JP3389927B2 - Polyethylene composite fiber and nonwoven fabric using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyethylene-based composite fiber and a non-woven fabric using the fiber. More specifically, the present invention relates to a polyethylene-based composite fiber characterized in that the processing temperature range can be widened during processing of the nonwoven fabric, the texture of the resulting nonwoven fabric is good, and the nonwoven fabric strength is high, and further, a nonwoven fabric using the same. The present invention relates to medical articles and hygiene articles using the nonwoven fabric.

[0002]

2. Description of the Related Art In the medical field, disposable surgical caps, sheets, surgical coverings, surgical gowns and the like made of non-woven fabrics are rapidly becoming popular. This is to cope with the movement to prevent nosocomial infections due to MRSA (methicillin-resistant staphylococcus aureus), hepatitis, HIV (acquired immunodeficiency syndrome) and the like. In addition, the use of disposable non-woven products that do not require cleaning can simplify nursing work without deteriorating the quality of nursing, and also help to solve the labor shortage, which is currently a serious social problem. Nonwoven fabrics used in the medical field include bacterial barrier properties, penetration resistance, water repellency,
Although it is required to be lint-free, since it is in direct contact with the human body and is a single-use disposable item, the feeling of wearing, strength, and cost are also important factors.

Polyethylene-based resins, polypropylene-based resins and polyester-based resins are generally used as raw material resins for fibers for non-woven fabrics, but non-woven fabrics used in the medical field are not exceptions. Nonwoven fabrics used in such a medical field are often sterilized by radiation. However, when a polypropylene resin is irradiated with radiation, the polymer chain is cut at the bonding site of the tertiary carbon atom, and the nonwoven fabric is Therefore, there is a problem in that the use is limited for applications such as radiation sterilization because the strength of the product is significantly reduced. Also, the strength of the polyester resin does not decrease due to radiation, but the cost of the raw material resin is higher than that of the polyolefin resin, and the strength of the resin does not break so that it follows the movement of the body, or it is not transparent. Therefore, when the non-woven fabric has a high basis weight, the non-woven fabric is hard to wear and has a poor feeling of wearing. Has become.

On the other hand, the polyethylene resin is a soft raw material resin, so that a flexible nonwoven fabric can be obtained. Since it does not have a tertiary carbon atom, it has the advantage that the strength of the non-woven fabric does not decrease due to radiation irradiation, and is therefore excellent as a non-woven fabric material for medical use. However, conventional polyethylene fibers composed of a single component are relatively unsuitable for hot air through-air processing, although it is relatively easy to emboss them with pressure rolls and calender them into non-woven fabrics when processing non-woven fabrics. The obtained nonwoven fabric lacks flexibility. In addition, in order to eliminate the above-mentioned drawbacks, for example, Table 6
A polyethylene-based composite having a high-density polyethylene as a first component and a copolymer of ethylene and an α-olefin (hereinafter abbreviated as linear low-density polyethylene (L-LDPE)) as a second component, such as 508892. Although fibers have been disclosed, when ordinary L-LDPE is used as the second component, the difference in melting point between the sheath and the core is small and it cannot be said that it is sufficiently suitable for through-air processing and the like. In addition, in order to obtain a difference in melting point between the first component and the second component, the second component is a linear low-density polyethylene resin having a relatively low density, such as very low den.
site polyethylene (VLDPE) and ultra low density polye
When polyethylene (ULDPE) is used, non-woven fabric processing is relatively easy, but the strength of the resulting non-woven fabric is significantly reduced.

[0005]

The object of the present invention is to solve the above-mentioned drawbacks of the prior art and to be suitably used for a pressure bonding method and a through-air bonding method, and which has a good texture and high strength. The object is to provide a polyethylene-based composite fiber that makes it possible to obtain, and a nonwoven fabric using the same.

[0006]

Means for Solving the Problems As a result of intensive investigations by the present inventors in order to solve the problems of the conventional polyethylene fibers, the low melting point component has a density of 0.850 to 0.930 g / c.
m ³ , Q value (weight average molecular weight Mw / number average molecular weight Mn)
The polyethylene resin (A) polymerized using a metallocene catalyst of 3.0 or less and the high melting point component have a density of 0.940 g / c.
It is a polyethylene-based composite fiber composed of a polyethylene resin (B) of m ³ or more, and it is known that the fiber can achieve the intended purpose in a fiber showing a DSC curve described later,
The present invention has been completed. The present invention has the following configurations.

(1) A composite fiber composed of two kinds of polyethylene resin components having different melting points, wherein the low melting point polyethylene resin component (A) is polymerized by using a metallocene catalyst and has a density of 0.850 to 0.930 g / cm 3. ³ , a component containing a polyethylene resin having a Q value (weight average molecular weight Mw / number average molecular weight Mn) of 3.0 or less, and the high melting point polyethylene resin component (B) is a polyethylene resin having a density of 0.940 g / cm ³ or more. The fiber has a DSC curve obtained by a measurement using a differential scanning calorimeter (DSC) (however, the temperature rising rate is 10 ° C.).
/ Min, and the vertical axis of the DSC chart (heat flow rate, unit: W
/ G) and the length of 2W / g is the same as the length of 50 ° C on the horizontal axis (temperature, unit: ° C))
In, the two polyethylene resin components (A) and (B) show endothermic curves having different endothermic peaks P ₁ and P ₂ , respectively, and the endothermic of the low melting point polyethylene resin component (A) from the baseline of the DSC curve. The length of a line segment extending vertically to the peak P ₁ is L _1, and a straight line parallel to the base line and passing through the midpoint between the base line and P ₁ intersects with the endothermic curve of the low melting point polyethylene resin component (A). When the length of the line segment is W, the relationship between L ₁ and W is L ₁ > 3W, which is a polyethylene-based composite fiber. (2) In the DSC curve of the polyethylene-based composite fiber according to the above item (1), the point closest to the baseline formed between the endothermic peaks P ₁ and P ₂ of the two polyethylene resin components is P _3, and when the length of a line extending perpendicularly from baseline to P ₃ was set to L _2, L ₁ and L ₂ of the relationship L _1>
A polyethylene-based composite fiber characterized by being 3 L ₂ . (3) A non-woven fabric using the polyethylene-based composite fiber according to the above (1) or (2). (4) A nonwoven fabric using the polyethylene-based composite fiber according to the above (1) or (2), which is obtained by a spunbond method. (5) The non-woven fabric according to item (3) or (4), wherein the fibers are heat-sealed by the through air processing method. (6) The non-woven fabric according to the above (3) or (4), wherein the fibers are heat-sealed by the poin bond processing method. (7) A medical article in which the nonwoven fabric according to any one of (3) to (6) is partially used. (8) A sanitary article partially using the nonwoven fabric according to any one of (3) to (6).

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
Generally, the melting point of the polyolefin resin is related to the density of the resin, and the lower the density of the resin, the lower the melting point, and the polyethylene resin is no exception. In the composite fiber, the larger the difference in melting point between the low-melting point component and the high-melting point component, the wider the processing temperature range and the easier the processing such as the through-air processing method and the thermocompression bonding method. Lowering the melting point is economical because the amount of heat that melts during processing is small.

However, a polyethylene resin having a low density generally has a large Q value (wide molecular weight distribution) and an increased amount of low molecular weight components, so that the melting start temperature is lowered, but the stickiness of the fiber surface and the strength of the nonwoven fabric are lowered. It becomes a problem. DSC measurement (JIS K7122) using a differential scanning calorimeter is known as the most general measurement method for analyzing the melting point, melting start temperature, composition ratio, etc. of a resin, and the peak of the endothermic curve obtained is known. The temperature corresponds to the melting point of the resin. Generally, a DSC curve of a fiber obtained by polymerizing with a Ziegler-Natta catalyst using a polyethylene resin having a low melting point and a low density as a low melting point component and a high density polyethylene resin as a high melting point component to form a composite fiber is as shown in FIG. The endothermic curve showing the low melting point component is extremely broad. When the density of the low melting point component is increased, the melting point of the resin is also increased, and as a result, the melting point difference between the low melting point component and the high melting point component becomes small, and the DSC curve shows the endothermic peaks of the low melting point component and the high melting point component. Appear as one overlapping peak.

The polyethylene-based conjugate fiber of the present invention has an endothermic peak of a low melting point component of 70 ° C. in its DSC curve.
Appearing at ˜125 ° C., and as shown in FIG. 1, the low melting point polyethylene resin component (A) and the high melting point polyethylene resin component (B) show endothermic curves with different endothermic peaks P ₁ and P ₂ , respectively. , L ₁ is the length of a line segment extending vertically from the baseline to P ₁ , and a straight line parallel to the baseline and passing through the midpoint between the baseline and P ₁ is the endothermic curve of the low melting point polyethylene resin component (A). When the length of the line segment that intersects is W, the relationship between L ₁ and W is L ₁ > 3W. The point closest to the baseline formed between the endothermic peaks P ₁ and P ₂ of the two polyethylene resin components is P _3, and the length of a line segment extending vertically from the baseline to P ₃ is L ₂ . Then, the relationship between L ₁ and L ₂ is L ₁ > 3L ₂ . This is a quantitative expression that the melting point of the low melting point polyethylene resin component (A) appears sharply rather than broadly, and has a great meaning to suppress stickiness and deterioration of strength of the fiber surface after processing the nonwoven fabric. It is a thing.

Further, in the composite fiber, the larger the melting point difference between the low melting point polyethylene resin component (A) and the high melting point polyethylene resin component (B), the wider the processing temperature range for forming the nonwoven fabric. Therefore, the processing by the through air processing method, the thermocompression bonding method, or the like becomes easy.
In particular, lowering the melting point of the low melting point polyethylene resin component (A) is economical because the amount of heat of fusion for thermally bonding the composite fibers to each other during processing of the nonwoven fabric is small.

In the polyethylene-based composite fiber of the present invention, it is preferable that the melting point difference between the low-melting point polyethylene resin component (A) and the high-melting point polyethylene resin component (B) is 5 ° C. or more. Is the D shown when the conjugate fiber is measured by using a differential scanning calorimeter (DSC).
In the SC curve, the endothermic peak P ₁ on the low melting point side is subtracted from the endothermic peak P ₂ on the high melting point side. ).

Generally, the melting point of the resin is related to the density of the resin, and the lower the density, the lower the melting point of the resin. However, a resin having a low density generally has a wide Q value and an increased amount of low molecular weight components, so that the melting start temperature is lowered, but the tackiness of the fiber surface and the reduction of the strength of the nonwoven fabric become a problem.

From this point of view also, the low melting point polyethylene resin component (A) of the polyethylene-based composite fiber of the present invention is mainly composed of polyethylene polymerized using a metallocene catalyst suitable for reducing the Q value. Is effective.

When polyethylene polymerized with a generally used Ziegler-Natta catalyst is used as the main component of the low melting point polyethylene resin component (A), the DSC curve of the obtained conjugate fiber is shown in FIG. Thus, the endothermic peak P ₁ of the low melting point polyethylene resin component (A) becomes extremely broad. When the density of the low melting point polyethylene resin component (A) is increased and the endothermic peak P ₁ is sharpened, the melting point is also increased accordingly, and the low melting point polyethylene resin component (A) and the high melting point polyethylene resin component (B) And the DSC curve shows that the endothermic peak P ₁ indicating the melting point of the low melting point polyethylene resin component (A) is absorbed by the endothermic peak P ₂ indicating the melting point of the high melting point polyethylene resin component (B). It becomes one peak.

On the other hand, the polyethylene composite fiber of the present invention has a Q value of 3. when polymerized using a metallocene catalyst.
A low melting point polyethylene resin component (A) containing 0 or less polyethylene as a main component is used, and the density and the density are 0.940.
By combining with a high melting point polyethylene resin component (B) containing polyethylene of g / cm ³ or more as a main component, the DSC curve of the composite fiber shows that the endothermic endotherm of the low melting point polyethylene resin component (A) as shown in FIG. The peak P ₁ appears sharply, and the endothermic peak P ₁ and the endothermic peak P ₂ clearly appear at appropriate intervals. This means that the polyethylene constituting the low-melting point polyethylene resin component (A), which serves as an adhesive component between the fibers during the processing of the nonwoven fabric, has a large molecular weight in the high molecular weight region and has a narrow molecular weight distribution. It shows that the melting point polyethylene resin component (B) and the low melting point polyethylene resin component (A) have distinctly different melting characteristics. As a result, it is understood that the composite fiber having less stickiness and high adhesive strength can be obtained.

FIG. 2 is an example of an actual DSC curve of the polyethylene-based composite fiber of the present invention. As can be seen from FIG. 2, in the DSC curve of the present invention, the endothermic peak of the low melting point component appears relatively sharply.

The low melting point polyethylene resin component (A) referred to in the present invention is a polymer which is polymerized using a metallocene catalyst and which does not have substantially long branched chains, and usually has a proportion of C _{3 to} C _{12 of} not more than 15% by weight. Refers to an ethylene copolymer containing the alkene as a comonomer, generally 0.850 to 0.930 g
/ Cm ³ and a melting point of less than 125 ° C., a Q value of 3.0 or less, 5 to 45 g / 10 min, preferably 25 to
Melt flow rate of 40g / 10min (MFR: J
It is a component containing a linear low-density polyethylene resin having IS K7210 (190 ° C., 2160 g, method B)).

The above polyethylene resin can be easily obtained by using a metallocene catalyst. Typical examples of such metallocene catalysts are bis (cyclopentadienyl) zirconium dichloride, bis (cyclopentadienyl) hafnium dichloride, ethylenebis (indenyl) zirconium dichloride, ethylenebis (indenyl) hafnium dichloride, isopropylidene. (Cyclopentadienyl-9-fluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-9-fluorenyl) hafnium dichloride, isopropylidene (cyclopentadienyl-2,
7-dimethyl-9-fluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-
2,7-Dimethyl-9-fluorenyl) hafnium dichloride, dimethylsilanediylbis (2,4,5-trimethylcyclopentadienyl) zirconium dichloride, dimethylsilanediylbis (2,4-dimethylcyclopentadienyl) zirconium dichloride , Dimethylsilanediylbis (2,4,5-trimethylcyclopentadienyl) hafnium dichloride, dimethylsilanediylbis (2,4-dimethylcyclopentadienyl) hafnium dichloride and the like.

Many of the metallocene polyethylene resins produced by using these catalysts are commercially sold, and among them, the density, melting point, Q value and melt flow rate within the ranges specified above can be selected. It is also possible to appropriately select and use the polyethylene resin to be possessed. In the low melting point polyethylene resin component (A), in addition to polyethylene polymerized using the above metallocene catalyst, LDPE, L-LDPE, V may be used as long as the effects of the present invention are not impaired.
LDPE, ULDPE and HDPE may be blended and used.

In the present invention, the high-melting point component means a polymer of ethylene homopolymerized by a low pressure method using a known Ziegler-Natta catalyst or C _{3 in} a proportion of up to 2% by weight.
Is -C _{1 2} alkene and copolymers of ethylene, the density of generally 0.940~0.960g / cm ³ and 125,
It is a high-density polyethylene resin having a melting point of -135 ° C and a melt flow rate of 5-45 g / 10 min, preferably 20-40 g / 10 min.

As the means for producing the polyethylene-based composite fiber constituted by the present invention, the known melt spinning method and spun bond method can be used. In addition, a composite fiber such as a side-by-side type, a sheath-core type, and an eccentric sheath-core type can be used. The composite ratio of the high melting point component (B) and the low melting point component (A) in the case of producing the conjugate fiber is preferably in the range of 80/20 to 20/80 by weight ratio, and more preferably 50/50 to 70 /.
Thirty. When the content of the high-melting point component (B) is less than the above range, the rigidity of the fiber tends to decrease, so that the card passability does not decrease, and the bulk of the nonwoven fabric does not decrease and the texture is not impaired. Caution must be taken. vice versa,
When the amount of the high-melting point component (B) is increased and the amount of the low-melting point component (A) is lower than the above range, the adhesive strength of the resulting nonwoven fabric tends to be lowered, so care must be taken. Therefore, the composite ratio is best within the above range.

The high melting point component and the low melting point component which compose the polyethylene-based composite fiber of the present invention preferably have a melting point difference of 5 ° C. or more. It becomes wider, making it easier to make nonwoven fabrics. The melting point difference in the present invention refers to the temperature difference between the peak on the high melting point side and the peak on the low melting point side observed in the DSC curve shape of the fiber analyzed by a differential scanning calorimeter (DSC).
The raw material resin used for the fiber of the present invention may contain conventionally known antioxidants, light stabilizers, flame retardants, pigments and the like within a range that does not impair the object of the present invention.

As a method for drawing the polyethylene-based composite fiber constituted by the present invention, known hot roll drawing, hot water drawing and the like can be used, and a one-step drawing method, a two-step drawing method and a multi-step drawing method are used. You can In order to obtain a non-woven fabric having good card-passing properties and being bulky, it is effective to promote the crystal orientation of the fibers and increase the rigidity of the fibers. As a method of increasing the crystal orientation of the fiber, a method of drawing and orienting at a high speed during melt spinning of the fiber and a method of stretching at a high draw ratio are considered. In the case of using the latter method, it is preferable to draw at a draw ratio of at least 5 to 8 times or more, more preferably a polyethylene-based composite fiber having rigidity by being drawn at a high draw ratio of 10 times or more. can get. Further, the crimp holding power of the fiber is also important, and when mechanical crimping by a known stuffer box is applied, sufficient heat is applied to the fiber just before entering the stuffer box so that the crimp holding power of the fiber is improved. improves.

The polyethylene-based conjugate fiber of the present invention includes other fibers which are substantially non-heat-adhesive at the temperature at which the fibers are heat-bonded, such as polypropylene fiber, polyester fiber, polyamide fiber, polyacrylic vinylon and the like. Synthetic fibers, regenerated fibers such as rayon, cupra, acetate, cotton, wool, silk, hemp, pulp fibers, and animal fibers can be mixed and mixed as long as the effects of the present invention are not impaired.

The polyethylene-based conjugate fiber of the present invention can be preferably used as a raw material for a nonwoven fabric. For example, a known embossing method, a through air method, a needle punching method, a hydroentangling method or the like can be used to form a nonwoven fabric, and in particular, the polyethylene-based composite fiber obtained in the present invention has a sheath core having a melting point difference, and thus a heat treatment. With this, a wide processing temperature range can be obtained when forming a nonwoven fabric, and the nonwoven fabric can be suitably used for a heat fusion bonding method using an embossing method or a through air method. When a nonwoven fabric is obtained by the through air method, the web shrinkage rate of the fibers needs to be suppressed to 10% or less (120 ° C. oven heating). If the heat shrinkage rate of the fiber is large, the fiber shrinks due to heat during processing, and problems such as poor dimensional stability, poor formation, and tight pull of the resulting nonwoven fabric occur. To reduce web shrinkage,
It is necessary to improve the fluidity of the resin melted from the nozzle. As a method therefor, it is conceivable to raise the melting temperature during spinning, or to use a resin having a relatively high melt index. When the polyethylene resin is melted at a high temperature, a gel (degradation product due to thermal crosslinking) is generated, which causes yarn breakage during spinning. Therefore, the latter is a more effective means for suppressing web shrinkage. Since the polyethylene-based conjugate fiber of the present invention is less likely to be deteriorated by irradiation with radiation, the resulting nonwoven fabric is used for medical applications such as radiation irradiation clothing, surgical caps, sheets, surgical clothing, surgical gowns, medical examination clothing, etc. Can be widely used as

[0027]

EXAMPLES The present invention will be described in more detail below by showing Examples and Comparative Examples, but the present invention is not limited to these Examples. The raw cotton production conditions, the evaluation methods of the physical properties of Examples and Comparative Examples, and the measured values in the present invention are as shown below.

The raw cotton production conditions used in the present invention are as follows:
With the combination of the high melting point component and the low melting point component polyethylene resin shown in Table 1, the high melting point component was extruded from the spinneret having a pore diameter of 0.8 mm at 240 ° C. and the low melting point component was 200 ° C. at a spinning speed of 376 m / min. Pick up 18.7 dt
A polyethylene composite fiber of ex was obtained. This undrawn yarn is
Using a warm water stretching device filled with warm water of 0 ° C., after stretching 10 times, a zigzag crimp was applied by a push-in type crimper, dried with a hot air suction dryer at 80 ° C., and cut into 51 mm length. . The fineness of the obtained fiber was 2.2 dtex.

The DSC measurement was performed according to JIS7122 using a thermal analyzer DSC10 manufactured by DuPont. D
SC measurement result is the vertical axis of the chart (heat flow rate) 2 W / g
Minutes and 50 ° C. on the abscissa were output so as to be 42 mm, and the lengths (unit: mm) of L ₁ , L ₂ and W were measured.

The non-woven fabric was produced by using a high speed type sample roller card manufactured by Daiwa Kiko Co., Ltd. to fabricate a web having a basis weight of 20 g / m ² and through-air processing and embossing to obtain a non-woven fabric. The non-woven fabric processing conditions are shown below. Through air processing: Using a hot air circulation type suction band dryer, heat fusion was performed at a wind speed of 1.0 m / s and a processing speed of 8.5 m / min. Processing temperature is 110, 11
The temperature was 5, 120, and 125 ° C. Embossing: An embossing machine consisting of an upper and lower pair of an embossing roll having an embossing area ratio of 25% and a flat roll was used to perform thermocompression bonding at a linear pressure of 1.96 MPa and a processing speed of 6.0 m / min. Processing temperature is 105, 110,
It was 115, 120 and 125 ° C.

The strength of the non-woven fabric is measured by measuring the obtained through-air non-woven fabric and the embossed non-woven fabric by 15 cm × 5 cm (MD × C).
D: MD strength measurement sample), 5 cm × 15 cm (MD
X CD: CD strength measurement sample) and cut using a Shimadzu autograph AG-500D with a pulling speed of 20
The breaking strength of the sample was determined at 0 m / min.

The texture of the non-woven fabric was evaluated by 10 panelists, and when 9 or more felt soft, ◎ when 5 or more felt soft, felt soft. The case where there were 4 or less people was Δ, the case where there were 2 people or less who felt to be flexible was marked with X, ◎ and ◯ were in the practical range, and Δ and × were outside the practical range.

Examples 1, 3 and 4 shown in Table 1 are fibers of the present invention having a sheath / core ratio of 30/70 and different sheath densities.
Fibers other than the present invention having a sheath density almost the same as that of the above-mentioned Examples were used as Comparative Examples 1, 2, and 3, and the fibers were subjected to nonwoven fabric processing, and the results of comparing the nonwoven fabric strength and texture are shown in Table 2 ( Examples 6, 8 and 9 of (through air nonwoven fabric), Comparative Examples 6 and 7 and Examples 11 and 1 of Table 3 (embossed nonwoven fabric)
3, 14 and Comparative Examples 8, 9, and 10. The non-woven fabric using the fiber of the present invention has a good texture and high strength, but the non-woven fabric using the fiber other than the present invention impairs the texture and has low tenacity.
In particular, with the fibers formed in Comparative Example 1, a large amount of nep was generated in the card process due to the stickiness of the fibers, the web could not be collected, and the nonwoven fabric could not be processed.

Example 2 in Table 1 is the fiber of the present invention in which the sheath / core ratio of the resin constructed in Example 1 is changed from 30/70 to 50/50, and Example 5 is a sheath resin, L-obtained from Ziegler-Natta catalyst to the extent that it does not hinder the present invention
It is a fiber blended with LDPE. With this fiber,
Table 2 shows the results obtained by processing the nonwoven fabric and measuring the texture strength.
(Through Air Nonwoven Fabric) Examples 7 and 10, Table 3
(Embossed non-woven fabric) Examples 12 and 15 are shown. Both have good texture and high strength.

Comparative Example 4 shown in Table 1 is a non-invention fiber having a sheath / core ratio of 50/50 in which L-LDPE obtained from a Ziegler-Natta catalyst is used on the sheath side. The non-woven fabric could not be made into a non-woven fabric because the difference in melting point of the sheath core was small, and the embossed non-woven fabric could be made into a non-woven fabric only at 120 ° C. as shown in Table 3 and Comparative Example 10. It was extremely hard and had a very bad texture. In Comparative Example 5, L / LDPE obtained from a metallocene catalyst was used on the sheath side, and the sheath / core ratio was 50/5.
When L is 0, L ₁ <3L ₂ and L ₁ <3W, and the fibers are outside the scope of the present invention, but the fibers are highly sticky and nep occurs in the carding process, resulting in a markedly poor texture and non-woven fabric processing. It was

A through-air nonwoven fabric using the fiber obtained in the present invention was cut off from the surface material of a commercially available disposable disposable diaper for adults and compared with Example 16 in which the nonwoven fabrics of Example 6 and Comparative Example 5 were fixed. When the wearing test of Example 11 was conducted, it was confirmed that Example 16 had very good touch and had a strength enough to withstand use, and Comparative Example 11 had poor touch and impaired wearing comfort.

[0037]

[Table 1]

[0038]

[Table 2] Through-air non-woven fabric

[0039]

[Table 3] Embossed non-woven fabric

[0040]

INDUSTRIAL APPLICABILITY The polyethylene-based conjugate fiber of the present invention is easy to process into a non-woven fabric because the fiber has a wide processing temperature range, and the obtained non-woven fabric is flexible and exhibits high non-woven fabric strength. In particular, it can be suitably used as through-air raw cotton that has been difficult to use, and has performance suitable not only for medical applications but also for sanitary materials.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a thermal behavior of a DSC curve of a polyethylene-based composite fiber of the present invention.

FIG. 2 is an example of a DSC curve of the polyethylene-based conjugate fiber of the present invention.

FIG. 3 is an example of a DSC curve diagram of a conventional polyethylene-based composite fiber using polyethylene obtained by using a Ziegler-Natta catalyst for the low melting point component.

[Explanation of symbols]

P _1: endothermic peak P ₂ of a polyethylene resin (A): endothermic peak P ₃ of the polyethylene resin (B): the closest point to the base line formed between the endothermic peak P ₁ and P ₂ L _1: from baseline Length of line segment extending vertically to P ₁ L ₂ : Length of line segment extending vertically from the baseline to P ₃ W: Straight line parallel to the baseline and passing through the midpoint between the baseline and P ₁ Length of line segment that intersects with endothermic curve of component (A)

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) D01F 8/06

Claims (8)

(57) [Claims] 1. A composite fiber comprising two kinds of polyethylene resin components having different melting points, wherein a low melting point polyethylene resin component (A) is polymerized by using a metallocene catalyst and has a density of 0.850 to 0.930 g / cm ^3. , Q value (weight average molecular weight M
w / number average molecular weight Mn) A component containing a polyethylene resin having a molecular weight of 3.0 or less, and a high melting point polyethylene resin component (B)
Is a polyethylene resin having a density of 0.940 g / cm ³ or more,
The fiber is a DSC curve obtained by measurement using a differential scanning calorimeter (DSC) (however, the temperature rising rate is 10 ° C./min, the vertical axis of the DSC chart (heat flow rate, unit: W / g)).
2W / g length is 50 ° C on the horizontal axis (temperature, unit: ° C)
(When the scale is made equal to the length of the minute), the two polyethylene resin components (A) and (B) show endothermic curves having different endothermic peaks P ₁ and P ₂ , respectively, and the DSC curve Let L _{1 be} the length of a line segment that extends perpendicularly from the baseline to the endothermic peak P _{1 of the} low melting point polyethylene resin component (A), and a straight line parallel to the baseline and passing through the midpoint between the baseline and P ₁ is low. Melting point Polyethylene resin component (A)
And the relationship between L ₁ and W is L ₁ > 3W. 2. In the DSC curve of the polyethylene-based composite fiber according to claim 1, the point closest to the baseline formed between the endothermic peaks P ₁ and P ₂ of the two polyethylene resin components is P ₃ . when the length of a line extending perpendicularly from baseline to P ₃ was set to L _2, polyethylene composite fiber relation of L ₁ and L ₂ is characterized in that the L _1> 3L _2. 3. A non-woven fabric using the polyethylene-based composite fiber according to claim 1. 4. A nonwoven fabric using the polyethylene-based composite fiber according to claim 1 or 2, which is obtained by a spunbond method. 5. The non-woven fabric according to claim 3, wherein the fibers are heat-sealed by a through air processing method. 6. The non-woven fabric according to claim 3, wherein the fibers are heat-sealed together by a poin bond processing method. 7. A medical article in which the nonwoven fabric according to any one of claims 3 to 6 is partially used. 8. A sanitary article using a part of the nonwoven fabric according to any one of claims 3 to 6.