed by the nonwoven fabric, is additionally excellent in the elasticity of compression, so that it exhibits good shock absorbing properties against the elasticity of compression. The apparatus for measuring the compression characteristic value obtained by shifting the load-displacement curve at the time of the compression test is not particularly limited as long as the compression characteristic value is measured based on KES. The compression characteristic value can be measured, for example, by using a KES-G5 HANDY compression tester or a KES-FB3-AUTO-A automated compression tester (all manufactured by Keskato Co., Ltd.).

The surface characteristics, that is, the surface friction of the non-woven fabric after the heat is applied, the surface on which the hot air is blown in the nonwoven fabric is measured, the longitudinal direction is the measurement direction (also referred to as the MD direction), the static load is 25 gf, and the moving speed of the friction is Measured at 1 mm/sec. The compression characteristic, that is, the compression characteristic of the heat-non-woven fabric compression test, which is obtained by the movement of the load-displacement curve, is a circular surface in which the surface of the non-woven fabric is blown with hot air as a measuring surface and the area of use is 2 cm ² . The press plate was measured by a compressor having a speed of 0.02 cm/sec, an upper limit load of 50 gf/cm ² and a DEF sensitivity of 20.

The heat-containing non-woven fabric containing the remarkable crimped composite short fibers of the present invention is characterized by smooth and soft touch. In order to feel smooth and soft when touching the same, it is important to vary the mean friction coefficient (MIU) and the average friction coefficient (MMD) in the characteristic values of the surface friction of the aforementioned KES. In the heat-non-woven fabric containing the remarkable crimped composite short fibers of the present invention, the average friction coefficient MIU of the surface of the heat-non-woven fabric is preferably 0.3 or more and 0.6 or less. The average friction coefficient is 0.3 or more, that is, the friction is larger than the conventional non-woven fabric, so that when the heat is not contacted with the non-woven fabric, the heat and the non-woven fabric and the skin will have moderate friction and resistance, and the feeling of the touch is "smoothness". And "wet feeling". When the average friction coefficient is 0.6 or less, the average friction coefficient of the heat and the non-woven fabric is not excessively large, and the touch is deteriorated (for example, the feeling of sticking to the skin and the feeling of touch are caused by excessive friction). The average coefficient of friction (MIU) is preferably 0.3 or more and 0.5 or less, and particularly preferably 0.32. Above 0.45 or less. Next, the change in the average coefficient of friction (MMD) of the surface of the non-woven fabric containing the heat of the remarkably composite short fibers of the present invention is preferably 0.016 or less. The variation of the average friction coefficient is 0.016 or less, whereby the non-woven surface is not rough, and if the average friction coefficient MIU satisfies the above range, the two are added together so that the touch of the heat and the non-woven fabric has a smooth and soft unique "smoothness". 』. The variation of the average friction coefficient is preferably 0.015 or less. The lower limit of the variation of the average friction coefficient (MMD) is not particularly limited, and the closer to 0, the better, but it may be 0.001 or more.

The heat containing the remarkable crimped composite short fibers of the present invention is not woven, and is not only initially bulky, but also soft and easy to compress when a load is applied. Then, if the load is removed or the load becomes small, there is a characteristic that the volume of the thermal non-woven fabric rebounds quickly. In order to show the characteristics of these compressions and compression liberation, it is important to use LC, WC, RC, EMC in the aforementioned KES compression characteristic values. In the heat-non-woven fabric containing the remarkable crimped composite short fibers of the present invention, the compression hardness (LC) is preferably 0.64 or less. By compressing the hardness to 0.64 or less, it is possible to obtain a soft touch without being excessively hard during compression. The compression hardness (LC) is preferably 0.62 or less, and particularly preferably 0.6 or less. The lower limit of the compression hardness (LC) is not particularly limited, but may be 0.15 or 0.2. Further, the compression hardness (LC) is affected by the density (g/m ² ) of the non-woven fabric to be measured, and the compression hardness is also increased as the density of the non-woven fabric is increased. Therefore, the value of the compression hardness (LC) divided by the value of the density, that is, the compression hardness per unit density (g/m ² ) (LC) can be used as the compression characteristic value of the thermal adhesive nonwoven fabric. In the heat-bonded nonwoven fabric containing the remarkable crimped composite short fibers of the present invention, the compression hardness (LC) per unit density (g/m ² ) is preferably 0.013 or less, more preferably 0.012 or less.

In the heat-bonded nonwoven fabric containing the remarkable crimped composite staple fiber of the present invention, the compression energy (WC) is preferably 1.0 gf. Cm/cm ² or more. The compression energy (WC) is at 1.0gf. In the case of cm/cm ² or more, the nonwoven fabric is deformed greatly when the load is applied, and the soft feeling is increased. The compression energy (WC) is preferably 2.5gf. Cm / cm ² or more, particularly preferably 4.5gf. Cm / cm ² or more, the best is 5.1gf. Cm/cm ² or more. The upper limit of the compression energy is not particularly limited, but is greater than 8.0 gf. Cm/cm ² may affect other compression characteristics, so it is preferably 8.0gf. Cm/cm ² or less, more preferably 6.0 gf. Cm/cm ² or less.

In the heat-bonded nonwoven fabric containing the remarkable crimped composite short fibers of the present invention, the compressive elastic energy (RC) is preferably 58% or more. By compressing the elastic energy to be 58% or more, the heat and the non-woven fabric are excellent in resilience, and the volume is not woven with the recovery when the load is reduced or the load is removed. In particular, by making the aforementioned compression hardness (LC) satisfy the preferred range and the compressive elastic energy (RC) satisfies the preferred range, the nonwoven fabric is softened for the deformation of the compression, and the original volume (i.e., the original shape) is restored when the load is reduced. Therefore, the heat is followed by the non-woven fabric which is easy to change with the uneven portion of the body. If the non-woven fabric is used for the surface material of various sanitary materials, the surface material will compress/recover with the change of the body movement and posture, thus having Easy to keep in touch with the body and gain the comfort. The upper limit of the compressive elastic energy (RC) is not particularly limited and may be 100%, 90% or 85%.

In the heat-non-woven fabric containing the remarkable crimped composite short fibers of the present invention, the compression ratio (EMC) is preferably from 70% to 98%. The compression ratio refers to the use of the load of a thickness of ^2:00 0.5gf / cm is T _0, the load of the thickness of ^2:00 50gf / cm of Tm, and to EMC (%) = 100 × ( T 0 -Tm) / T ₀ The compression characteristic value sought. When the compression ratio is less than 70%, it is not only initially small in size but also hardly deformed for compression, and when heat is applied to the nonwoven fabric, the ratio of deformation can be small as the load increases, and the touch becomes hard. When the compression ratio is more than 98%, the deformation at the time of applying the load is excessively large, so that the shape maintenance property is likely to be lowered, and even if the load is small, the heat is crushed and then the nonwoven fabric is not formed to have a flat sheet shape. The compression ratio (EMC) is preferably from 72% to 95%, particularly preferably from 75% to 90%, most preferably from 78% to 85%, in the heat of the non-woven fabric using the remarkable crimped composite short fibers of the present invention.

The fiber assembly of the present invention, especially the non-woven fabric, more particularly the non-woven fabric, has a good surface feel and softness and shock absorption, so it is suitable for the surface material of sanitary articles such as sanitary napkins and disposable diapers, and wet tissues. , wipes, cosmetics materials, women's underwear pads, shoulder pads, vehicle shock absorbers, floor heating floor materials, cushioning materials, and packaging materials.

The heat of the present invention is not particularly suitable for the surface material of sanitary articles, and the present invention additionally provides a sanitary article using the heat of the present invention as a surface material. A sanitary article is a product containing an absorbent body such as blood, body fluid, and excrement discharged from a human or an animal, and is a product such as a disposable diaper, a sanitary napkin, and a leaking pad, which is also called an absorbent article. The surface materials of these products are directly adhered to the delicate parts of the human body or animals, so that not only the surface feel but also the flexibility and shock absorption in the thickness direction are required to have excellent characteristics. The heat-resistant non-woven fabric of the present invention is excellent in surface feel, flexibility, and volume recovery as described above, and is therefore suitable as a surface material. Other components simultaneously constitute a sanitary article.

When the heat of the present invention is subsequently used as a surface material for a sanitary article, the density thereof is preferably from 10 g/m ² to 70 g/m ² , more preferably from 15 g/m ² to 60 g/m ² . In particular, the density may be outside of these ranges depending on the type of sanitary article. Further, when the heat of the present invention is used for other purposes, the density is appropriately selected depending on the use.

When the heat-resistant nonwoven fabric of the present invention is used as a surface material for a sanitary article, it is preferably contained in an amount of 20% by mass or more of the above-mentioned remarkably crimped composite short fibers, more preferably 50% by mass or more, particularly preferably 80% by mass or more. . When the ratio of the above-mentioned remarkably crimped composite short fibers is within the above range, it is excellent not only as the surface feel of the surface material but also in the thickness direction and the shock absorbing property, and can exhibit the function of preventing the surface material such as dry skin. .

(Example) [Examples 1 to 13, Comparative Examples 1 to 6] (first ingredient)

The following linear polyethylene (LLDPE), low density polyethylene (LDPE), and high density polyethylene (HDPE) were prepared.

LLDPE-1: a linear polyethylene polymerized by a metallocene catalyst (manufactured by Ube Maruzen Polyethylene Co., Ltd., trade name "420SD", density: 0.918 g/cm ³ , Q value of 3.0, MI = 7 g/10 min, melting point 118 ° C, hexene copolymerization, bending modulus of elasticity 280 MPa, hardness (HDD) 52).

LLDPE-2: a linear polyethylene polymerized by a metallocene catalyst (manufactured by Ube Maruzen Polyethylene Co., Ltd., trade name "UMERIT (registered trademark) 631J", density 0.931 g/cm ³ , Q value 3.0, MI = 20 g/10 min, melting point 120 ° C, hexene copolymerization, bending elastic modulus 600 MPa, hardness (HDD) 60).

LLDPE-3: a linear polyethylene polymerized by a metallocene catalyst (manufactured by The Dow Chemical Co., Ltd., trade name "ASPUN (registered trademark) 6835A", density: 0.950 g/cm ³ , Q value of 3.5, MI = 17 g/10 min , melting point 126 ° C, octene copolymerization).

LLDPE-4: a linear polyethylene polymerized by a metallocene catalyst (manufactured by Nippon Polyethylene Co., Ltd., trade name "KERNEL (registered trademark) KS560T", density 0.898 g/cm ³ , Q value 3.1, MI = 16 g /10 min, melting point 86 ° C, hexene copolymerization, flexural modulus 62 MPa, hardness (HDD) 40).

LLDPE-5: Linear polyethylene polymerized by Ziegler-Natta catalyst (manufactured by Nippon Polyethylene Co., Ltd., trade name "NOVATEC (registered trademark) UJ370T", density 0.921 g/cm ³ , Q value 4.2 , MI = 22 g/10 min, melting point 121 ° C, hexene copolymerization, bending modulus of elasticity 180 MPa, hardness (HDD) 50).

LDPE-1: manufactured by Nippon Polyethylene Co., Ltd., trade name "NOVATEC (registered trademark) LJ802", density 0.918 g/cm ³ , Q value 5.3, MI = 22 g/10 min, melting point 106 °C.

LDPE-2: "NOVATEC (registered trademark) LJ902", manufactured by Nippon Polyethylene Co., Ltd., density: 0.915 g/cm ³ , Q value 5.3, MI = 45 g/10 min, melting point 102 °C.

LDPE-3: "NOVATEC (registered trademark) LC720", manufactured by Nippon Polyethylene Co., Ltd., density: 0.922 g/cm ³ , Q value 5.1, MI = 9.4 g/10 min, melting point 110 °C.

LDPE-4: manufactured by Ube Maruzen Polyethylene Co., Ltd., trade name "J2516", density 0.916 g/cm ³ , MI = 25 g/10 min, melting point 106 °C.

LDPE-5: manufactured by Ube Maruzen Polyethylene Co., Ltd., trade name "J3519", density 0.916g/cm ³ , MI=35g/10min, melting point 108°C

HDPE: manufactured by Nippon Polyethylene Co., Ltd., trade name "NOVATEC (registered trademark) HE481", density 0.956g/cm ³ , Q value 5.6, MI=12g/10min, melting point 133°C, flexural modulus 900MPa, hardness (HDD) ) 64.

(second component)

Polyethylene terephthalate (manufactured by Toray Co., Ltd., trade name "T200E", melting point 250 ° C, ultimate viscosity value (IV value) 0.64) was prepared as a polymer constituting the second component.

The first component used the polymer shown in Table 1-1 to Table 1-3 (mixing ratio (mass) in parentheses), and the second component used the above-mentioned trade name "T200E", using an eccentric sheath-core composite nozzle (600 holes) The composition ratio (volume ratio) of the first component/second component is 55/45, the spinning temperature of the sheath component is 260 ° C, the spinning temperature of the core component is 300 ° C, and the nozzle temperature is 290 ° C. In the melt extrusion, a spinning filament having an eccentricity of 25% and a fineness of 6.8 dtex was obtained. The amount of discharge during melt extrusion was 250 g/min, and the extraction speed was 615 m/min.

The obtained spun filament was extended 2.6 times in hot water at 80 ° C and became an extension filament having a fineness of about 3.3 dtex. Next, an oil agent prepared by mixing a potassium C8 alkyl phosphate with a potassium C12 alkylate at a ratio of 35:65 as a fiber treating agent, and imparting 0.3% by mass, was then imparted to the extended filament by a stuffing box type crimper. Peak / 25mm mechanical crimping. Next, the hot air blowing device set at 100 ° C is blown for about 15 minutes, and the annealing portion is simultaneously performed in a relaxed state. Treatment and drying treatment. Thereafter, the filament was cut into a fiber length of 51 mm, and a remarkably composite short fiber was obtained.

Spinning properties and elongation were good in all of the examples and comparative examples.

A fiber web having a density of about 50 g/m ^{2 was} produced from the obtained fiber using a roll carding machine. The first component was melted by using a hot air blowing device set to a temperature higher by 10 ° C than the melting point of LLDPE (Comparative Example 6 is HDPE) constituting the first component of each fiber, and the first component was melted and obtained. The heat is then not woven. However, in Example 2, Example 6, and Comparative Example 1, a nonwoven fabric was produced by heat treatment at 123 ° C and 138 ° C. The obtained significantly crimped composite short fibers and the heat-resistant nonwoven fabric were subjected to the following evaluations.

[Crimping performance]

The crimping of the fibers after the annealing treatment was observed and evaluated according to the following criteria.

A: A good three-dimensional crimp is confirmed.

B: It was confirmed that the crimping depth was large and the wave shape was curled.

C: It is confirmed that the shape of the wave is curled, but the length between the roll and the roll is larger than the crimping depth, and is loosely curled.

D: Only the zigzag crimping imparted by the mechanical crimping was confirmed.

[volume number, crimp ratio]

It is measured based on JIS L 1015 (2010).

[non-woven volume]

The non-woven fabric was cut into a size of 100 mm × 100 mm, and the sample was overlapped by 10 pieces, and measured without using a load, and used as a non-woven fabric volume.

[compressed volume]

The non-woven fabric was cut into a size of 100 mm × 100 mm, and the sample was overlapped by 10 pieces. After applying a load of 5 kgf (49 N), the thickness was measured after 1 minute, and this was taken as the compressed volume.

[volume change rate]

The volume of the nonwoven fabric to be measured and the volume after compression were calculated based on the volume change rate (%) = [(non-woven fabric volume - compressed volume) / non-woven fabric volume] × 100).

[Surface touch]

The surface of the nonwoven fabric was touched and evaluated in accordance with the following evaluation criteria.

A: Very smooth.

B: A little rough.

C: Rough.

[Shrinkage / Cloth]

A roll-type carding machine was used to produce a web having a length × 200 mm × 200 mm and a density of 30 g/m ² , and a hot air blowing device set to a temperature 10 ° C higher than the melting point of the LLDPE constituting the first component of each fiber was used. After heat treatment for 1 minute, the longitudinal and transverse dimensions of the web after the heat treatment were measured, and the web area shrinkage ratio was determined according to the following formula.

Furthermore, observe the fabric quality of the net after heat treatment and the shrinkage rate of the mesh area It was evaluated on the basis of the following criteria.

A: The shrinkage rate of the mesh area is less than 3%, and the surface of the mesh (the surface of the hot air) is smooth.

B: The mesh area shrinkage rate is 5% or less, and the mesh surface (hot air blowing surface) has a slight unevenness.

C: The area shrinkage of the mesh area exceeds 5%, and the unevenness in the surface of the mesh (the surface of the hot air) is remarkable.

[volume response]

The non-woven fabric was cut into a size of 100 mm × 100 mm, and the sample was overlapped by 10 pieces, and a load of 5 kgf (49 N) was applied and left for 12 hours, after which the weight was measured after removing the weight for 10 minutes. Further, from the obtained thickness and the non-woven fabric volume, the volume recovery ratio was calculated in accordance with the volume recovery ratio (%) = (thickness after weight removal/non-woven fabric volume) × 100.

[non-woven strength]

The non-woven fabric transverse direction (CD direction) is used as the stretching direction, and the JIS L 1096 (2010) 6.12.1 A method (strip method) is used as a reference, and a constant-speed tension type tensile tester is used. The tensile test was carried out under the conditions of a test piece width of 5 cm, a jig interval of 10 cm, and a tensile speed of 30 ± 2 cm/min, and the load value at the time of cutting was measured.

The properties of the fibers and nonwoven fabric obtained in each of the examples and the comparative examples are shown in Tables 1-1 to 1-3.

[Table 1-1]

As shown in Table 1-1 to Table 1-3, a non-woven fabric made of a composite short fiber in which a sheath component is composed of a linear polyethylene or a composite short fiber in which a sheath component is composed only of high-density polyethylene (Comparative Example 1) To 3, 6), the volume change rate is small and the flexibility in the thickness direction is not good. The surface of the non-woven fabric formed by the composite short fibers of Comparative Example 6 was not pleasant to the touch. Further, when a linear low-density polyethylene having a density of less than 0.90 g/cm ³ or more than 0.94 g/cm ³ is used, even if it is mixed with low-density polyethylene to form a composite short fiber, the nonwoven fabric produced therefrom cannot be imparted. Good surface feel (Comparative Example 4), or bulkiness and volume recovery rate did not show satisfactory characteristics (Comparative Example 5).

A linear short-density polyethylene having a density in the range of 0.90 g/cm ³ to 0.94 g/cm ³ is mixed with low-density polyethylene to form a composite short fiber of a sheath component, and the non-woven fabric made of the composite short fiber is fluffy Further, the thickness direction showed good flexibility (small volume change rate) (Examples 1 to 13). In Examples 1 and 9, since the mixing ratio of the low-density polyethylene is small, the evaluation of shrinkage/cloth quality is low, but good characteristics are exhibited at other points, and it can be sufficiently practical depending on the application.

Comparing Example 6 with Comparative Example 2, it was found that the addition of low-density polyethylene not only imparts bulkiness, flexibility in the thickness direction, and improved volume recovery, but also enhances the surface feel of the nonwoven fabric. This means that the low-density polyethylene has a function as a soft component for improving the touch of a relatively high-density linear polyethylene.

In order to confirm the effect of the nonwoven fabric of Example 5 as a surface material, the nonwoven fabric liquid absorption and liquid passage performance were measured by the following method.

[run-off]

(1) The non-woven fabric was cut into a longitudinal direction (mechanical direction) × a horizontal direction of 18 cm × 7 cm, and was used as a sample.

(2) On the support table having a cross section of the sample which has a slope of a 45-degree angle with respect to the horizontal plane and a slightly vertical isosceles triangle, four sheets of Nippon Paper crecia Co., Ltd. "KIMTOWEL (registered trademark) ) and placed a fixed non-woven sample on it.

(3) A total of 6 g of physiological saline was dripped at a rate of 1 g/10 sec from a microchip pump or a burette at a position of 1 cm from the upper end of the non-woven surface, and the injected physiological saline was all absorbed into the non-woven fabric, and the physiological condition was measured. The water droplets of the saline water disappear from the surface of the non-woven fabric, and the distance between the water droplets of the physiological saline solution and the non-woven surface of the physiological saline solution is determined.

[liquid absorption rate, liquid residual amount, reverse flow rate]

(1) In order to measure the liquid absorption speed, the liquid residual amount, and the reverse flow rate, the following items were prepared.

Absorber: KIMTOWEL (registered trademark) 2 groups.

A plate with an injection cylinder (1 cm inside the lower portion of the cylinder) is attached.

Artificial menstrual blood (viscosity 8MPa.s).

The filter paper (AD V ANTEC (registered trademark) No. 2 manufactured by Toyo Filter Co., Ltd.) was 10 cm × 10 cm.

Weight (5kg, 287 g × 2).

(2) Method

The liquid absorption rate, the liquid residual amount, and the reverse flow rate were measured in the following order.

(i) A non-woven fabric sample was placed on the KIMTOWEL (registered trademark) 2 group, and a flat plate with an injection cylinder was placed thereon, and the ends of the flat plate were placed at a weight of 287 g.

(ii) 5 ml of artificial menstrual blood was injected from the canister. At this time, the time (the liquid absorption time) until the artificial menstrual blood could not be seen on the surface of the non-woven fabric (the artificial menstrual blood of the liquid could not be confirmed) was measured, and this was taken as the liquid absorption speed.

(iii) The plate was removed and allowed to stand for 10 minutes.

(iv) After 10 minutes, the non-woven fabric is clamped with filter paper (8 pieces), and the residual artificial blood of the non-woven fabric is sucked on the filter paper to measure the quality of the filter paper (the difference between the quality of the filter paper before absorbing artificial menstrual blood and the filter paper after absorbing artificial menstrual blood is equivalent to Liquid residue).

(v) The non-woven fabric was placed back on the absorbent body, and a new filter paper (8 pieces) was placed on the non-woven fabric and placed at a weight of 5 kg for 10 seconds. Then, the quality of the filter paper was measured (the difference between the quality of the filter paper placed on the non-woven fabric and the filter paper placed on the non-woven fabric and weighted was equivalent to the reverse flow rate).

(vi) Go back to the above (i) and perform the second measurement.

The measured liquid absorption rate, liquid residual amount, and reverse flow rate are shown in Table 2.

As shown in Table 2, the non-woven fabric of Example 5 has the function of the absorbent body which is absorbed by the artificial menstrual blood and is absorbed, and further, as the surface of the sanitary article, the liquid residual amount and the liquid flow rate are reversed. material.

[Evaluation of surface properties and compression characteristics by KES]

The fibers obtained in Examples 2 and 6 and Comparative Examples 1 and 6 were respectively used, and a fiber web having a density of about 50 g/m ^{2 was} produced by a roll carding machine. The temperature was set to be 10 ° C higher than the melting point of LLDPE or HDPE constituting the first component of each fiber (Example 2: 128 ° C, Example 6: 130 ° C, Comparative Example 1:128 ° C, Comparative Example 6: 140 ° C) The hot air blowing device heats the obtained fiber web for 1 minute to melt the first component, and obtains heat and then non-woven fabric.

In order to evaluate the surface feel and the softness, bulkiness, and volume recovery (elasticity) of the heat and non-woven fabric, the surface properties and compressive properties were measured based on KES (KaWabata Evaluation System). Evaluation.

Specifically, in order to evaluate the surface characteristics, a surface friction test of heat and non-woven fabric was performed, and the average friction coefficient (MIU) and the variation of the average friction coefficient (MMD) as surface property values were measured. For the surface friction test of heat followed by non-woven fabric. For the measurement, a KES-SE friction feeling tester manufactured by Keskato Co., Ltd. was used. At the time of measurement, the surface on which the hot air was blown when the heat was not produced was used as the measurement surface, and a static load of 25 gf was applied to the frictional material, and the friction was moved in the direction of the transverse direction of the parallel nonwoven fabric at a moving speed of 1 mm/sec to measure the heat. Non-woven MIU, MMD.

In order to evaluate the compression characteristics of the heat and then the nonwoven fabric, specifically, the heat test is performed on the non-woven fabric, and the load-displacement curve is used as the compression characteristic value, and the compression hardness (LC), the compression energy (WC), and the compressive elastic energy (RC) are measured. ), T0 (thickness at a load of 0.5 gf/cm ² ), TM (thickness of a load of 50 gf/cm ² ), and compression ratio (EMC). For the compression test and the compression characteristic value of the heat-non-woven fabric, a KES-G5 HANDY compression tester manufactured by Keskato Co., Ltd. was used. In the measurement, a circular compression plate having an area of 2 cm ² was used as a compressor, SENS: 2, DEF sensitivity: 20 was set, and the above-mentioned compressed body was compressed for heat and then non-woven at a compression speed of 0.02 cm/sec, and compressed. The load is 50 gf/cm ² . After the load reached 50 gf/cm ² , the compression was removed so that the moving speed of the compressed object was 0.02 cm/sec, and the compression characteristic value was measured. The measurement results are shown in Table 3.

In the results of the surface characteristics and the compression characteristics of the KES shown in Table 3, when the compression characteristics of Example 2 and Example 6 and Comparative Example 6 were compared, the LC of Examples 2 and 6 was smaller than that of Comparative Example 6, RC and EMC are larger than the non-woven fabric of Comparative Example 6. This is the first component of the significantly crimpable composite short fibers used in Examples 2 and 6, and contains a linear polyethylene having a bending elastic modulus lower than that of high-density polyethylene as a resin component. By using a linear polyethylene, it is possible to obtain a heat which is small in LC and which is soft to be deformed by the load, and then is not woven. In addition, it is considered that since the linear elastic modulus of the linear polyethylene is small, The load is more deformed, so the EMC will become larger. In other words, the non-woven fabric containing the remarkably crimped composite short fibers of the present invention is considered to be softly deformed with respect to the load in the thickness direction, and is heat-resistant non-woven fabric because of the large amount of deformation. Further, the first component is a remarkably crimped composite short fiber composed of a resin component containing a large amount of linear polyethylene, and the heat composed of the remarkably crimped composite short fiber is followed by non-woven fabric (including Comparative Example 1). Since the RC is larger than Comparative Example 6, the linear polyethylene itself is more elastic than the higher density polyethylene, so it is presumed to be an elastic resin.

Comparing the non-woven fabrics of Examples 2 and 6 with the nonwoven fabric of Comparative Example 1, it is considered that the nonwoven fabric of Comparative Example 1 has the same value as that of Example 6 because of the influence of only the linear polyethylene, but Comparative Example 1 The non-woven fabric is not only large in LC, but also WC and EMC are smaller than those in Embodiments 2 and 6. The non-woven fabric of Comparative Example 1 is a non-woven fabric having a small volume and a small bulk and a high density at the beginning, and therefore is presumed to be a non-woven fabric which is hard to be deformed in the thickness direction and has no soft feeling.

When the surface characteristics of the non-woven fabrics of Examples 2 and 6 and the non-woven fabrics of Comparative Examples 1 and 6 were compared, the non-woven fabrics of Examples 2 and 6 showed that the MIU of the non-woven fabric surface sliding difficulty was large, and the non-woven fabric surface was difficult to slide. On the other hand, the MMD showing the surface roughness of the nonwoven fabric was smaller than the non-woven fabrics of Examples 2 and 6. From the result, the crimped composite short fiber comprising the first component satisfying the resin component of the linear polyethylene and the low density polyethylene in a specific density range, and the non-woven fabric using the crimped composite short fiber The MIU of the non-woven surface is large but the MMD is small. Therefore, the non-woven fabric has a moderate friction with the skin, so when it comes into contact with the skin, there is friction between the skin and the non-woven fabric. The feeling of attaching the non-woven fabric to the skin, but the friction is small, that is, it is not rough, so the touch is smooth and gives a unique feeling of touch (smoothness and moist feeling).

In Comparative Example 1 and Comparative Example 6, the average friction coefficient MMD was large. The roughness of the MMD, that is, the surface of the non-woven fabric is affected not only by the surface of the fiber constituting the surface of the non-woven fabric, but also by the difficulty of the movement of the fiber (the ease of deformation) when the friction of the skin and the friction test moves on the surface of the non-woven fabric. Therefore, it is considered that the more difficult the fiber is to be deformed, the more difficult the fiber on the surface to move on the skin and the frictional movement, so the force required to move the fiber by the skin and the frictional agent becomes large. The non-woven fabric of Comparative Example 6 is composed of a high-density polyethylene having a large bending elastic modulus and is a fiber which is difficult to be deformed, and is therefore required to move the skin and the frictional force. It will become bigger in an instant, and the MMD will become larger. Further, in the non-woven fabric of Comparative Example 1, the first component of the substantially crimpable composite short fiber constituting the nonwoven fabric is composed of linear polyethylene. Therefore, it is presumed that the constituent fibers themselves are fibers which are easily deformed, but the nonwoven fabric is smaller in volume (in other words, It is a non-woven fabric with a high density, so the number of fibers constituting the surface of the non-woven fabric is increased. Therefore, when the skin and the friction are moved, compared with the nonwoven fabrics of Examples 2 and 6 (the specific volume is large and the density is small), the fibers in the non-woven fabric of Comparative Example 1 hinder the movement of the skin and the friction, and therefore the movement is presumed. The force required for the skin and the friction will increase in an instant, and the MMD will become larger.

(industrial availability)

The remarkable crimped composite staple fiber of the present invention is excellent in softness and simultaneous processability (especially high-speed carding property), and can be imparted as a non-woven fabric when it is not woven. Good surface feel, bulkiness, softness in the thickness direction and volume recovery. Therefore, the significantly crimped composite staple fiber of the present invention is particularly suitable for constituting the surface material of sanitary articles, and is also suitable for constituting other fibrous products such as wet tissues, wipes, cosmetic materials, women's underwear pads, shoulder pads, vehicles. Use shock absorbing materials, base materials for floor heating, cushioning materials and packaging materials.

1‧‧‧ first ingredient

2‧‧‧Second ingredients

3‧‧‧The position of the center of gravity in the fiber cross section of the second component

4‧‧‧Center of gravity in the fiber cross section of composite staple fibers

5‧‧‧Radius in the fiber cross section of composite short fibers

10‧‧‧Composite staple fiber

Fig. 1 is a view showing a fiber cross section of a significantly crimped composite short fiber in an embodiment of the present invention.

Fig. 2A to Fig. 2 are views showing a crimped form of a substantially crimpable composite short fiber in an embodiment of the present invention.

Fig. 3 is a view showing a conventional mechanical crimping type.

Fig. 4 is a view showing a crimped form of a substantially crimpable composite short fiber in another embodiment of the present invention.

1‧‧‧ first ingredient

2‧‧‧Second ingredients

3‧‧‧The position of the center of gravity in the fiber cross section of the second component

4‧‧‧Center of gravity in the fiber cross section of composite staple fibers

5‧‧‧Radius in the fiber cross section of composite short fibers

10‧‧‧Composite staple fiber

Claims (9)

A substantially crimped composite short fiber comprising a composite short fiber of a first component and a second component, wherein the first component comprises a linear polyethylene having a density of 0.90 g/cm ³ to 0.94 g/cm ³ and a density a low density polyethylene of 0.91 g/cm ³ to 0.93 g/cm ³ ; and the first component is such that the low density polyethylene accounts for 5% by mass of the total mass of the linear polyethylene and the low density polyethylene. The low-density polyethylene is contained in a form of up to 25% by mass; and the second component contains 50% by mass or more of polyethylene terephthalate having a melting point higher than a melting point of 40 ° C or more higher than that of the linear polyethylene constituting the first component. And/or polybutylene terephthalate, and without polytrimethylene terephthalate; in the cross section of the fiber, the first component accounts for at least 20% of the surface of the fiber, and the position of the center of gravity of the second component deviates from the center of gravity of the fiber Position; and the composite staple fiber has at least one crimp selected by wave-shaped crimping and spiral crimping. The remarkably crimped composite short fiber according to claim 1, wherein the linear polyethylene is a metallocene catalyst. The remarkably crimped composite staple fiber according to claim 1, wherein the melting point of the linear polyethylene before spinning is higher than the melting point of the low-density polyethylene before spinning. The significantly crimped composite staple fiber according to any one of claims 1 to 3, wherein the measurement is based on JIS L 1015 2010 When the number of crimps and the crimp ratio of the composite short fibers are determined, the ratio of the crimp ratio to the number of crimps (the crimp ratio/the number of crimps) is 1.2 or less. A method for producing a composite short fiber, which comprises a method for producing a composite short fiber comprising a first component and a second component, comprising: a linear polyethylene having a density of from 0.90 g/cm ³ to 0.94 g/cm ³ , and Low density polyethylene having a density of 0.91 g/cm ³ to 0.93 g/cm ³ and low density polyethylene constituting the first component of 5 to 25 mass% of the total mass of the linear polyethylene and the low density polyethylene And polyethylene terephthalate and/or polybutylene terephthalate containing 50% by mass or more of a melting point higher than a melting point of a linear polyethylene constituting the first component by 40 ° C or higher and not a second component comprising polytrimethylene terephthalate, in a fiber cross section, wherein the first component comprises at least 20% of the surface of the fiber, and the position of the center of gravity of the second component is melted from the center of gravity of the fiber, And obtaining a spinning filament; the range of the spinning filament at a Tg ₂ ° C to 95 ° C (but the glass transition point of the polymer component having the highest glass transition point among the polymer components contained in the Tg ₂ -based second component) The temperature inside extends 1.8 to 5 times; for the extended filament, the number of crimps is 5 peaks / 25 mm to 25 The peak/25 mm range is imparted to the mechanical crimping, and the annealing treatment is performed at a temperature in the range of 50 to 115 ° C; the annealed filament is cut into a length of 1 mm to 100 mm; and the composite short fiber has a wave shape At least one type of crimp selected by the spiral crimping. A fiber assembly comprising 20% by mass or more of the substantially crimpable composite staple fiber of any one of claims 1 to 4. The fiber assembly according to claim 6, wherein the fibers are thermally entangled with each other by the first component of the substantially crimpable composite short fibers. A surface material for a sanitary article, which is formed by the fiber assembly described in claim 6 or 7. A sanitary article comprising the surface material described in claim 8 of the patent application.