JP6101012B2 - Divisible uneven composite fiber and non-woven fabric using the same - Google Patents

Description

  In the present invention, the fiber surface portion composed of the low melting point component (B) of the splittable composite fiber having a fiber cross section in which the high melting point component (A) and the low melting point component (B) are bonded to each other has an uneven shape. The present invention relates to a splittable uneven composite fiber, a method for efficiently manufacturing the splittable uneven composite fiber, and a nonwoven fabric using the fiber.

  Since a nonwoven fabric can generally be manufactured directly from fibers without passing through a spinning process or a twisting process, the manufacturing process is simpler than that of a woven fabric or a knitted fabric. Nonwoven fabrics having such advantages are widely used for sanitary materials and daily necessities. Among these nonwoven fabrics, polypropylene-based nonwoven fabrics are used, for example, as surface materials for paper diapers and napkins, simple wipers, separators for secondary batteries, filters (filter materials), and the like. In such a nonwoven fabric, a composite fiber having a sheath-core structure, for example, a sheath-core composite fiber having a polypropylene resin as a core material and a polyethylene resin as a sheath material is used. The sheath-core composite fiber is subjected to a stretching process in order to increase the strength.

Moreover, as a manufacturing method of a short fiber nonwoven fabric, a heat bonding composite fiber is arranged using a card machine, laminated and entangled so as to have a predetermined basis weight, and then the low melting point component of the composite two components is used. A method of forming a nonwoven fabric by fusing fibers together by melting them is known.
The heat-adhesive conjugate fiber can be made into a non-woven fabric relatively easily by heat from hot air or a heat roller without using an adhesive. As such a heat-adhesive conjugate fiber, various types have been developed so far, for example, a heterogeneous polymer sheath-core type conjugate fiber such as a polyethylene-polypropylene conjugate fiber and a polyethylene-polyethylene terephthalate conjugate fiber, and a copolyester. -Various fibers have been developed, such as homogeneous polymer sheath-core composite fibers such as polyethylene terephthalate composite fibers. Moreover, when obtaining the nonwoven fabric which uses a heat bondable sheath-core type composite fiber as a material, the hot-air fusion method and the hot roll fusion method are properly used depending on the use of the nonwoven fabric.
That is, the hot air fusion method is generally employed when emphasizing the tactile sensation and texture of the obtained nonwoven fabric, and the hot roll fusion method is employed when emphasizing the strength of the obtained nonwoven fabric.

  For example, (1) a polyester composition containing 20 to 50% by mass of a poly (meth) acrylate-based resin and a polyester substantially free of a poly (meth) acrylate-based resin having a mass ratio of 3:97 to 40:60 The composite spinning is carried out at a rate of 3,500 m / min or less, and the obtained undrawn yarn is drawn to a maximum draw ratio of 0.62 to 0.91 times at a drawing temperature of 55 to 95 ° C. (2) A non-woven fabric composed of a composite long fiber composed of at least a non-elastomeric resin and an elastomer resin, wherein the composite long fiber is The composite long fiber has a non-elastomeric resin / elastomeric resin volume ratio (%) in the range of 30/70 to 5/95, and has a fineness of the composite long fiber. (3) Polyester [A] having a melt viscosity of 100 Pa · s or more when discharging a spinning stock solution from a spinneret is a sheath component. Polyester [B] of 20 Pa · s or less is a core component, and the difference in melt viscosity between the polyesters [A] and [B] is more than 100 Pa · s and less than 350 Pa · s, and the high melting point component (A) A multifilament yarn made of a composite fiber that is thick and thin due to thick and thin, and has a special spotted yarn having a fineness of 15 pieces / m or more in the length direction of the yarn (for example, see Patent Document 3) ) Is disclosed.

  On the other hand, Patent Document 4 discloses that, in the case of a modified cross-section fiber having a continuous groove in the vertical direction, a capillary phenomenon appears in the groove and the effect of diffusing water (large bleeding) is increased. Yes.

Patent Document 5 proposes a heat-splitting composite fiber having a cross-sectional shape in which a high-melting polymer segment and a low-melting polymer segment are bonded to each other.
Further, Patent Document 6 discloses a composite fiber composed of two components (A) a thermoplastic polyester component and (B) a polyolefin component, and a plurality of branched portions are radially formed from a reservoir portion formed at the center of the fiber. The extended main segment composed of one of the component (A) and the component (B) and a plurality of sub-segments defined by the main segment and composed of the other of the component (A) and the component (B) are joined to each other. An exfoliation split type composite fiber having a cross section of the fiber has been proposed.
Patent Document 5 provides a heat-splitting composite fiber suitable for producing a tactile nonwoven fabric excellent in texture, and Patent Document 6 describes a peel-splitting type suitable for obtaining a non-woven fabric made of ultrafine fibers with a soft touch and high density. The purpose is to provide composite fibers.

JP 2001-164428 A JP 2004-250795 A JP-A-8-188925 International Publication No. 2009/150745 Japanese Patent No. 2904966 Japanese Patent No. 3294665

However, the composite fiber having irregularities on the surface described in Patent Document 1 does not use a polyolefin-based resin for both the core component and the sheath component, and is made of a polyester-based resin composition. This is a technique that regulates the draw ratio with respect to the temperature and the maximum draw ratio, and causes the sheath component to exhibit irregularities.
The elastic long-fiber nonwoven fabric described in Patent Document 2 is a composite fiber composed of an elastomer resin such as styrene-ethylene-butylene-styrene block copolymer (SEBS) and a non-elastomeric resin such as a polypropylene resin. A composite non-elastomeric resin / elastomer resin volume ratio of the composite fiber, a fineness of the composite fiber of 5 dtex or less, and a composite long fiber having a helical structure and an uneven structure formed on the surface. It is the comprised nonwoven fabric.
Further, the special patch described in Patent Document 3 has polyester [A] having a melt viscosity defined as a sheath component, polyester [B] as a core component, and the melt viscosity of polyesters [A] and [B]. This is a multifilament yarn made of a composite fiber that is thick and thin due to the thick and thin high melting point component (A) that defines the difference.
In these techniques, all are techniques for forming irregularities on the surface of the composite fiber itself, and high-speed spinning is essential, can only be applied to thin fibers, and the resulting irregularities are relatively small. It was a thing.

The technique described in Patent Document 4 includes 20% by mass or more of a sheath-core polyester fiber, and the polyester fiber contains ethylene glycol in the low melting point component (B), and the low melting point component (B) / high This is a technique for providing a water-absorbing quick-drying woven or knitted fabric using a modified cross-section fiber that defines the mass ratio of the melting point component (A). And, in the case of a modified cross-section fiber having a continuous groove in the longitudinal direction, a capillary phenomenon appears in the groove, and the woven or knitted fabric using the modified cross-section fiber has a large effect of diffusing water (large bleeding). It is disclosed.
However, when producing a non-woven fabric using this modified cross-section fiber, it is preferably a heat-bonded composite fiber. It turns out that the nozzle for manufacturing is expensive and leads to high costs, and the sheath component melts and aggregates at the time of heat fusion, so it is difficult to form a sharp shape, and the capillarity manifesting power of the obtained nonwoven fabric is relatively small It was.

  Patent Document 5 and Patent Document 6 do not disclose a technical idea for improving the tactile sensation by forming irregularities on the fiber surface or improving the water absorption of the nonwoven fabric.

  The present invention has been made under such circumstances, and a splittable concavo-convex composite fiber capable of providing a nonwoven fabric having a large performance (effect) for absorbing water (water retention), and an effective method for producing the splittable concavo-convex composite fiber. And the objective is to provide the nonwoven fabric which uses the fiber.

  As a result of intensive studies to achieve the above object, the present inventors have found that a high melting point component (A) containing a crystalline thermoplastic resin, a polyolefin resin (a), and an amorphous resin (b) A composite fiber comprising a low-melting-point component (B) comprising a resin composition comprising a high-melting-point component (A) and a low-melting-point component (B) having a cross-sectional shape bonded to each other The present invention was completed by finding that the object can be achieved by using a splittable uneven composite fiber in which the fiber surface portion composed of the low melting point component (B) has an uneven shape.

That is, the present invention
[1] A composite comprising a high melting point component (A) containing a crystalline thermoplastic resin and a low melting point component (B) comprising a resin composition containing a polyolefin resin (a) and an amorphous resin (b). The composite fiber has a cross-sectional shape in which the high melting point component (A) and the low melting point component (B) are joined to each other, and the fiber surface portion composed of the low melting point component (B) has an uneven shape. A splittable concavo-convex composite fiber, characterized in that
[2] The melting point of the polyolefin resin (a) is lower than the melting point of the crystalline thermoplastic resin, and the unstretched composite fiber is stretched at a temperature not higher than the glass transition point (Tg) of the amorphous resin (b). And the division according to [1], wherein the surface of the low-melting-point component (B) is formed with unevenness over the fiber axis direction of the low-melting-point component (B) by heat treatment when the drawn yarn is made into a non-woven fabric. Concavo-convex composite fiber,
[3] The splittable uneven composite fiber according to [2], wherein the amorphous resin (b) has a glass transition point (Tg) higher than the melting point of the polyolefin resin (a),
[4] In the radial cross section of the composite fiber, the high melting point component (A) and the low melting point component (B) are bonded substantially radially from the center of the fiber toward the fiber surface. The splittable uneven composite fiber according to any one of the above,
[5] The crystalline thermoplastic resin of the high melting point component (A) is crystalline polypropylene or polyethylene terephthalate, and the polyolefin resin (a) of the low melting point component (B) is high density polyethylene. 4] The splittable concavo-convex composite fiber according to any one of
[6] The splittable concavo-convex composite fiber according to any one of [1] to [5], wherein the amorphous resin (b) is a cyclic olefin copolymer and / or polycarbonate.
[7] The splittable concavo-convex composite fiber according to [6], wherein the amorphous resin (b) is a cyclic olefin copolymer,
[8] Any of [1] to [7], wherein the content ratio of the polyolefin resin (a) and the amorphous resin (b) in the low melting point component (B) is 97: 3 to 85:15 by mass ratio The splittable uneven composite fiber according to crab,
[9] A high melting point component (A) containing a crystalline thermoplastic resin, a polyolefin resin (a) having a melting point lower than the melting point of the crystalline thermoplastic resin of the high melting point component (A), and an amorphous resin ( b) a step of melt-spinning unstretched composite fibers joined together with a low-melting-point component (B) comprising a resin composition comprising the resin composition, and the unstretched composite fibers from Tg to the melting point of the polyolefin resin (a) And a step of thermally stretching at a temperature equal to or lower than the Tg of the amorphous resin (b), and a method for producing a splittable concavo-convex composite fiber,
[10] In the step of melt spinning the composite fiber, the high melting point component (A) and the low melting point component (B) are joined together in a radial pattern from the center of the fiber toward the fiber surface in the radial cross section of the composite fiber. Spinning by adjusting the melt viscosity of the high-melting component (A) and the melt viscosity of the low-melting component (B) in the spinning head using a spinning device equipped with a possible spinning head. Production method of splittable uneven composite fiber,
[11] The adjustment of the melt viscosity, melt flow rate (MFR melt flow rate of the crystalline thermoplastic resin having a high melting point component (A) (MFR _A) and the polyolefin resin having a low melting point component (B) (a) _B ) is a method for producing a splittable uneven composite fiber according to [10], wherein MFR _A ≧ MFR _B , and a splittable uneven composite fiber according to any one of [12] [1] to [8] Non-woven fabric,
Is to provide.

  ADVANTAGE OF THE INVENTION According to this invention, the splittable uneven | corrugated conjugate fiber which can manufacture a nonwoven fabric with the large performance (effect) which absorbs water (water retention) by expression of a capillary phenomenon, the efficient manufacturing method of this splittable uneven conjugate fiber, and this split The nonwoven fabric formed using a concavo-convex composite fiber can be provided.

It is a schematic cross section which shows the example of the high melting point component ( A ) and low melting point component (B) joining pattern in the splittable uneven | corrugated conjugate fiber of this invention. It is a cross-sectional photograph which shows the joining pattern of the high melting-point component (A) and the low melting-point component (B) in the cross section of the composite unstretched fiber which has a radial joint cross section. It is a SEM photograph of (a) splittable uneven composite unstretched fiber, (b) splittable uneven composite stretched fiber, and (c) obtained hot-air fused nonwoven fabric in Example 1. It is the SEM photograph which shows the state of the fiber after hot-air fusion | melting about (a) the fiber after extending | stretching obtained by Example 2, and (b) the obtained nonwoven fabric. (A) The SEM photograph of the fiber after extending | stretching obtained by Example 4, (b) The SEM photograph which shows the state of the fiber after hot-air fusion | melting about the obtained nonwoven fabric. It is the SEM photograph which shows the state of the fiber after hot-air fusion | melting about (a) the fiber after extending | stretching obtained by Example 9, and (b) the obtained nonwoven fabric. It is the SEM photograph which shows the state of the fiber after hot-air fusion | melting about (a) the fiber after a stretch obtained by Example 10, and (b) the obtained nonwoven fabric. It is the SEM photograph which shows the state of the fiber after hot-air fusion | melting about (a) the fiber after extending | stretching obtained by the comparative example 1, and (b) the obtained nonwoven fabric. It is the SEM photograph which shows the state of the fiber after hot air fusion | melting about (a) the fiber after extending | stretching obtained by the comparative example 2, and (b) the obtained nonwoven fabric.

First, the splittable concavo-convex composite fiber of the present invention will be described.
The splittable concavo-convex composite fiber of the present invention is a low-melting-point component comprising a resin composition containing a high-melting-point component (A) containing a crystalline thermoplastic resin, a polyolefin resin (a) and an amorphous resin (b). (B), the composite fiber having a cross-sectional shape in which the high melting point component (A) and the low melting point component (B) are joined to each other, and the fiber consisting of the low melting point component (B) The surface portion has an uneven shape.

In the present invention, “the fiber surface portion composed of the low melting point component (B) has an uneven shape” means that irregularities are formed on the portion occupied by the low melting point component on the fiber surface (outer peripheral surface). Means presenting. The irregular irregularities are formed by the amorphous resin blended in the low melting point component, and the irregularities appear by heat stretching and further heat fusion treatment when forming a nonwoven fabric.
The composite fiber “having a cross-sectional shape in which the high melting point component (A) and the low melting point component (B) are joined to each other” means that a cross section perpendicular to the fiber axis (hereinafter referred to as “fiber cross section”) is shown in FIG. In the state as shown in (a) to (g), the high melting point component (A) and the low melting point component (B) are joined to each other and are continuous in the fiber axis direction.
“Dividability” of “divided concavo-convex composite fiber” means that the high melting point component (A) and the low melting point component (B) are subjected to high temperature treatment, water jet treatment, card treatment depending on the difference in thermal shrinkage between the components. This means that the fiber has the possibility of being finely divided by dividing it into a high melting point component (A) and a low melting point component (B) by mechanical treatment such as It doesn't mean.
The cross-sectional shape of the splittable concavo-convex composite fiber of the present invention does not have to be circular, but may be rectangular as shown in FIGS. 1 (f) and (g), and is elliptical, star-shaped, cross-shaped. An irregular cross section such as a mold may be used.

  The splittable concavo-convex composite fiber of the present invention is a composite unstretched structure in which a high melting point component (A) and a low melting point component (B) are bonded substantially radially from the center of the fiber toward the fiber surface in a cross section in the fiber radial direction. It can be a fiber. That is, a composite unstretched fiber in which two components are joined as shown in FIG. 1 (a) or as shown in FIGS. 2 (a) to 2 (e) can be obtained.

[Material constituting high melting point component (A)]
In the splittable concavo-convex composite fiber of the present invention, a crystalline thermoplastic resin is used as a material constituting the high melting point component (A) (hereinafter sometimes referred to as a high melting point component material).
The crystalline thermoplastic resin is required to have a melting point higher than that of the polyolefin resin (a) described above. For example, crystalline polypropylene, crystalline polyester such as polyethylene terephthalate or polybutylene terephthalate, polyamide (nylon) , Aromatic polyester resins (liquid crystal polymers) can be used, and these may be used alone or in combination of two or more. Among these, crystalline polypropylene is preferable because it has a relatively low melting point and is excellent in processability and cost.

  As this crystalline polypropylene, an isotactic polypropylene resin is preferably used. Among them, those having an isotactic pentad fraction (IPF) of preferably 85% or more, more preferably 90% or more are advantageous. The Q value (weight average molecular weight / number average molecular weight Mw / Mn ratio), which is an index of molecular weight distribution, is 6 or less, and the melt flow rate (MFR) (temperature 230 ° C., load 2.16 kg) is 3 to 100 g / 10 min. The range of is preferable. If the IPF is less than 85%, the stereoregularity is insufficient and the crystallinity is low, and the physical properties such as strength of the resulting composite fiber are poor.

The isotactic pentad fraction (IPF) (generally also referred to as mmmm fraction) is a side chain with respect to the main chain of carbon-carbon bonds composed of any five consecutive propylene units. This shows the proportion of the three-dimensional structure in which two methyl groups are located in the same direction. Pmmmm (5 propylene units are isotactic) in the isotope carbon nuclear magnetic resonance spectrum ( ¹³ C-NMR). From the absorption intensity derived from the methyl group of the third unit at the bonded site and Pw (absorption intensity derived from all methyl groups of the propylene unit), the formula IPF (%) = (Pmmmm / Pw) × 100
Can be obtained.

Further, the polypropylene may be a propylene homopolymer or a copolymer of propylene and an α-olefin (for example, ethylene, butene-1, etc.).
That is, as crystalline polypropylene, for example, isotactic propylene homopolymer having crystallinity, ethylene-propylene random copolymer having a small ethylene unit content, homo-part consisting of propylene homopolymer and ethylene unit content A propylene block copolymer composed of a copolymer part composed of an ethylene-propylene random copolymer having a relatively large amount of each of the above-mentioned propylene block copolymers, and each homo part or copolymer part in the propylene block copolymer further includes butene-1, etc. Examples thereof include crystalline propylene-ethylene-α-olefin copolymers formed by copolymerizing α-olefins.
In the present invention, the resin composition that is the low-melting-point component (B) material and the crystalline thermoplastic resin that is the high-melting-point component (A) material include various additives such as a weathering agent as necessary. , Heat stabilizers, flame retardants, colorants, deodorants, antibacterial agents, fragrances, and the like.

[Material constituting low melting point component (B)]
In the splittable concavo-convex composite fiber of the present invention, a polyolefin resin (a) and an amorphous resin (b) are used as materials constituting the low melting point component (B) (hereinafter sometimes referred to as a low melting point component material). ) Is used in combination.
(Polyolefin resin (a))
The polyolefin resin (a) used as one component of the low melting point component (B) needs to have a melting point lower than the melting point of the crystalline thermoplastic resin used as the material constituting the high melting point component (A). . When the melting point of the polyolefin-based resin (a) does not satisfy the above conditions, it is difficult to obtain a splittable concave-convex composite fiber having thermal adhesiveness, making it difficult to produce a nonwoven fabric by hot air fusion method, and for example, producing a nonwoven fabric. Even if, irregular irregularities are hardly formed on the surface of the low melting point component (B).
The polyolefin-based resin (a) is not particularly limited as long as it has the properties described above. For example, an ethylene-based polymer such as high-density, medium-density, low-density polyethylene or linear low-density polyethylene, A copolymer of propylene and another α-olefin, specifically, a non-crystalline propylene-based heavy polymer such as propylene-butene-1 random copolymer, propylene-ethylene-butene-1 random copolymer, or soft polypropylene. Examples thereof include polymer and poly-4-methylpentene-1. These polyolefin resin (a) may be used individually by 1 type, and may be used in combination of 2 or more type.
Among these, high density polyethylene (melting point: 130 ° C.) is preferable in consideration of spinnability and cost. The melt flow rate (MFR) (temperature 190 ° C., load 2.16 kg) of high-density polyethylene is preferably in the range of 3 to 60 g / 10 min.

(Amorphous resin (b))
As a component of the low melting point component (B), the amorphous resin (b) used in combination with the above-described polyolefin resin (a) needs to have a glass transition point (Tg) higher than the stretching temperature. The reason for this is to form irregularities due to the difference in stretchability between the polyolefin resin (a) and the amorphous resin (b) in the low melting point component (B) at the stretch temperature.
Examples of the amorphous resin (b) include cyclic olefin polymers and polycarbonate.
Examples of the cyclic olefin polymer include a cyclic olefin copolymer that is a copolymer of ethylene and norbornene [manufactured by Polyplastics Co., Ltd., registered trademark “TOPAS”, Tg of 5013 = 134 ° C.], a copolymer of ethylene and cyclic olefin. Cyclic olefin copolymer as a polymer [Mitsui Chemicals, registered trademark “Apel”, APL5014DP Tg = 135 ° C.], cycloolefin polymer obtained by metathesis ring-opening polymerization of norbornene derivative [manufactured by Nippon Zeon, registered trademark “ ZEONEX ”, Tg of 480R = 138 ° C.], cycloolefin polymer having a tricyclodecane structure [manufactured by JSR, registered trademark“ ARTON ”, Tg = 171 ° C.] and the like.
In the present invention, the amorphous resin (b) may be used singly or may be used in combination of two or more, and in particular, a cyclic olefin copolymer and / or polycarbonate is used from the viewpoint of performance. preferable.

  When a cyclic olefin copolymer is used as the amorphous resin (b), melt volume rate (MVR) is generally used as an index of fluidity of the cyclic olefin copolymer, that is, melt viscosity. Therefore, as the amorphous resin (b) of the low melting point component (B) of the splittable concavo-convex composite fiber of the present invention, MVR is based on the test method ISO 1133 from the viewpoint of melt spinning stability and stretchability, and measurement conditions: In 260 degreeC and 2.16kg, 10 ml / 10min or more is preferable, and 14 ml / 10min or more is more preferable. The MVR, which is an index of fluidity, is, for example, when an ethylene / norbornene copolymer containing an ethylene unit and a norbornene unit is selected as the cyclic olefin copolymer, the polymerization degree X of the ethylene unit and the polymerization degree Y of the norbornene unit. The molecular weight based on the above and the molecular weight distribution of the whole cyclic olefin copolymer can be selected from those regulated.

  In the splittable concavo-convex composite fiber of the present invention, the resin composition used as the low-melting-point component (B) material is a polyolefin-based resin (described above) from the viewpoint of forming irregular concavo-convex shapes on the surface of the low-melting-point component (B). The content ratio of a) and the amorphous resin (b) is preferably 97: 3 to 85:15, more preferably 95: 5 to 90:10, by mass ratio.

[Production method of splittable uneven composite fiber]
The splittable concavo-convex composite fiber of the present invention comprises a high melting point component (A) containing a crystalline thermoplastic resin, a polyolefin resin (a) having a melting point lower than that of the high melting point component (A), and a glass higher than the stretching temperature. A step of melt-spinning unstretched composite fibers in which low melting point components (B) made of a resin composition containing an amorphous resin (b) having a transition point (Tg) are bonded to each other; According to the production method of the present invention, the step of heat-stretching at a temperature not lower than the Tg of the resin (a) and not higher than the melting point and not higher than the Tg of the amorphous resin (b) is efficiently produced. be able to.
Furthermore, in the process of melt spinning the above-mentioned composite fiber, the high melting point component (A) and the low melting point component (B) can be joined substantially radially from the center of the fiber toward the fiber surface in the radial cross section of the composite fiber. Of a splittable concavo-convex composite fiber to be spun by adjusting the melt viscosity of the high-melting component (A) and the melt viscosity of the low-melting component (B) in the spinning head using a spinning device equipped with a flexible spinning head It can be a method.

(Melt spinning process)
In the production method of the present invention, the step of melt spinning the splittable concavo-convex composite fiber may be a known method conventionally used in the production of splittable composite fibers. For example, by using the above-mentioned low melting point component and high melting point component, and melt spinning at a spinning temperature of about 200 to 300 ° C. with a composite spinning apparatus equipped with two extruders and a split fiber nozzle, a plurality of two components A composite fiber having a structure in which is bonded is obtained. The high melting point component / low melting point component cross-sectional area ratio in the splittable concavo-convex composite fiber thus obtained is usually selected in the range of 40/60 to 80/20.

In the step of melt spinning the above-mentioned composite fiber, in the radial cross section of the composite fiber, the high melting point component (A) and the low melting point component (B) can be joined substantially radially from the center of the fiber toward the fiber surface. In a method for producing a splittable concavo-convex composite fiber for spinning by adjusting a melt viscosity of a high-melting component (A) and a melt viscosity of a low-melting component (B) in a spinning head using a spinning device equipped with a head. The melt viscosity can be adjusted by the following method.
That is, the melt flow rate of the melt flow rate of the crystalline thermoplastic resin having a high melting point component _(A) (MFR A) and the polyolefin resin having a low melting point component (B) (a) (MFR B), taking into consideration appropriately By adjusting the set temperature of the melt spinning machine for each component and adjusting the balance between the melt viscosity of the high-melting component (A) and the melt viscosity of the low-melting component (B) at the time when it is discharged from the spinning nozzle, It is possible to intentionally change which of the high melting point component (A) and the low melting point component (B) is positioned at the center of the fiber cross section, or whether the two components are arranged radially evenly.

Cross-sectional pattern 1 of splittable composite unstretched fiber
FIGS. 2A and 2B show the case where the melt viscosity of the high melting point component (A) is higher than the melt viscosity of the low melting point component (B), specifically, the melt flow rate of the high melting point component (A). If (MFR _a) is lower than the low-melting component (B) melt flow rate (HDPE and cyclic polyolefin copolymer) (MFR _B), the low-melting component (B) occupies the central portion of the unstretched fiber cross section, From there, a composite unstretched fiber cross section is formed which spreads radially toward the outer periphery of the fiber. In this case, the low melting point component (B) is joined at the center and the outer periphery ratio is high, so that the spinnability tends to be deteriorated. It is difficult to convert. In addition, since the ratio of the low melting point component (B) in the volume in the fiber and the fiber surface area is relatively high, the cyclic olefin copolymer serving as the core of the unevenness development is also included in the entire fiber including the center of the fiber cross section. As a result, the unevenness after forming into a non-woven fabric becomes small.

Cross-sectional pattern 2 of splittable composite unstretched fiber
2 (c) and 2 (d) are unstretched fiber cross-sectional shapes formed when the melt viscosity of the high melting point component (A) and the melt viscosity of the low melting point component (B) are substantially equal, and each component is unstretched. A cross section is formed that is radially joined from the center of the cross section of the fiber.
When the joint ratio of the central part and the ratio of the outer peripheral part are equal, there is a tendency for good spinnability, which is preferable in terms of production stability. Both the high melting point component (A) and the low melting point component (B) are likely to be finer after the unevenness due to stretching. Moreover, since the volume of the low-melting-point component (B) and the fiber surface area are smaller than those of the cross-sectional pattern 1, the uneven core becomes dense, and the unevenness after forming into a nonwoven fabric is also slightly increased. The split fiber of polypropylene (PP) / high density polyethylene (HDPE) can be achieved by powerful water jet treatment. Therefore, the improvement effect of the division property can be cited as one of the characteristics.

Cross-sectional pattern 3 of splittable composite unstretched fiber
FIG. 2 (e) shows a case where the melt viscosity of the high melting point component (A) is lower than the melt viscosity of the low melting point component (B), contrary to the cross-sectional pattern 1 of the splittable composite unstretched fiber. The cross section of the drawn fiber is represented. That, in particular when the melt flow rate of the high melting point component (A) (MFR _A) is higher than the low-melting component (B) (HDPE and cyclic polyolefin copolymer) melt flow rate (MFR _B) of the high Melting | fusing point component (A) joins in the center part, and an outer periphery ratio is also large. The spinnability tends to be the best, and the fineness of the low melting point component (B) (unevenness manifesting component) can be reduced by stretching. In addition, a fine gap is formed at the interface between the A component and the B component, and a capillary phenomenon is easily exhibited. Even when the low melting point component (B) is divided and separated from the high melting point component (A), the V-groove formed by the high melting point component (A) exhibits a structure that easily exhibits water absorption (water retention).
Further, the high melting point component (A) occupies the center of the cross section of the unstretched fiber, and forms a cross section of the composite fiber that spreads radially from there to the outer periphery of the fiber. Since the volume of the low melting point component (B) and the fiber surface area are smaller than those of the cross-sectional patterns 1 and 2, the cyclic olefin copolymer serving as the core of the unevenness is more dense, and the unevenness after making into a nonwoven fabric is the largest. Tend.
Above, the low melting point component of spinnability and irregularities are formed a (B) from the viewpoint of dividing the fineness, the adjustment of the melt viscosity, melt flow rate of the crystalline thermoplastic resin having a high melting point component _(A) (MFR A ) and a melt flow rate of the polyolefin resin having a low melting point component (B) (a) (MFR B), so as to be MFR _a ≧ MFR _B, to adjust a melt flow rate (MFR) of the raw material of each component preferable. Also, from the relationship of the distribution density of the cyclic olefin copolymer that becomes the core of the unevenness, it is preferable that MFR _A ≧ MFR _B because the volume of the low melting point component (B) and the fiber surface area can be reduced. .

(Heat drawing process)
In the production method of the present invention, the unstretched composite fiber obtained in the melt spinning step is subjected to a heat stretching process. This heat stretching treatment is performed at a temperature not lower than the glass transition temperature (Tg) of the polyolefin resin (a) and not higher than the melting point, and not higher than Tg of the amorphous resin (b).
In the heat drawing step, a conventionally known heat drawing method, for example, contact heating drawing using a generally known metal heating roll or metal heating plate, or hot water, normal pressure to 0.2 MPa (gauge pressure). ) Heating fluid such as water vapor and hot air, high-pressure steam stretching, non-contact heating stretching using heat rays such as far-infrared rays, and a combination of these can be applied.
In applications where texture is required, such as paper diapers, the draw ratio is usually about 2 to 6 times, preferably 3 to 5 times, from the viewpoint of developing fiber strength. The single yarn fineness in the obtained splittable uneven composite (drawn) fiber is usually about 1 to 10 dtex, preferably 2 to 7 dtex. The splittable concavo-convex composite fiber can be split in accordance with the number of partition components in the fiber cross section, and can be made finer.

(Crimping)
In the present invention, the splittable concavo-convex composite drawn fiber thus obtained is usually crimped. There is no restriction | limiting in particular as this crimping method, The method conventionally used for the crimping process of the polyolefin-type composite stretched fiber can be used. For example, the splittable concavo-convex composite stretched fiber is subjected to mechanical crimping by a conventional method at a crimp number of about 10 to 18 pieces / 2.5 cm, preferably 12 to 16 pieces / 2.5 cm. Is obtained.
Also, by applying (attaching) an oil to the fiber in this step, the non-woven fabric characteristics after fiber and hot air fusion are high-order workability with respect to carding and the like, initial water permeability as a non-woven fabric, durable hydrophilicity, repellent properties. Various performances such as aqueous properties can be imparted.

(Cutting process)
The splittable concavo-convex composite stretched fiber is formed into concavo-convex nuclei due to the amorphous resin (b) of the low melting point component (B) by stretching, and is cut into 3 to 100 mm through a drying treatment as necessary. .

(Fineness refinement by splitting splittable uneven composite stretched fiber)
If the crimped splittable concavo-convex composite stretched fiber is desired to be further finer, it can be made finer by splitting the fiber, for example, by water jet treatment after making it into a nonwoven fabric.
Next, the nonwoven fabric of this invention is demonstrated.

[Nonwoven fabric]
The fiber obtained from the above-described splittable concavo-convex composite fiber of the present invention can be made into a non-woven fabric in which the concavo-convex shape is manifested (expressed) on the surface of the low melting point component (B) by heat treatment when forming the non-woven fabric. (Nonwoven fabric manufacturing method)
A nonwoven fabric can be manufactured by the following method, for example.
First, the crimped composite drawn fiber obtained by the above-described crimping process is usually cut into 15 to 80 mm, preferably 25 to 60 mm, in accordance with a conventional method, to obtain a splittable uneven composite fiber of short fibers. Subsequently, a nonwoven fabric is produced by a method selected from the production methods described later using the splittable uneven composite fiber of short fibers.
In addition, when the cyclic olefin copolymer (coc) having a high Tg is added to the low melting point component (B) polyolefin-based resin to form a concavo-convex fiber nonwoven fabric, the nonwoven fabric strength is 20% in the MD direction compared to the unadded product, CD In the direction, there is an entity that falls by 30%. In the present invention, the surface ratio of the adhesive component (low melting point component) is originally about 50% in terms of the nozzle design. As described above, the surface ratio of the adhesive component also changes depending on the resin viscosity, and the adhesive performance as an adhesive fiber is as follows. It goes down as follows.
(I) When the surface ratio of the adhesive component is about 60% (= estimated), the adhesive strength is reduced by 70 to 80% as compared with a concentric type (sheath core type) non-added product.
(ii) When the surface ratio of the adhesive component is about 50% (= estimated), the adhesive strength is reduced by 80 to 90% compared to the unadded core type product.
(iii) When the surface ratio of the adhesive component is about 40% (= estimated), it seems that there is almost no adhesive performance.
As described above, since the adhesive strength is low, when a heat-fused nonwoven fabric is used, it is preferably used by blending with concentric composite fibers (PP or PET / HDPE).

Nonwoven fabric production methods include a heat fusion method, a heat roll method, a spunlace method, a needle punch method, etc. In the present invention, it is advantageous to employ a heat fusion method, particularly a hot air fusion method. is there. When a nonwoven fabric is produced by this heat fusion method, particularly the hot air fusion method, irregular irregularities appear on the surface of the low melting point component (B) of the splittable irregular composite fiber simultaneously with the production of the nonwoven fabric, and the desired nonwoven fabric. This is because it can be easily obtained.
There is no restriction | limiting in particular as a manufacturing method of the nonwoven fabric by this hot-air melt | fusion method, The method conventionally used in manufacture of the nonwoven fabric by a hot-air melt | fusion process can be used. For example, after splitting concavo-convex composite fibers of short fibers obtained as described above are carded with a roller card machine to produce a web with a desired weight per unit area, by a hot air fusion method such as an air-through method, The said nonwoven fabric is obtained.
At this time, it is important that the hot air fusion is performed at a temperature equal to or higher than the melting point of the polyolefin resin (a). In particular, the glass transition of the amorphous resin (b) is equal to or higher than the melting point of the polyolefin resin (a). It is more preferable to carry out at a temperature below the point (Tg).

  The nonwoven fabric obtained as described above was formed at the interface between the high melting point component (A) and the low melting point component (B) in the uneven shape formed on the fiber surface by hot air fusion, and in the undivided portion. A fine gap causes a structure in which capillary action is likely to occur, and the nonwoven fabric has high water absorption (water retention). Even when the low melting point component (B) is divided and separated from the high melting point component (A), the effect can be further exhibited by the V-groove formed by the high melting point component (A).

[Consideration of the mechanism of unevenness]
It is considered that the amorphous resin (b) exists in a rod state stretched in the polyolefin resin (a) by spinning. During stretching, the presence or absence of unevenness depending on the relationship between the glass transition point (Tg) and melting point (Tm) of the polyolefin resin (a), the glass transition point (Tg) of the amorphous resin (b), and the stretching temperature. Is determined and can be patterned as follows.

(I) Concavity and convexity expression pattern (1): Glass transition point (Tg) of amorphous resin (b)> Melting point (Tm) of polyolefin resin (a)> When stretching temperature Glass of amorphous resin (b) Since the transition point (Tg) is higher than the stretching temperature, the rod-shaped amorphous resin (b) is not easily stretched, breaks by weak stretching, and has a larger diameter (uneven core) than the stretched portion of the polyolefin resin (a). ). On the other hand, since the polyolefin resin (a) is crystalline and easily stretched, it continues to be stretched as it is. As a result, it is considered that relatively large amorphous resin (b) is intermittently present in the drawn yarn. And when making into a non-woven fabric, the amorphous resin (b) is agglomerated by a surface tension from a shredded shape to become a round shape by being heated at the time of hot-air fusion, and it is considered that irregularities appear at that time. .

(Ii) Concavity and convexity expression pattern (2): Melting point (Tm) of polyolefin resin (a)> Glass transition point (Tg) of amorphous resin (b)> When stretching temperature Glass of amorphous resin (b) Since the transition point (Tg) and the stretching temperature are close, the rod-shaped amorphous resin (b) is in an easily stretchable state, and the amorphous resin (b) continues to stretch to a certain extent and then stretches to a limit magnification that can be stretched. It is considered that the ruptured lump (uneven core) is smaller than the above (i), and as a result, the uneven shape after hot-air fusion is also reduced.

(Iii) Concavity and convexity expression pattern (3): Melting point (Tm) of polyolefin resin (a)> Stretching temperature> When glass transition point (Tg) of amorphous resin (b) Glass of amorphous resin (b) Since the transition point (Tg) is lower than the stretching temperature, the amorphous resin (b) is reduced in rigidity and viscosity at the stretching temperature, and is smoothly stretched together with the polyolefin resin (a). Since the resin (b) lump is not formed, it is considered that unevenness does not appear.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples. In the following examples and comparative examples, the cooling conditions in the common spinning process and the temperature conditions of the stretching roller are collectively shown.

(1) Cooling conditions in the spinning process In the following examples and comparative examples, the spinning fibers in the spinning process of the splittable uneven composite fiber were cooled by a cross wind cooling device using a cooling wind speed of 3.5 m / sec and a wind temperature of 15 C., and the cycle was 30 Hz.
(2) Stretching roller temperature conditions The first to fourth stretching rollers that are capable of controlling the respective surface temperatures by focusing the splittable composite unstretched fibers to a predetermined total fineness, the first roller temperature of 80 ° C., the second The roller temperature was 100 ° C., the third roller temperature was 85 ° C., the fourth roller temperature was 75 ° C., and the temperature between the rollers as the stretching temperature was 98 ° C., and stretching was performed 4 times and 2 times.

Evaluation of the uneven state on the fiber surface was performed as follows.
(i) Evaluation of unstretched fiber of splittable concavo-convex composite fiber and concavo-convex state of stretched fiber Take SEM photographs of unstretched fiber and side surfaces of stretched fiber, visually observe the photographs, and qualitatively according to the following criteria Evaluation was performed.
○: When the boundary between the high melting point component and the low melting point component of the fiber is clear and a clear concave or convex portion is formed in the low melting point component Δ: The boundary between the high melting point component and the low melting point component of the fiber is formed, When the uneven shape is slightly observed in the low melting point component x: When the boundary between the high melting point component and the low melting point component of the fiber is unclear, and the uneven surface is not recognized, the surface is smooth
(ii) Evaluation of uneven state of nonwoven fabric produced by hot-air fusion treatment of splittable concavo-convex composite fiber A SEM photograph of a nonwoven fabric produced by hot-air fusion treatment of splittable concavo-convex composite fiber was taken, and the photograph Visual observation was performed and qualitative evaluation was performed according to the following criteria.
A: When a large convex part is formed on the low melting point component side of the fiber and a concave part is formed so that a cavity is opened between the convex parts. ○: Only an intermittent convex part is formed on the low melting point component side of the fiber. When X: When the low melting point component of the fiber has no protrusions or recesses and only streaky protrusions exist

Example 1
(1) Production of splittable concavo-convex composite fiber As a high melting point component (A) material, homopolypropylene [manufactured by Prime Polymer Co., Ltd., trade name “Y6005GM”, MFR (230 ° C., 2.16 kg) = 60 g / 10 min, melting point: 161 ° C.] As a low melting point component (B) material, high-density polyethylene [manufactured by Keiyo Polyethylene Co., Ltd., trade name “S6932”, MFR (190 ° C., 2.16 kg) = 20 g / 10 min, melting point: 130 ° C., Tg: -120 ° C] and cyclic olefin copolymer [manufactured by Polyplastics, registered trademark “TOPAS 5013”, Tg = 134 ° C., melt volume rate (MVR) at 260 ° C./2.16 kg = 48 ml / 10 min] Using a resin composition containing 90:10, an 8-split composite fiber having 2 single-screw extruders and 600 holes with a hole diameter of 0.4 mm Spinning at a spinning temperature of 260 ° C., the above-mentioned cooling conditions, and a take-up speed of 300 m / min by a composite spinning device equipped with a nozzle for high-melting component (A) and low-melting component (B) are divided into 4 parts each. A splittable concavo-convex composite unstretched fiber having a single yarn fineness of 8.1 dtex having a cross-sectional shape shown in FIG. Table 1 summarizes the raw material composition, spinning conditions, and the like.

(2) Production of splittable concavo-convex composite stretched fiber The splittable concavo-convex composite unstretched fiber obtained in (1) above is stretched under the conditions of a stretching temperature of 98 ° C between rollers of the above-mentioned stretching roller temperature conditions. A splittable concavo-convex composite fiber having a draw ratio of 4 and a single yarn fineness of 2.2 dTex was produced.
(3) Production of splittable concavo-convex composite fiber of short fibers The crimpable concavo-convex composite fiber obtained in (2) above was subjected to mechanical crimping. Then, the splittable uneven | corrugated composite fiber of a short fiber was produced by cutting to 50 mm length with a rotary cutter.

(4) Fabrication of nonwoven fabric Using the short-fiber splittable concavo-convex composite fiber obtained in (3) above, carded at a speed of 20 m / min with a roller card machine having a width of 360 mm, and a web having a basis weight of 10 g / m ² Were laminated in three layers to obtain a web having a basis weight of 30 g / m ² . Next, this web is placed on a wire mesh belt having a width of 350 mm and a speed of 5 m / min, and the low melting point component (B) is heated by a hot air fusion method in which hot air having a wind temperature of 135 ° C. and a wind speed of 2.7 m / sec is blown for 5 seconds. A hot-air fused nonwoven fabric having irregular irregularities on the surface was produced.
FIG. 3 (a) shows a scanning electron microscope (SEM) photograph of the splittable uneven composite unstretched fiber, FIG. 3 (b) shows an SEM photograph of the splittable uneven composite fiber, and FIG. 3 (c) shows a hot-air fused nonwoven fabric. The SEM photograph of the splittable uneven | corrugated composite fiber which comprises is shown.
As can be seen from FIGS. 3 (a) to 3 (c), no irregularities are observed on the surface of the low melting point component (B) of the splittable uneven composite unstretched fiber (judgment: x). Slight irregularities are observed on the surface of the low melting point component (B) (judgment: Δ). Moreover, only the intermittent convex part was formed in the low melting-point component (B) of the splittable uneven | corrugated composite fiber which comprises a hot-air melt | fusion nonwoven fabric (determination: (circle)). These irregularities are summarized in Table 1.

Example 2
In Example 1 (1), except that the cyclic olefin copolymer was changed to “TOPAS 6013” (Tg = 138 ° C., MVR at 260 ° C./2.16 kg = 14 ml / 10 minutes), the same as in Example 1, A splittable uneven composite unstretched fiber was obtained. Although 4 times stretching was tried, the same operation as Example 1 was performed except that it was able to stretch only up to 2 times and the single yarn fineness was 4.4 dtex. The cross section of the splittable concavo-convex composite non-fiber approximated that shown in FIG.
FIG. 4A shows an SEM photograph of the splittable uneven composite stretched fiber, and FIG. 4B shows an SEM photograph of the splittable uneven composite fiber constituting the hot-air fused nonwoven fabric.
As can be seen from FIGS. 4 (a) and 4 (b), large concave portions are recognized on the surface of the splittable concave / convex composite stretched fibers (judgment: ◯), and the splittable concave / convex composite fibers constituting the hot-air fused nonwoven fabric. A large convex portion was formed on the surface, and a concave portion was formed so as to open a cavity in the fiber (judgment: A). This is because the melt volume rate (MVR) (260 ° C./2.16 kg) of the cyclic olefin copolymer is as low as 14 (ml / 10 minutes) compared with the cyclic olefin copolymer used in Example 1, 10% by mass. In this composition, it is considered that the mixing and dispersion with the high-density polyethylene is not necessarily uniform, the stretching ratio is not increased, and the peeling force is partially applied to the low melting point component (B) due to the high stretching stress.

Example 3
In Example 2, homopolypropylene [manufactured by Prime Polymer Co., Ltd., trade name “S119”, MFR (230 ° C., 2.16 kg) = 60 g / 10 min, melting point: 161 ° C.] was used as the high melting point component (A) material. , as a low-melting component (B) material, the same high density polyethylene as in example 2, the cyclic olefin copolymer and the mass ratio of 95: is except that the resin composition in a proportion of 5, similar to example 2 The operation was performed. Stretching could be 4 times. The cross section of the splittable concavo-convex composite unstretched fiber was close to that shown in FIG. Slight irregularities are observed on the surface of the low melting point component (B) of the splittable uneven composite stretched fiber (judgment: Δ), and the low melting point component (B) of the splittable uneven composite fiber constituting the hot-air fused nonwoven fabric is intermittent. Only the convex part was formed. (Judgment: ○).

Example 4
In Example 1 (1), as a high melting point component (A) material, homopolypropylene [manufactured by Prime Polymer Co., Ltd., trade name “S119”, MFR (230 ° C., 2.16 kg) = 60 g / 10 min, melting point: 161 ° C. ], The cyclic olefin copolymer was changed to “TOPAS 7010” (Tg = 110 ° C., MVR = 260 ml / 2.16 kg = 40 ml / 10 min) as the low melting point component (B) material, and other conditions were carried out In the same manner as in Example 1, a splittable uneven composite unstretched fiber was obtained.
It was possible to stretch 4 times. The cross section of the splittable concavo-convex composite unstretched fiber was close to that shown in FIG.
FIG. 5A shows an SEM photograph of the splittable uneven composite stretched fiber, and FIG. 5B shows an SEM photograph of the splittable uneven composite fiber constituting the hot-air fused nonwoven fabric.
Although slightly smaller than Example 1, slight unevenness was observed on the surface of the low melting point component (B) of the splittable uneven stretched composite fiber (judgment: Δ). Moreover, although only the intermittent convex part was formed in the low melting-point component (B) of the splittable uneven | corrugated composite fiber which comprises a hot-air melt | fusion nonwoven fabric, the unevenness | corrugation was small compared with Example 1 (judgment: (circle)). This is because, as shown in the above-described concavo-convex expression pattern (2), since the glass transition point (Tg) of the amorphous resin (b) and the stretching temperature are close, the core of the concavo-convex formed is reduced. It is believed that there is.

Example 5
In Example 3, the blending ratio of the cyclic polyolefin copolymer in the low-melting-point component (B) was 10% by mass, and “TOPAS 6013” used in Example 2 and “TOPAS 5013” used in Example 1 were each 5% by mass. Used one by one. Other than that was carried out similarly to Example 3, the division | segmentation uneven | corrugated composite fiber and the hot-air fusion | melting nonwoven fabric were obtained, and the uneven | corrugated state of the fiber surface was observed. The cross section of the splittable concavo-convex composite unstretched fiber was close to that shown in FIG. Slight irregularities are observed in the splittable concave / convex composite stretched fibers (judgment: Δ), and only intermittent convex portions are formed in the low melting point component (B) of the splittable concave / convex composite fibers constituting the hot-air fused nonwoven fabric. It was. (Judgment: ○).

Example 6
In the same manner as in Example 5, the blending ratio of the cyclic polyolefin copolymer in the low melting point component (B) was 10% by mass, and “TOPAS 6013” used in Example 2 and the cyclic olefin copolymer “TOPAS 8007” (Tg = 78 ° C.). , 260 ° C./2.16 kg MVR = 32 ml / 10 min) was used at 5 mass% each. Other than that was carried out similarly to Example 5, obtained the splittable uneven | corrugated composite fiber and the hot-air fusion nonwoven fabric, and observed the uneven | corrugated state of the fiber surface. The cross section of the splittable concavo-convex composite unstretched fiber was close to that shown in FIG. Slight irregularities are observed in the splittable concave / convex composite stretched fibers (judgment: Δ), and only intermittent convex portions are formed in the low melting point component (B) of the splittable concave / convex composite fibers constituting the hot-air fused nonwoven fabric. It was. (Judgment: ○).

Example 7
In order to equalize the area ratio of the high melting point component (A) and the low melting point component (B) in the fiber cross section, the high melting point component (B) is a homopolypropylene having a different MFR, that is, a product name of Prime Polymer Co., Ltd. “Y2005GP” (MFR = 20 g / 10 min, melting point: 161 ° C.) and “S119” (MFR 60 g / 10 min, melting point: 161 ° C.) manufactured by the same company are mixed at a ratio of 60% by mass / 40% by mass. The MFR was set to be equivalent to 31 g / 10 minutes, and splittable concavo-convex composite fibers and hot air fused fibers were obtained. Slight irregularities are observed in the splittable concave / convex composite stretched fibers (judgment: Δ), and only intermittent convex portions are formed in the low melting point component (B) of the splittable concave / convex composite fibers constituting the hot-air fused nonwoven fabric. It was. (Judgment: ○).
As shown in FIG. 2 (c), the cross section of the splittable concavo-convex composite unstretched fiber has a high melting point component (A) and a low melting point component (B). The area ratio was almost the same.

Example 8
As in Example 7, in order to make the area ratio of the high melting point component (A) and the low melting point component (B) in the fiber cross section equal, two types of homopolypropylenes having different MFRs in the high melting point component (B), that is, 30% by mass / 70% by mass of Prime Polymer Co., Ltd., trade name “Y2005GP” (MFR = 20 g / 10 min, melting point: 161 ° C.) and “S119” (MFR 60 g / 10 min, melting point: 161 ° C.) In the same manner as in Example 1 except that the target MFR was equivalent to 43 g / 10 min, and a splittable uneven composite fiber and hot-air fused fiber were obtained. As a result, slight unevenness was observed in the splittable uneven composite stretched fiber (judgment: Δ), and only intermittent convex portions were present in the low melting point component (B) of the splittable uneven composite fiber constituting the hot-air fused nonwoven fabric. Was formed. (Judgment: ○).
The cross section of the splittable concavo-convex composite unstretched fiber was substantially the same as that of Example 6, as shown in FIG.
In Examples 7 and 8, the MFR was adjusted to “equivalent” by using two types of homopolypropylene. In this case, the MFR of the blend obtained from the two types of MFR and mass% is as follows regarding the melt flow rate: Calculated by the equation
log (MFR Brent) = w ₁ log (MFR ₁ ) + w ₂ log (MFR ₂ ) +… + w _i log (MFR _i ) +… + w _n log (MFR _n )
Where w _i is the weight fraction of component i, MFR _i is the melt flow rate of component i, n is the total number of components in the blend, and w ₁ + w ₂ +… + w _i +… w _n = 1
It is.

Example 9
As a high melting point component (A), a homopolypropylene manufactured by Prime Polymer Co., Ltd. [trade name “Y2005GP”, MFR (230 ° C., 2.16 kg) = 20 g / 10 min] is 35% by mass, similarly [trade name “Y900GV”, 35% by mass of MFR (230 ° C., 2.16 kg) = 9 g / 10 min] and polypropylene modified with acid anhydride with carboxylic anhydride as a compatibilizer [MFR (230 ° C., 2.16 kg) = 524 g / 10 min, melting point 137 ° C.], 30% by mass, target MFR is equivalent to 40 g / 10 min, and the area ratio of the high melting point component (A) and the low melting point component (B) in the fiber cross section is equal. Was obtained in the same manner as in Example 1 to obtain a splittable uneven composite non-fiber. The cross section of the splittable concavo-convex composite unstretched fiber was similar to FIG.
The spinnable fineness of the obtained splittable uneven composite unstretched fiber was 12.2 dtex, and a splittable uneven composite fiber having a single yarn fineness of 3.3 dtex was obtained when the draw ratio was 4 times. Slight irregularities are observed in the splittable concave / convex composite stretched fibers (judgment: Δ), and only intermittent convex portions are formed in the low melting point component (B) of the splittable concave / convex composite fibers constituting the hot-air fused nonwoven fabric. It was. (Judgment: ○).
An SEM photograph of the obtained splittable uneven stretched composite fiber is shown in FIG. Moreover, the SEM photograph of the splittable concavo-convex composite fiber constituting the hot-air fused nonwoven fabric obtained in the same manner as in Example 1 is shown in FIG.

Example 10
Homopolypropylene (manufactured by Prime Polymer Co., Ltd., trade name “S119”, MFR (230 ° C., 2.16 kg) = 60 g / 10 min) is used as the high melting point component (A) material. , High density polyethylene [trade name “S6932” manufactured by Keiyo Polyethylene Co., Ltd., MFR (190 ° C., 2.16 kg) = 20 g / 10 min, melting point: 130 ° C., Tg: −120 ° C.] 60% by mass, cyclic olefin copolymer [Made of Polyplastics, registered trademark “TOPAS 5013”, Tg = 134 ° C., MVR at 260 ° C./2.16 kg = 48 ml / 10 min] 10% by mass, acid-modified with carboxylic anhydride used in Example 9 30% by mass of polypropylene [MFR (230 ° C., 2.16 kg) = 524 g / 10 min, melting point: 137 ° C.] added to the low melting point component (B), Example 1 In the same manner as to obtain a division of irregularities conjugate fiber of 2.2 dtex. A large concave portion is recognized in the splittable uneven composite stretched fiber (judgment: ◯), and a large convex portion is formed in the splittable concave-convex composite fiber constituting the hot-air fused nonwoven fabric, so that a cavity is opened in the fiber. A recess was formed (judgment: A).
An SEM photograph of the obtained splittable concavo-convex stretched composite fiber is shown in FIG. Moreover, the SEM photograph of the splittable uneven | corrugated composite fiber which comprises the hot air fusion | melting nonwoven fabric obtained by carrying out similarly to Example 1 is shown in FIG.7 (b).

Comparative Example 1
In Example 1, it carried out like Example 1 except not adding amorphous resin (b) (TOPAS, 5013) to a low melting point component. The surface of the drawn fiber was smooth and had no irregularities (judgment: x), and the fiber low-melting point component after hot-air fusion had no projections or depressions and only streaky projections (judgment: x). The cross section of the undrawn fiber was similar to that shown in FIG.
An SEM photograph of the obtained splittable concavo-convex stretched composite fiber is shown in FIG. Moreover, the SEM photograph of the splittable uneven | corrugated composite fiber which comprises the hot air fusion | melting nonwoven fabric obtained by carrying out similarly to Example 1 is shown in FIG.8 (b). The raw material composition, spinning conditions, etc. are summarized in Table 2.

Comparative Example 2
In Example 1, the amorphous resin (b) of the low melting point component was changed from (TOPAS, 5013) to (TOPAS, 8007, Tg = 78 ° C., MVR at 260 ° C./2.16 kg = 32 ml / 10 minutes). Except for the above, a 2.2 dtex splittable conjugate fiber was obtained in the same manner as in Example 1. The cross section of the undrawn fiber was similar to that shown in FIG. Further, the stretched composite fiber was smooth and had no unevenness (judgment: x), and the splittable composite fiber after hot-air fusion had no unevenness, and only streak-like protrusions were present (judgment: x).
An SEM photograph of the obtained splittable uneven stretched composite fiber is shown in FIG. Moreover, the SEM photograph of the splittable uneven | corrugated composite fiber which comprises the hot air fusion | melting nonwoven fabric obtained by carrying out similarly to Example 1 is shown in FIG.9 (b). The results are shown in Table 2.

Comparative Example 3
In Example 1, the low melting point component (B) amorphous resin (b) was changed from (TOPAS, 5013) to (TOPAS, 9506, Tg = 65 ° C., MVR at 260 ° C./2.16 kg = 5.5 ml / Except for changing to 10 minutes), a 2.2 dtex splittable conjugate fiber was obtained in the same manner as in Example 1. The cross section of the undrawn fiber was similar to that shown in FIG. In addition, the stretched conjugate fiber was smooth and had no irregularities (judgment: x), and the splittable conjugate fiber after hot-air fusion had no irregularities and only streak-like projections (judgment: x). The results are shown in Table 2.

Evaluation of splittable concavo-convex composite fiber (1) Dyeability of stretched composite fiber To see the difference in microstructure such as high melting point component (A), low melting point component (B), interface of each component of splittable concavo-convex stretched composite fiber Example 1, Example 4, Example 10, Comparative Example 1 and Comparative Example 2 showed differences in dyeability with dyes. Samples for dyeing are packed in a viscose rayon fiber around a splittable concavo-convex stretched composite fiber bundle as a sample in a 1.5 mm diameter hole perforated on a stainless steel plate 30 mm wide x 70 mm long and 1 mm thick And both sides of the stainless steel plate were prepared by cutting with a razor blade.
This was dyed for 1 minute in a dye bath at 20 ° C. of 5% by mass of Congo Red (manufactured by Nacalai Tesque).
The dyed sample was taken with a cross-sectional photograph of the fiber under an optical microscope to observe the dyeing situation, and the dyeability of the drawn composite fiber was determined according to the following criteria.
◎: Densely dyed with the dyeing solution, and when the two-component interface divided into eight on the fiber cross section cannot be discriminated at all. ○: Although it is thinner than the “◎”, it is dyed and the two-component interface on the fiber cross-section is discriminated. X: When the dye component is not dyed and the two-component interface of the fiber cross section can be clearly identified As a result of observing the dyeing condition of the drawn composite fiber by the above method, the low melting point component (B) is not Comparative Example 1 and Comparative Example 2 that do not contain a crystalline resin and do not exhibit unevenness after stretching were in a state where the two-component interface divided into eight in the fiber cross section without being dyed was clear (determination: X). On the other hand, in Examples 1 and 4, the dye entered the interface between the low melting point component and the high melting point component due to the effect of capillary action due to the unevenness, and the color tone was assimilated with the high melting point component side (determination: ◯).
In Example 10, large irregularities were observed on the surface of the drawn fiber, and some of the cross-sectional components were also divided so that they were dyed darkly, and the two-component interface divided into eight at the fiber cross-section could be completely discriminated. There was no (judgment: A). These are summarized in Table 3.

(2) Evaluation of siphoning performance Each of the splittable composite fibers of Example 1, Example 4, Example 10, Comparative Example 1 and Comparative Example 2 was heated at a temperature of 135 ° C. and a wind speed of 2.7 m / sec. A non-woven fabric was produced under the fusion conditions of a treatment time of 5 seconds. About the obtained nonwoven fabric, the siphoning performance was compared based on the birec method of JISL1907.
Specifically, the tip 20 mm in the length direction of the nonwoven fabric cut into a length of 200 mm × width of 25 mm was immersed in physiological saline, and the suction height (mm) after 10 minutes was measured.
The result of sucking height was higher as the uneven shape was larger. This is because the surface area of the fiber increases due to the appearance of irregularities, and the capillary phenomenon works. The results are shown in Table 3.

(3) Water absorption rate (water retention rate)
About the splittable composite fiber nonwoven fabric of Example 1, Example 4, Example 10, Comparative Example 1, and Comparative Example 2, the water absorption was measured based on the water absorption measurement of JIS L1907.
Specifically, a non-woven fabric cut out to 75 mm × 75 mm was immersed in physiological saline for 20 minutes, and then sandwiched between two dried filter papers, and pressurized with a roll at 25 mm / sec to calculate the water absorption rate.
In the water absorption rate (water retention rate), the same tendency as the result of the suction height was observed. The water absorption rate (water retention) is attributed to the fact that moisture is retained in the fine gaps generated by the irregularities in addition to the action of the capillary phenomenon. The results are shown in Table 3.

(4) Durability hydrophilicity evaluation About the splittable composite fiber nonwoven fabric of Example 1, Example 4, Example 10, Comparative Example 1, and Comparative Example 2, durable hydrophilicity was compared using the following one drop method.
<One drop method>
(I) A non-woven fabric cut into 100 mm × 100 mm is placed on a filter paper.
(Ii) Randomly mark 20 “•” marks on the nonwoven fabric with water repellent magic.
(Iii) A drop of physiological saline is dropped from a height of 10 mm to the location marked “•”.
(Iv) Count the places where water was absorbed within 5 seconds from the end of dropping.
(V) The nonwoven fabric is sandwiched between filter papers to remove moisture, and dropped again at the same place as the first mark “·”.
(Vi) Repeat steps (iii) to (v) five times to measure the water absorption location.
The following two points were used as the finishing oil adhered in the crimping process described above.
Condition 1: Initial water-permeable oil agent (Miyoshi Oil & Fats Co., Ltd., Soft Oil 120) adherence rate 0.5 mass% when used Condition 2: Durable hydrophilic oil agent (Takemoto Oil & Fat Co., Ltd. UN-594) Adhesion rate 0.5% by mass In use The initial water-permeable oil agent is an oil agent specialized in the initial water-permeation speed, and once it comes into contact with moisture, the oil agent flows down with water. Despite such performance, in Example 10, high hydrophilicity was maintained even in the second and subsequent drops. This is because the surface area of the fiber increased due to the large unevenness, and the capillary phenomenon worked strongly, the moisture was easily held in the fine gaps caused by the unevenness, and the oil agent did not easily enter the fine gaps. This is considered to be the cause. Although Example 1 and Example 4 did not reach Example 10, the same phenomenon acted by unevenness and durability hydrophilicity improved. However, Comparative Example 1 and Comparative Example 2 in which unevenness did not appear, all of the oil agent had flowed down by one drop according to the performance of the initial water-permeable oil agent.
The durable hydrophilic oil agent is an oil agent that is excellent in repeated dripping than the initial water-permeable oil agent. Even in this oil agent, durability hydrophilicity was improved in proportion to the size of the unevenness due to the same cause as the initial water-permeable oil agent.
Table 4 shows the evaluation of durable hydrophilicity with respect to the initial water-permeable oil agent, and Table 5 shows the evaluation of durable hydrophilicity with respect to the durable hydrophilic oil agent.

The splittable concavo-convex composite fiber of the present invention can be used as a fiber for a nonwoven fabric having a large performance (effect) for absorbing (holding) water.
Moreover, the manufacturing method of the splittable uneven composite fiber of the present invention can be used as an effective manufacturing method of the splittable uneven composite fiber.
Possible uses for splittable uneven composite fibers include the use of mixed cotton of the splittable uneven composite fibers and other fibers, and the surface material of paper diapers and napkins, and the surface material is expected to absorb water (water retention). In this case, it is possible to use the second sheet. That is, recent paper diapers have an absorbent body / second sheet / top sheet structure, and the purpose of the second sheet is to absorb urine more quickly and move it to the absorbent body. Expression of the function of the splittable concavo-convex composite fiber of the present invention having (water retention) is expected. It is also expected to improve the texture by dividing finer and use it for the top sheet.
In addition, as a single use application of the splittable concavo-convex composite fiber of the present invention, it is conceivable that the split fineness is reduced by a water jet (WJ) treatment to be applied to a flooring wiper.
Since the flooring wiper has a drying step after WJ treatment, it is possible to make the unevenness more prominent in this drying heat treatment, and because the adhesive performance is reduced, it becomes possible to secure free fibers of the nonwoven fabric, Products with high wiper performance (effect of entwining hair and solid waste “breadcrumbs”) can be expected.

Claims (12)

A high melting point component (A) comprising a crystalline thermoplastic resin;
The content ratio of the polyolefin resin (a) and the amorphous resin (b), which is a cyclic olefin copolymer and / or polycarbonate, to the polyolefin resin (a) and the amorphous resin (b) is 97: 3-85: see contains 15 ratio, and a low melting point glass transition point of the polyolefin resin (a) (Tg) is made of a low resin composition than the glass transition point (Tg) of the amorphous resin (b) A composite drawn fiber comprising component (B),
The composite stretched fiber has a cross-sectional shape in which the high melting point component (A) and the low melting point component (B) are joined to each other, and the fiber surface portion composed of the low melting point component (B) is the low melting point component (B). A splittable concavo-convex composite stretched fiber, characterized in that it has concave and convex portions along the fiber axis direction, and the convex portions are mainly formed of a mass of an amorphous resin (b) .   The splittable concavo-convex composite stretched fiber according to claim 1, wherein a glass transition point (Tg) of the amorphous resin (b) is higher than a melting point of the polyolefin resin (a).   The splittable unevenness according to claim 1 or 2, wherein the high melting point component (A) and the low melting point component (B) are joined substantially radially from the fiber central portion toward the fiber surface in the radial cross section of the composite fiber. Composite drawn fiber.   The crystalline thermoplastic resin of the high melting point component (A) is crystalline polypropylene or polyethylene terephthalate, and the polyolefin resin (a) of the low melting point component (B) is high density polyethylene. The splittable uneven composite stretched fiber described in 1.   The splittable concavo-convex composite stretched fiber according to any one of claims 1 to 4, wherein the amorphous resin (b) is a cyclic olefin copolymer.   High melting point component (A) containing crystalline thermoplastic resin, polyolefin resin (a) having a melting point lower than the melting point of crystalline thermoplastic resin of high melting point component (A), cyclic olefin copolymer and / or polycarbonate The amorphous resin (b) is a low resin composition comprising a polyolefin resin (a) and an amorphous resin (b) in a mass ratio of 97: 3 to 85:15. A step of melt-spinning the unstretched composite fiber in which the melting point components (B) are joined to each other; the unstretched composite fiber is at least Tg of the polyolefin resin (a) and at a temperature lower than the melting point; a process for heat-stretching at a temperature lower than the Tg of b).   In the step of melt spinning the above-mentioned composite fiber, in the radial cross section of the composite fiber, the high melting point component (A) and the low melting point component (B) can be joined substantially radially from the center of the fiber toward the fiber surface. The splitting unevenness according to claim 6, wherein spinning is performed by using a spinning device having a head part and adjusting the melt viscosity of the high melting point component (A) and the melt viscosity of the low melting point component (B) in the spinning head part. A method for producing a composite drawn fiber. The adjustment of the melt viscosity, the melt flow rate (MFR _B) of the melt flow rate of the crystalline thermoplastic resin having a high melting point component _(A) (MFR A) and the polyolefin resin having a low melting point component (B) (a) The manufacturing method of the splittable uneven | corrugated composite stretched fiber according to claim 7, wherein MFR _A ≥ MFR _B. A heat-bonding nonwoven fabric comprising a splittable concavo-convex composite stretched fiber that satisfies the following conditions and conditions.
The splittable concavo-convex composite stretched fiber comprises a high melting point component (A) containing a crystalline thermoplastic resin, a polyolefin resin (a), and an amorphous resin (b) that is a cyclic olefin copolymer and / or polycarbonate. The content ratio of the polyolefin resin (a) and the amorphous resin (b) is 97: 3 to 85:15 by mass ratio, and the glass transition point (Tg) of the polyolefin resin (a) is amorphous. A composite drawn fiber comprising a low melting point component (B) made of a resin composition lower than the glass transition point (Tg) of the resin (b), the composite drawn fiber comprising a high melting point component (A) and a low melting point sectional shape of the component (B) are bonded to each other, across the direction of fiber axis of the fiber surface portion comprising a low-melting component (B) is low-melting component (B), which caused a the concave portion and the convex portion The convex part is mainly formed by a mass of amorphous resin (b). It is.   The heat according to claim 9, wherein the crystalline thermoplastic resin of the high melting point component (A) is crystalline polypropylene or polyethylene terephthalate, and the polyolefin resin (a) of the low melting point component (B) is high density polyethylene. Fusion nonwoven fabric.   The heat-bonded nonwoven fabric according to claim 9 or 10, wherein the amorphous resin (b) is a cyclic olefin copolymer. The heat-bonded nonwoven fabric according to any one of claims 9 to 11 is at a temperature lower than the melting point of the high-melting-point component (A) containing a crystalline thermoplastic resin, and is equal to or higher than the melting point of the polyolefin resin (a). A method for producing a heat-sealed nonwoven fabric, characterized in that it is produced by hot air fusion at a temperature.