KR20050065601A - Nonwoven fabric made of core/sheath type composite fiber and process for producing the same - Google Patents

Abstract

A nonwoven fabric comprising core/sheath type long composite fibers as constituent fibers. The core comprises a polyester and the sheath comprises polyethylene. The polyethylene constituting the sheath preferably is a mixture of a first polyethylene obtained with a metallocene polymerization catalyst with a second polyethylene obtained with a Ziegler-Natta polymerization catalyst. The cross-sectional shape of the core does not substantially change in the axial direction of the fiber and the core has an even diameter. On the other hand, the thickness of the sheath is uneven in the axial and peripheral directions of the fiber and varies irregularly. The sheath hence has irregular recesses and protrusions. Consequently, the nonwoven fabric made of the core/sheath type long composite fibers is rich in flexibility.

Description

Non-woven fabric composed of core sheath-type composite fiber and its manufacturing method {NONWOVEN FABRIC MADE OF CORE / SHEATH TYPE COMPOSITE FIBER AND PROCESS FOR PRODUCING THE SAME}

The present invention relates to a nonwoven fabric having a special sheath-core type composite fiber as a constituent fiber, excellent in flexibility, and excellent in adhesiveness by heating, and a method for producing the same.

Background Art Conventionally, nonwoven fabrics having a core sheath composite fiber as a constituent fiber have been known. In particular, a nonwoven fabric composed of a core sheath composite long fiber composed of a polyester core portion and a sheath portion made of polyethylene has been known as an adhesive nonwoven fabric by heating [Japanese Patent Laid-Open No. 8-14069 (No. 1 page, claim 1). That is, since the adhesive nonwoven fabric by heating is made of a polyester having a deep melting point and a deep core made of polyethylene having a low melting point, the nonwoven fabric and other substrates are laminated to be heated and desired. Pressing by this means that only the first polyethylene is softened or melted and thermally bonded to the other substrate.

1 is a side view (micrograph) showing an example of a myocardial composite fiber in the present invention,

2 is a side view (micrograph) showing another example of the myocardial composite fiber in the present invention.

3 is a side view (micrograph) showing another example of the myocardial composite fiber in the present invention,

Figure 4 is an enlarged view (electron micrograph) of the long fiber nonwoven surface obtained by the method according to Example 2 below,

5 is an enlarged view (electron micrograph) of a long fiber nonwoven surface obtained by the method according to Example 3 below;

6 is an enlarged view (electron micrograph) of a long fiber nonwoven surface obtained by the method according to Example 4,

7 is an enlarged view (electron micrograph) of a long fiber nonwoven surface obtained by the method according to Example 5 below, and

Fig. 8 is a cross-sectional view (micrograph) showing an example of the heart sheath composite fiber of the present invention.

The present invention carried out a study to lower the melting point of polyethylene in order to improve the thermal adhesion of the adhesive nonwoven fabric by the above heating. In the course of such a study, the inventors found that, by using polyethylene as a specific material, it is possible to obtain a different form from the conventional typical myocardial composite long fibers. That is, it was found that a composite filament having irregular irregularities on the surface (which becomes the surface of the sheath) of the deep sheath type long filament can be obtained. In addition, it has also been found that such a composite filament is not constant in fiber diameter, has a thin portion and a thick portion, and has high flexibility due to the presence of the thin portion. Therefore, nonwoven fabrics comprising such composite long fibers as constituent fibers will also have high flexibility. Based on the above findings, the present invention is to provide a nonwoven fabric having excellent flexibility. And in order to solve the said subject, the following structures are employ | adopted.

That is, in the present invention, the core portion is polyester, the core portion is made of polyethylene, the cross-sectional shape of the core portion does not substantially change along the fiber axis direction, and the thickness of the edge portion is uneven along the fiber axis direction and the fiber circumferential direction, The present invention relates to a nonwoven fabric characterized in that randomly varying heart-shaped composite fibers are used as constituent fibers.

Best Mode for Carrying Out the Invention

The nonwoven fabric which concerns on this invention makes a specific core sheath type composite fiber a component fiber. The core sheath composite fibers may be either short fibers or long fibers, but in the present invention, it is preferable to obtain a nonwoven fabric by a spunbond method, so long fibers are preferred. The core sheath type composite fiber has a core part polyester, and the super part is comprised from polyethylene. Since the compatibility or affinity of polyester and polyethylene is not appropriately appropriate, a special heart sheath composite fiber can be obtained. Therefore, when a polypropylene or the like having excellent compatibility or affinity with polyethylene is used as the core portion, it is difficult to obtain a special sheath type composite fiber. In addition, even in the case of using polyamide having poor compatibility or affinity with polyethylene, etc., in addition to polyester, it is difficult to obtain a special heart-shaped composite fiber.

The cross-sectional shape of the core portion does not substantially change along the fiber axis direction as in the prior art. Typically, the core is preferably circular in shape no matter what cross section it takes. In addition, as polyester which comprises a core part, what is marketed and used especially for fiber especially in the polyethylene terephthalate currently marketed or industrially used may be sufficient. Specifically, it is preferable to use polyethylene terephthalate having an intrinsic viscosity of 0.50 to 1.20.

The surface of the sheath type composite fiber, that is, the surface of the sheath, is irregular irregularities. The irregular irregularities are caused by the thickness of the initial portion being nonuniform along the fiber axis direction and the fiber circumferential direction, and also randomly changing. About the thickness of a sheath part here, the thickness is set to 0 also about the part which a sheath part does not exist, ie, the part to which the core part is exposed. Therefore, the fiber diameter of the core-sheath type composite fibers are randomized to the diameter of the core in the range of φ ₀ through φ _1, along the fiber axis when the fiber diameter of the portion to φ _0, and the thickness of the sheath is a maximum to the φ ₁ It is changing. Also, if the radius of the core to the (φ _0/2), and the fiber radius of the portion of the thickness of the sheath is made maximum by (φ _1/2), along the fiber circumferentially fiber radius of core-sheath type conjugated fibers (φ _0/2) to (to random changes in the range of φ _1/2). In addition, although the case where the cross section of the core part and the poncho composite fiber was circular was demonstrated, these cross sections may not be circular. When the cross section of a core part and a sheath-type composite fiber is non-circular, it is good to interpret that the diameter of a core part and the fiber diameter of a sheath-type composite fiber are virtual or fiber diameter according to the said cross-sectional area.

It is preferable to use the mixture of the 1st polyethylene with good spinnability and the 2nd polyethylene with poor spineability as the polyethylene which comprises a sheath part. If only the first polyethylene having good fineness is used, irregular irregularities hardly appear on the surface of the sheath. That is, it is easy to become the same shape as the typical cardiac type composite fiber which has no unevenness | corrugation on the surface. In addition, when only the second polyethylene having poor sharpness is used, it is difficult to obtain a myocardial composite fiber by melt spinning. It is preferable that the mixing ratio of a 1st polyethylene and a 2nd polyethylene is 1st polyethylene: 2nd polyethylene = 30-70: 70-30 (weight%). As the first polyethylene, it is most preferable to use polyethylene obtained by a metallocene polymerization catalyst. This is because the polyethylene has a low melting point and is excellent in sharpness. As the second polyethylene, polyethylene generally used industrially, that is, polyethylene obtained by a Ziegler-Natta based polymerization catalyst can be used. Among these, low-density polyethylene is poor, and low-density polyethylene of low melting point, especially low-density polyethylene with a density of 0.910 to 0.925 is preferable.

The weight ratio of the core portion to the core portion is preferably 20 to 300 parts by weight based on 100 parts by weight of the core portion. In the present invention, since the thickness of the sheath is uneven along the fiber axis direction and the fiber circumferential direction and changes randomly, the weight ratio means the weight ratio in the whole of the sheath type composite fiber. If the sheath portion is less than 20 parts by weight, it is difficult to obtain sufficient adhesive strength when the sheath portion is used as a heat bonding component when bonding the sheath by heating. When the sheath portion exceeds 300 parts by weight, the amount of the core portion is relatively decreased, the diameter of the core portion is decreased, and the fiber strength at the defect portion of the sheath, i.e., the portion where the entire circumference of the core portion is exposed, decreases.

It is preferable that the fineness of the cardiac composite fiber in this invention is about 1.0 dTex-10 dTex. Since the fineness of the cardiac composite fiber in the present invention is nonuniform along the fiber axis direction and changes randomly, the fineness here refers to the average fineness of the whole cardiac composite fiber.

Specific examples of the shape of the heart sheath composite fiber in the present invention are shown in Figs. Two parallel straight lines have shown the side surface of a core part. Thus, the core is such that its cross-sectional shape does not change along the fiber axis direction. And the bulging like the hump above or below the said two parallel lines has shown the beginning part. As is apparent from this figure, the thickness of the sheath is non-uniform and varies randomly along the fiber axis direction and the fiber circumferential direction. 8 shows the specific example of the cross-sectional shape of the heart sheath composite fiber in this invention, and also it turns out that the thickness of a sheath part is nonuniform and changes randomly along the fiber circumferential direction.

Although the weight of the nonwoven fabric which uses the heart sheath composite fiber which consists of this invention as a component fiber is not restrict | limited, About 10 g / m <^2> -100g / m <^2> is preferable. The nonwoven fabric may obtain a bag-like article by laminating the nonwoven fabrics and adhering the end edges by heating. In addition, the nonwoven fabric may be a composite material by adhering to another material such as a synthetic resin film, knitted fabric, paper or other nonwoven fabric by adhesion by heating. That is, it is possible to soften or melt by applying heat and a desired pressure to the polyethylene constituting the initial portion of the heart sheath composite fiber, and thermally bond with the nonwoven fabrics or other materials. Particularly, in the case where the super-part of the heart sheath composite fiber of the present invention is a mixture of polyethylene and low-density polyethylene obtained by the metallocene-based polymerization catalyst, the melting point of the initial part is lowered, and thermal bonding is possible at a relatively low temperature. As another material, if a polyolefin-based material, in particular a polyolefin-based film, is used, compatibility with the first portion made of polyethylene is good, and high adhesion strength can be realized. In addition, even when thermally bonded with the polyethylene film, the polyethylene film also has the advantage that it is difficult to generate shrinkage, warpage or deformation under the influence of heat.

Next, the manufacturing method of the nonwoven fabric which uses the sheath sheath composite fiber which concerns on this invention as a component fiber is demonstrated. A representative method for producing a nonwoven fabric according to the present invention is to supply a polyethylene and a polyester in which a first polyethylene obtained by a metallocene polymerization catalyst and a second polyethylene obtained by a Ziegler-Natta polymerization catalyst are supplied to a deep sheath-type composite spinning orifice. Thus, the mixed polyethylene is disposed at the beginning, and the polyester is disposed at the core, and the sheath type long fibers obtained by melt spinning are accumulated. In other words, polyester is used as the resin constituting the core of the core sheath composite fiber, and the first polyethylene obtained by the metallocene polymerization catalyst and the second polyethylene obtained by the Ziegler-Natta polymerization catalyst are used as the resin constituting the core. This mixed polyethylene is used, and a long fiber nonwoven fabric is obtained by the spunbond method which employ | adopted the conventionally well-known deep-sea composite melt spinning method.

As a 1st polyethylene obtained by polyester, a metallocene type polymerization catalyst, and a 2nd polyethylene obtained by a Ziegler-Natta type | system | group polymerization catalyst, what was mentioned above is used. The first polyethylene and the second polyethylene are uniformly mixed in the above weight ratio and treated as polyethylene. The melt flow rate (MFR) of the polyethylene is preferably 16 g / 10 minutes to 21 g / 10 minutes. If it is in the said range, even if it spins at high speed, the edge part which is an irregular uneven surface is easy to be formed. In addition to the above ranges, it is possible to obtain an initial part having irregular irregularities on the surface by making the spinning speed more rapid when the value of MFR is large, while slowing the spinning speed when the value of MFR is small. However, in the case of the spinning speed generally employed, that is, the spinning speed of 3000 m / min to 4000 m / min, the MFR is preferably within the above range. Moreover, it is preferable that melting | fusing point of polyethylene is low, and especially 90 degreeC-about 110 degreeC are preferable. This is because the adhesion by heating at a relatively low temperature becomes possible.

Polyester and polyethylene are heated and melted, respectively, and polyester is placed at the core portion of the pleated complex spinning orifice installed in a plurality of spinnerets, while polyethylene is placed at the beginning. In addition, when melt spinning, a large number of heart-shaped composite long fibers having irregular irregularities on the surface are obtained. The present invention is characterized in that the myocardial composite long fibers having irregular irregularities on the surface can be obtained stably. That is, having irregular irregularities on the surface means that the fiber diameters differ along the fiber axis direction. When attempting to obtain such long fibers by melt spinning, conventionally, long fibers were cut at a portion having a small fiber diameter, and thus long fibers could not be stably obtained. That is, in the conventional melt spinning method, when unevenness is formed on the surface of the fiber, unevenness is immediately formed in a portion having good flowability of the resin immediately after spinning, and the stress is concentrated in the concave portion having a thin fiber diameter due to the good fluidity. Since it became easy to cut | disconnect in a part, long fiber could not be obtained stably. However, according to the present invention, it is possible to stably obtain long fibers having different fiber diameters along the fiber axis direction. This inventor interprets the said principle as follows. That is, when the composite melt spinning is carried out in the resin composition of the present invention, irregularities are not formed on the surface of the spinning fiber at the site where the flowability of the resin is good immediately after spinning, and the initial part is formed at the same time as or immediately after the core is solidified. It is interpreted that the polyethylene that is being bent causes irregular irregularities. In addition, the warping of the polyethylene is caused by the fact that the first polyethylene having good preparativeness and the second polyethylene having poor preliminary properties are mixed so that the first polyethylene contributes to the fiber formation together with the core, but the second polyethylene inhibits the fiber formation. I interpret it.

After obtaining the aquatic composite long fiber as described above, it is collected by collecting on a conveyor or the like to move it. Partial thermocompression bonding through embossing roll, etc., after integration, softens or melts the edges at the pressure-bonding site to bond the pleated composite long fibers to each other, thereby obtaining a nonwoven fabric having a desired tensile strength. It can be.

The nonwoven fabric which comprises the core sheath type | mold composite fiber which concerns on this invention as a component fiber is suitable for the use which adhere | attaches with another material by heating and obtains a composite material as mentioned above. It is also suitable for the purpose of laminating the nonwoven fabrics and bonding the edges thereof by heating to obtain a bag-like article. In addition to the above, it can be used for medical materials, sanitary materials, industrial materials, agricultural materials, living materials and the like in the same manner as the conventional nonwoven fabrics.

As described above, the nonwoven fabric according to the present invention is a constituent fiber of which the cross-sectional shape of the core portion does not substantially change along the fiber axis direction, the thickness of the initial portion is uneven along the fiber axis direction and the fiber circumferential direction, and also randomly. It is composed of a changing myocardial composite fiber. In other words, the core fiber composite fiber, which is a constituent fiber, becomes thinner or thicker in its fiber diameter along the fiber axis direction. The presence of the thin portion of the fiber diameter gives flexibility to the myocardial composite fiber. In addition, since the core portion has a uniform fiber diameter along the fiber axis direction, the tensile strength of the core sheath composite fiber is about the same as that of the conventional core sheath composite fiber. Therefore, the nonwoven fabric which consists of such a sheath type | mold composite fiber as a component fiber is excellent in tensile strength and excellent in flexibility.

In addition, since the nonwoven fabric according to the present invention is composed of a sheath-type composite fiber having irregular irregularities on its surface, it scatters light well. Therefore, the nonwoven fabric which concerns on this invention also has the outstanding effect to whiteness.

In the nonwoven fabric according to the present invention, the polyethylene constituting the initial part of the heart sheath composite fiber is a low-melting first polyethylene obtained by a metallocene-based polymerization catalyst and a low-melting point second polyethylene obtained by a Ziegler-Natta-based polymerization catalyst, in particular When employ | adopting a mixture with low density polyethylene, the adhesion by heating can be performed at low temperature, and it has the effect that thermocompression bonding at low temperature is attained.

Moreover, in the manufacturing method of the nonwoven fabric which concerns on this invention, the sheath part uses the polyethylene which consists of a mixture of the 1st polyethylene with a good sharpness, and the 2nd polyethylene with poor abrasion. When melt spinning using polyethylene in this way, the thickness of the sheath is randomly thickened or thinned when the sheath is formed by the second polyethylene having poor fineness. On the other hand, polyester is used for the core, and melt spinning can be performed uniformly as in the prior art. Therefore, the cross-sectional shape of the core portion does not substantially change along the fiber axis direction, and the sheath-type composite fibers in which the thickness of the sheath portion is uneven and randomly varying along the fiber axis direction and the fiber circumferential direction are obtained stably, Nonwoven fabrics composed of constituent fibers also have an effect that can be obtained stably and reasonably.

Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to an Example. The present invention is based on the finding that when a specific one is used as a polyethylene in the melt spinning method of a conventional myocardial composite long fiber, a composite long fiber having irregular irregularities on the surface of the myocardial composite long fiber, that is, the surface of the initial part, is stably obtained. Should be.

Each characteristic value in an Example was calculated | required as follows.

(1) intrinsic viscosity [η] of polyester; 0.5 g of a sample was melt | dissolved in 100 kPa of equal weight mixed solvents of a phenol and ethane tetrachloride, and it measured on the conditions of the temperature of 20 degreeC.

(2) melting point (° C.); It measured at the temperature increase rate of 20 degree-C / min using the differential scanning calorimeter DSC-7 type | mold by PerkinElmer.

(3) melt flow rate of polyethylene (g / 10 min); It measured on the conditions of 21.18 N load at the temperature of 190 degreeC according to the method of JISK6922.

(4) the flexibility of the nonwoven (g); It measured by the ductility E method steering wheel method (Handle-O-Meter) described in JISL1096.

(5) soft feeling of the nonwoven fabric; Five panelists evaluated the soft touch between the nonwoven fabric of an Example and a comparative example by the touch by hand as follows.

1: soft

2: slightly soft

3: hard

(6) Smoothness feeling of nonwoven fabric: Five panels of relative evaluation of the smoothness between the nonwoven fabrics of an Example and a comparative example were performed by the touch by hand as follows.

Large: Excellent smoothness

Medium: smooth

Cow: Less smooth

(7) tensile strength (N / 5cm width) of nonwoven fabric; According to the Synthetic Long Fiber Nonwoven Fabric Testing Method (JIS L 1906), a test piece having a width of 50 mm and a length of 200 mm was gripped using a Tensilon RTM-500 manufactured by Toyo Baldwin. It measured on the conditions of mm and the tensile speed of 100 mm / min, the average value of ten test pieces was calculated | required, and it was set as the tensile strength. In addition, about tensile strength, both the MD direction (machine direction) and CD direction (direction orthogonal to MD direction) of a nonwoven fabric were calculated | required.

(8) adhesive strength (N) by heating the nonwoven fabric; Two test pieces of 30 mm (CD direction) x 150 mm (MD direction) were overlapped with each other, and a place of 50 mm at the tip of the longitudinal direction (MD direction) was thermocompression-bonded by an adhesion tester by heating. Thermocompression was set at three types of temperatures of 100 ° C., 110 ° C. and 130 ° C., and the adhesion area was 10 mm (MD direction) × 30 mm (CD) at a surface pressure of 98 N / cm 2. Direction).

The adhesive strength by heating the thermocompression-bonding part was measured using TENSRON RTM-500 manufactured by Dongyang Baldwin Co., Ltd., according to the T peeling measurement method of JIS L 1089. It measured on condition, calculated | required the average value of 5 test pieces, and calculated it.

Example 1

Polyethylene terephthalate having an intrinsic viscosity [?] Of 0.70 and a melting point of 260 ° C was prepared. On the other hand, polyethylene with a melt flow rate of 18 g / 10 minutes, a density of 0.911 g / dl, and a melting point of 104 ° C. was prepared. The polyethylene was obtained by a metallocene polymerization catalyst. 60 parts by weight of the first polyethylene having a melt flow rate of 28 g / 10 minutes, a density of 0.906 g / dl, and a melting point of 97 ° C., and a Ziegler-Natta system polymerization catalyst. It is a mixture with 40 weight part of 2nd polyethylenes of melt flow rate 4g / 10min, density 0.918g / dl, melting | fusing point 106 degreeC.

Then, the polyester is placed at the core, the polyethylene is placed at the beginning, and both are equal parts by weight, and the feed is supplied to the pleated complex spinning orifice, and the melt spinning is carried out at a spinning temperature of 280 ° C and a spinning speed of 3800 m / min. Carried out. After melting and spinning, the thinner is thinned by the suction device and opened by the yarn group discharged from the suction device. Fineness 3.3 dTex) was integrated to obtain a nonwoven web. The nonwoven web was introduced into a thermal embossing apparatus consisting of an embossing roll (36% area area of the convex portion) having a surface temperature of 95 ° C. and a flat roll having a surface temperature of 95 ° C., and partially heated under conditions of a linear pressure of 294 N / cm. The pressure welding treatment was performed to obtain a long fiber nonwoven fabric having a weight of 50 g / m ² .

Example 2

Polyethylene terephthalate having an intrinsic viscosity [?] Of 0.70 and a melting point of 260 ° C was prepared. On the other hand, polyethylene with a melt flow rate of 21 g / 10 minutes, a density of 0.913 g / dl, and a melting point of 102 ° C. was prepared. The polyethylene had a melt flow rate of 28 g / 10 minutes obtained by the metallocene polymerization catalyst, a density of 0.906 g / dl, 60 parts by weight of the first polyethylene having a melting point of 97 ° C. and a melt flow rate of 14 g obtained by the Ziegler-Natta polymerization catalyst. 10 minutes, density 0.918 g / dl, and a mixture with 40 weight part of 2nd polyethylenes of melting | fusing point 106 degreeC.

Using the said polyester and polyethylene, the long fiber nonwoven fabric of 50 g / m <^2> in weight was obtained by the same method as Example 1.

Example 3

Polyethylene terephthalate having an intrinsic viscosity [?] Of 0.70 and a melting point of 260 ° C was prepared. On the other hand, polyethylene with a melt flow rate of 18 g / 10 minutes, a density of 0.913 g / dl, and a melting point of 104 ° C. was prepared. The polyethylene has a melt flow rate of 28 g / 10 minutes obtained by the metallocene polymerization catalyst, a density of 0.906 g / dl, 40 parts by weight of the first polyethylene having a melting point of 97 ° C. and a melt flow rate of 14 g obtained by the Ziegler-Natta polymerization catalyst. / 10 min, a mixture with 60 parts by weight of a second polyethylene having a density of 0.918 g / dl and a melting point of 106 캜.

Using the polyester and polyethylene, a long fiber nonwoven fabric having a weight of 50 g / m ² was obtained in the same manner as in Example 1.

Example 4

Polyethylene terephthalate having an intrinsic viscosity [?] Of 0.70 and a melting point of 260 ° C was prepared. On the other hand, polyethylene with a melt flow rate of 16 g / 10 minutes, a density of 0.910 g / dl, and a melting point of 103 ° C. was prepared. The polyethylene had a melt flow rate of 28 g / 10 minutes obtained by the metallocene polymerization catalyst, a density of 0.906 g / dl, 67 parts by weight of the first polyethylene having a melting point of 97 ° C., and a melt flow rate of 4 g obtained by the Ziegler-Natta polymerization catalyst. 10 minutes, density 0.918 g / dl, and a mixture with 33 weight part of 2nd polyethylenes of melting | fusing point 106 degreeC.

Using the said polyester and polyethylene, the long fiber nonwoven fabric of 50 g / m <^2> in weight was obtained by the same method as Example 1.

Example 5

Polyethylene terephthalate having an intrinsic viscosity [?] Of 0.70 and a melting point of 260 ° C was prepared. On the other hand, polyethylene with a melt flow rate of 22 g / 10 minutes, a density of 0.909 g / dl, and a melting point of 103 ° C. was prepared. The polyethylene was obtained by a metallocene polymerization catalyst. Melt flow rate 28 g / 10 min, density 0.906 g / kPa, 70 parts by weight of the first polyethylene having a melting point of 97 ° C. and melt flow rate 14 g / 10 min obtained by the Ziegler-Natta system polymerization catalyst, density 0.918 g / kPa, melting point 106 A mixture with 30 parts by weight of the second polyethylene at &lt; RTI ID = 0.0 &gt;

Using the said polyester and polyethylene, the long fiber nonwoven fabric of 50 g / m <^2> in weight was obtained by the same method as Example 1.

Comparative Example 1

Polyethylene terephthalate having an intrinsic viscosity [?] Of 0.70 and a melting point of 260 ° C was prepared. On the other hand, high density polyethylene with a melt flow rate of 25 g / 10 minutes, a density of 0.957 g / dl and a melting point of 130 ° C. was prepared. The high density polyethylene is obtained by a Ziegler-Natta type polymerization catalyst.

Using the said polyester and polyethylene, the long fiber nonwoven fabric of 50 g / m <^2> in weight was obtained by the same method as Example 1.

The flexibility, soft hand, smoothness, tensile strength and adhesive strength by heating of each long fiber nonwoven fabric obtained by the method according to Examples 1 to 5 and Comparative Example 1 were measured by the above-described method, and these results are shown in Table 1 Indicated.

An electron micrograph of the long fiber nonwoven surface obtained by the method according to Example 2 is also shown in FIG. 4, and an electron micrograph of the long fiber nonwoven surface obtained according to Example 3 is obtained in FIG. 5, according to Example 4. Electron micrographs of the long fiber nonwoven surface are shown in FIG. 6 and electron micrographs of the long fiber nonwoven surface obtained according to Example 5. FIG.

In the long fiber nonwoven fabric obtained by the method according to Examples 1 to 5, the long fibers constituting the nonwoven fabric had irregular irregularities along the fiber axis direction and the fiber circumference. On the other hand, in the long fiber nonwoven fabric obtained by the method according to Comparative Example 1, the long fiber surface constituting the nonwoven fabric was smooth along the fiber axis direction, and no irregularities existed. Due to the presence of such irregularities, the deep fiber portion and the thick portion are present in the deep sheath-type composite long fiber, and the long fiber itself is given flexibility by the presence of the thin fiber diameter. The nonwoven fabrics according to Examples 1 to 5 as constituent fibers were superior in flexibility and softness to the nonwoven fabrics according to Comparative Example 1. In addition, the light on the surface of the nonwoven fabric is easily scattered due to the presence of the irregularities, and the nonwoven fabrics according to Examples 1 to 5 had higher whiteness than those according to Comparative Example 1.

In general, since the first polyethylene obtained by the metallocene polymerization catalyst has a low melting point, the polyethylene in Examples 1 to 5 using the first polyethylene also has a low melting point. Therefore, even if the nonwoven fabrics of Examples 1 to 5 had a lower temperature of thermocompression bonding than the nonwoven fabrics of Comparative Example 1, good adhesive strength by heating was obtained. In addition, the core portion formed of polyester does not change the cross-sectional shape along the fiber axis direction as in the conventional one, and thus the tensile strength is maintained because the fiber diameter is substantially uniform, and the nonwoven fabric according to Examples 1 to 5 is compared with the conventional one. It had the same tensile strength as the nonwoven fabric concerning Example 1.

Claims (9)

The core portion is polyester, the sheath portion is made of polyethylene, and the cross-sectional shape of the core does not substantially change along the fiber axis direction, and the thickness of the candle portion is in the fiber axis direction and the fiber circumferential direction. Non-woven fabric characterized in that the constituent fibers of the sheath-type composite fibers are heterogeneous and randomly changed accordingly. The method of claim 1, The cardiac sheath composite fiber is a nonwoven fabric characterized in that it is long fiber. The method of claim 1, The polyethylene forming the first part is a nonwoven fabric characterized in that it is a mixture of a first polyethylene obtained by a metallocene polymerization catalyst and a second polyethylene obtained by a Ziegler-Natta polymerization catalyst. The method of claim 3, wherein The second polyethylene is a low density polyethylene. Cardiac composite fiber according to claim 1. A composite material characterized in that the nonwoven fabric according to claim 1 and the polyolefin-based film are adhered to each other by softening or melting the first part of the core sheath composite fiber. Polyethylene and polyester mixed with a first polyethylene obtained by a metallocene-based polymerization catalyst and a second polyethylene obtained by a Ziegler-Natta-based polymerization catalyst are fed to an eccentric composite spinning orifice, and the mixed polyethylene A method for producing a nonwoven fabric, wherein the polyester is placed in the core portion and the polyester is placed in the core portion, and the sheath type long fibers obtained by melt spinning are accumulated. The method of claim 7, wherein Melt flow rate (MFR) of polyethylene is 16 g / 10 minutes to 21 g / 10 minutes, characterized in that the manufacturing method of the nonwoven fabric. The method of claim 7, wherein The speed of melt spinning is 3000 m / min to 4000 m / min method for producing a nonwoven fabric.