KR100451681B1 - Split Polyolefin Composite Fiber and Nonwovens Comprising the Same - Google Patents

Abstract

Split type polyolefin composite fibers and nonwovens are described; The composite fiber is mainly composed of polyolefin resin, at least one resin contains 1.0 to 7.0% by weight of the hydrophilic component blended thereto, and the nonwoven fabric includes microfibers of 0.5 denier or less in size and non-circular in cross section, and divided polyolefin. Obtained by splitting the composite fibers. In the carding step, the generation of static electricity is suppressed by the composite fiber. Nonwovens have excellent wiping properties, flexibility and hydrophilic properties.

Description

Split Polyolefin Composite Fiber and Nonwoven Fabrics Comprising the Same

The present invention relates to split type polyolefin composite fibers and nonwoven fabrics. More specifically, the present invention relates to a split polyolefin composite fiber having excellent splitability and suppressing the generation of static electricity in the carding step. Moreover, the present invention relates to a nonwoven fabric having excellent hydrophilicity, flexibility and wiping properties and obtained from split composite fibers.

Recently, woven or nonwoven fabrics comprising microfine fibers are widely used in terms of their excellent flexibility, feel, wiping properties and high strength. As a method of manufacturing a woven or nonwoven fabric, weaving a so-called "sea-island type composite fiber", a multi-core type composite fiber, generally made from two or more resins having different solubility. A method of producing an ultrafine fiber fabric by converting it into a fabric through a process and then removing the seed component is preferred (Japanese Patent Publication No. 43-7411). In addition, the so-called "split type composite fibers", in which two or more components of low solubility are adhered to each other, are converted into a web using a dry or wet method, and then a high pressure water stream. A method of obtaining a microfiber nonwoven fabric is also carried out by performing a dividing and entanglement process by a mechanical impact such as an impact using a jet of jets (Japanese Patent Publication No. 48-28005, Japanese Unexamined Publication). Japanese Patent Laid-Open No. 5-321018 and Japanese Patent Laid-Open No. 6-63129].

However, the method of using the C-Irish composite fiber requires a weaving step and a step for dissolving the components of the composite fiber, and thus, there is a problem in that the fabrication step of the fabric is complicated.

On the other hand, according to the method using the split composite fiber, the ultrafine fiber nonwoven is easily obtained by simultaneously dividing and entangled the web obtained by the carding process into a high pressure water stream, for example, compared to the above-mentioned method. However, the resins forming the divided composite fibers should be easily divided by mechanical impact (or shock) and are thus selected from the group of polyamides, polyesters, polypropylenes and polyethylenes having low solubility with respect to each other as the resin to be used in the compounding. . Thus, splitting occurs during these steps when the web is formed through a step including a dry carding step. Also, the division is not enough.

Typical synthetic fibers typically apply their surface with a surfactant for the purpose of suppressing the generation of static electricity during the process step. However, due to the above-mentioned splitting process, the surface area of the fiber is increased and static electricity is generated, so that the card passability of the fiber is considerably poor. When further fibrous processing agents are applied in the carding step to suppress the generation of static electricity, problems such as contamination of the carding machine and lowering of the web strength arise.

In the case of conventional split polyolefin composite fibers, hydrophilic surfactants applied to the fiber surface as fiber processing agents are quickly washed off by the high pressure water stream in the nonwoven forming step. On the other hand, polyolefin resins, which are roughly classified as polyethylene, are extremely hydrophobic so that their formula moisture content is 0%. Thus, fibers made of polyolefin avoid the water stream in the initial stages of using a high pressure water stream for nonwoven formation, so that the fibers cannot receive the impact energy of water uniformly. Thus, a nonwoven fabric of microfibers that is sufficiently uniformly divided can be obtained only by increasing the number of steps using a high pressure water stream.

1 to 5 show cross-sectional views of the divided composite fiber of the present invention in which the portions shown by the diagonal lines represent the first component and the blank portions represent the second component. 4, the center part shows the hollow part of a composite fiber.

An object of the present invention is to suppress the generation of static electricity in the carding step using the split composite fiber which is a problem to be solved in the art. It is a further object of the present invention to provide a nonwoven fabric comprising microfine fibers and having excellent wiping properties, flexibility and hydrophilicity.

As a result of the continuous research and development by the inventors of the present invention, it has been found that the above-mentioned problems can be solved by blending a hydrophilic component in one or more polyolefin resins to produce split composite fibers. That is, it has been found that the present invention can be attained by completing the present invention by allowing a hydrophilic component to exist at the interface portion of two components to be split in split polyolefin composite fibers.

The present invention relates to a split polyolefin composite fiber composed mostly of a polyolefin resin wherein at least one resin contains 1.0 to 7.0 wt% of a hydrophilic component blended thereto.

The present invention also relates to a nonwoven fabric comprising microfine fibers obtained by dividing the above-mentioned split polyolefin composite fibers with a thickness of 0.5 denier or less and not circular in cross section.

In the split polyolefin composite fiber of the present invention, the hydrophilic component used is selected from the group consisting of fatty acid glycerides, alkoxylated alkylphenols and polyoxyalkylene fatty acid esters.

Polyolefin resins used in the present invention include homopolymers of ethylene or propylene, copolymers of ethylene or propylene with other α-olefins, and mixtures thereof. As the α-olefin copolymer, a binary or ternary copolymer containing propylene units can be used as the main component. As specific examples of such a copolymer, mention may be made of copolymers of propylene and ethylene, each containing a propylene unit as a main component, a copolymer of propylene and butene-1, or a copolymer of propylene and 4-methyl pentene.

In the present invention, a mixture of polyolefin resin and polyester resin or polyamide resin can be suitably selected for use as the fiber forming resin according to the end use of the fiber.

Split composite fibers of the present invention are characterized in that a radial relationship, a parallel relationship, or two or more polyolefin resins, wherein at least one of the resins contains a hydrophilic component blended therein, as shown in FIGS. It can be obtained by complex spinning in an alternating arrangement.

In the composite fiber of the present invention, additives for imparting other functional properties to the composite fiber can be blended within a range capable of achieving the object of the present invention. Particular additives may be selected and blended in suitable amounts to suit the end use.

The filament denier of the split composite fiber of the present invention is preferably 0.5 to 6.0 denier, more preferably 1.0 to 4.0 denier. If the filament denier of the split composite fiber before dividing is less than 0.5 denier, if a web is formed in the carding step, there is a tendency for nep to occur and non-woven fabric to settle in the cylinder.

Further, when the web is formed by the wet method in which the fibers are dispersed in water, when the filament denier is less than 0.5 denier, the dispersion of the fibers becomes poor in many cases.

On the other hand, when the filament denier exceeds 6.0, the thickness of the composite fiber after dividing is so thick that the wiping characteristics of the nonwoven fabric are undesirably poor.

The thickness of the divided microfine fibers is preferably 0.02 to 0.50 denier. In order to obtain a nonwoven fabric having excellent wiping properties and flexibility, the thickness is more preferably 0.02 to 0.30 denier.

As briefly described above, the hydrophilic component used in the present invention may be suitably selected from nonionic surfactants such as fatty acid glycerides, alkoxylated alkylphenols, polyoxyalkylene fatty acid esters and fatty acid amides, It may be used alone or in a mixture. Among these compounds, the compounds of the following formulas (1), (2) and (3) may be mentioned as examples of preferred hydrophilic components based on the thermal stability during spinning and the ability to impart hydrophilicity to the polyolefin resin.

[Formula 1]

CH ₂ (OR ₁ ) CH (OR ₂ ) CH ₂ (OR ₃ )

[Formula 2]

R-Ph-O- (CH ₂ CH ₂ O) _n -CH ₂ CH ₂ OH

[Formula 3]

R- (CH ₂ CH ₂ O) _n -CH ₂ CH ₂ OH

In Formula 1, Formula 2 and Formula 3 above,

OR ₁ , OR ₂ and OR ₃ are independently hydroxy groups or fatty acid ester groups, provided that at least one of these is a fatty acid ester group,

R is an alkyl group having 1 to 20 carbon atoms in formula (2), a saturated or unsaturated fatty acid ester group in formula (3),

Ph is a phenyl group,

n is an integer from 10 to 55.

The split polyolefin composite fibers of the present invention have a hydrophilic component blended into one or more polyolefin resins, but the hydrophilic component can be blended into all resins.

The amount of hydrophilic component blended in the resin to achieve the object of the present invention is 1.0 to 7.0% by weight, preferably 2.0 to 6.0% by weight. If the amount of hydrophilic component is less than 1.0% by weight, a sufficiently advantageous effect cannot be obtained because undesirably static electricity occurs when the fiber surface area is increased by peeling off or splitting during the carding step. If the amount of hydrophilic component exceeds 7.0% by weight, spinnability becomes undesirably poor in the melt spinning step.

The ratio of the first component to which the hydrophilic component is blended to the second component containing no hydrophilic resin is preferably 5: 5. However, this is not particularly limited to this ratio, and the ratio of the first component is preferably 10 to 90% by weight, more preferably 30 to 70% by weight in the split composite fiber.

The nonwoven fabric of the present invention is 0.5 denier or less, has a non-circular cross section, and is composed of ultrafine fibers obtained by the division of split composite fibers. The nonwoven fabric is, for example, using an opening machine to convert the split composite fibers into a web and then, for example, using a needle punch or a water needle. It can be obtained by dividing the fiber. The basis weight of the nonwoven fabric of the present invention is preferably 20 to 200 g / m ² , more preferably 40 to 150 g / m ² . If the basis weight is greatly outside the above-mentioned range, undesirably the strength of the nonwoven becomes insufficient and uneven, and the division of the composite fiber is also insufficient. The nonwovens of the present invention may be mixtures of the composite fibers of the present invention with other types of polyolefin fibers as long as the mixed nonwovens can be used satisfactorily for the end use of the nonwovens of the present invention.

The composite fibers of the present invention are split using a high pressure water stream. In the aspect according to the object of the present invention, the split ratio is preferably at least 80%. In particular, the split ratio is preferably 85% or more in view of the flexibility and wiping properties of the nonwoven fabric.

The conditions of the split fiber and split ratio are controlled by the high pressure water stream, the speed of the production line, the number of steps using the water stream and the distance between the jet nozzle and the web. Therefore, in order to obtain a split ratio of 80% or more, the water pressure is preferably 60 kg / cm ² or more, more preferably 80 kg / cm ² or more.

In the nonwoven fabric of the present invention, which is less than 0.5 denier and comprises microfibers of non-circular cross-section, the hydrophilic component is blended into the fiber itself, so that even in the case of the end use, which must finally be hydrophilic, There is no need for a post treatment to make the fabric hydrophilic, such as bonding. In addition, when the fiber-forming resin is entirely composed of polyolefin resins, nonwoven fabrics are generally used more broadly because polyolefin resins are excellent in acid resistance and alkali resistance.

Based on the specific structures mentioned above, the nonwoven fabrics of the ultrafine fibers of the present invention are, for example, medical or industrial wiping fabrics, masks, surgical gowns, packaging fabrics, surface materials for hygiene products, reinforcing fibers for building structures and It can be used for a film or film for liquid transport.

Example

The invention will be described in more detail with reference to Examples and Comparative Examples. However, it is to be understood that the present invention is not limited to these specific embodiments unless departing from the gist of the present invention.

In each and the comparative examples, the evaluation of the physical properties of the fibers and the performance of the nonwovens is carried out in the manner mentioned below:

(1) Strength and elongation of a fiber: It measures in accordance with the method of JISL1069. Specifically, the strength (g / d) and elongation (%) are obtained by measuring under conditions of 20 mm length and 20 mm / min elongation ratio of the sample fiber.

(2) Carding process performance: The carding process performance of the fiber is visually evaluated and the results are shown in the following grades.

○: Good (no static electricity and no negative

×: defective (electrostatic generated and the passage state is poor)

(3) Split ratio: Sample fibers are embedded in wax and cut using a microtome almost perpendicular to the fiber axis to obtain a sample piece. The sample pieces were observed under a microscope, imaged on the cross section of the fiber, and measured the total area (A) of the cross section of the split microfiber and the total area (B) of the cross section of the undivided split composite fiber. Calculate the split ratio by the following equation:

[Equation 1]

Split Ratio (%) = A / (A + B) x 100

(4) Texture: The texture of non-woven fabrics is evaluated by hand and is expressed in the following grades.

○: very good

×: slightly bad

(5) Hydrophilicity: A non-woven fabric sample of ultrafine fibers is allowed to stand for 5 hours at a constant temperature of 80 ± 5 ° C. and cooled to room temperature in a desiccator. Subsequently, distilled water adjusted to 23 ± 2 ° C. in a constant temperature water tank is pipetted over a 1 cm height of the nonwoven fabric, so that the location where the water is deposited moves every drop to a total of 20 drops. Hydrophilicity is calculated by the following equation.

[Equation 2]

Hydrophilicity (%) = [number of droplets absorbed within 30 seconds after dripping / total number of droplets (20)] x 100

(6) Wiping characteristics: A specific amount of fat, oil and distilled water are applied to the plane of the glass plate, respectively, and a wiping test is performed using a sample nonwoven fabric. After wiping, the surface of the glass plate was visually observed to evaluate the wiping properties of the nonwoven fabric and the results are shown in the following grades:

○: Good (wiping off fat, oil and water)

X: defective (no fat, oil or water remains on the surface of the glass plate without being wiped and stains on the surface of the glass plate are not removed)

(7) Denier: The denier of the fiber before dividing is cut into 6cm of the fiber bundle before dividing, weighing 150 pieces of cut fibers, calculating the denier and repeating the test five times as denier before dividing. It is determined by taking the average value.

The denier after the split is theoretically obtained from the orifice divided in the spinneret and the filament denier of the fiber before the split.

Table 1 shows the measurement results of the physical properties of the fibers and the performance of the nonwoven fabric.

Example 1

Polypropylene having an MFR (melt flow rate) of 30 g / 10 min at 230 ° C. as a first component, and high density polyethylene having an MFR of 25 g / 10 min at 190 ° C. as a second component of 1% by weight of "ATMER-685". The mixed resin produced by mixing with a mixture of ethoxylated alkylphenols and mixed glycerides (trade name, manufactured by ICI) is extruded through spinnerets for split composite fibers to obtain a volume ratio of the first component to the second component. A split composite fiber having a cross section of 5: 5 as shown in FIG. 1 is formed.

The split composite fiber thus formed was stretched at a draw ratio of 6.0 times, crimped using a crimper to give about 17 crimps / in, and 0.3 wt% of potassium salt of alkyl phosphate as a fiber processing agent. Apply in amounts, then cut. This yields staple fibers having a filament denier of 2.0, a fiber length of 45 mm, a strength of 4.2 g / d and an elongation of 38%.

The staple fibers thus obtained are formed into a web in the carding step and subjected to a process of producing a nonwoven fabric using a high pressure water stream of 80 kg / cm ² .

Table 1 shows the results of the evaluation of the process conditions and the performance of the thus obtained nonwoven fabric.

Example 2

Polypropylene having an MFR of 30 g / 10 min at 230 ° C. as a first component and a low density linear polyethylene having an MFR of 20 g / 10 min at 190 ° C. as a second component are mixed with 2% by weight of the same hydrophilic component as the component added in Example 1 The mixed resin produced thereby is extruded through spinnerets for split composite fibers to form split composite fibers as shown in FIG. 1 having a volume ratio of 5: 5 of the first component to the second component.

The split composite fiber thus formed was stretched at a draw ratio of 4.0 times, crimped using a crimping machine to give about 17 crimps / in, and coated with potassium salt of alkyl phosphate in an amount of 0.3% by weight as a fiber processing agent. Next, cut. This yields staple fibers having a filament denier of 1.3, a fiber length of 45 mm, a strength of 3.5 g / d and an elongation of 38%.

The staple fibers thus obtained are formed into a web in the carding step and subjected to a process of producing a nonwoven fabric using a high pressure water stream of 80 kg / cm ² .

Table 1 shows the results of the evaluation of the process conditions and the performance of the thus obtained nonwoven fabric.

Example 3

Polypropylene having an MFR of 30 g / 10 min at 230 ° C. as a first component and a high density polyethylene having an MFR of 25 g / 10 min at 190 ° C. as a second component were mixed with 6% by weight of the same hydrophilic component as the component added in Example 1 The resulting mixed resin is extruded through spinnerets for split composite fibers to form split composite fibers as shown in FIG. 1 having a volume ratio of 5: 5 of the first component to the second component.

The split composite fiber thus formed was stretched at a draw ratio of 6.0 times, crimped using a crimping machine to give about 17 crimps / in, and coated with potassium salt of alkyl phosphate in an amount of 0.3% by weight as a fiber processing agent. Next, cut. This yields staple fibers having a filament denier of 2.0, a fiber length of 45 mm, a strength of 3.8 g / d and an elongation of 45%.

The staple fibers thus obtained are formed into a web in the carding step and subjected to a process of producing a nonwoven fabric using a high pressure water stream of 80 kg / cm ² .

Table 1 shows the results of the evaluation of the process conditions and the performance of the thus obtained nonwoven fabric.

Example 4

Polypropylene having an MFR of 30 g / 10 min at 230 ° C. as a first component and a high density polyethylene having an MFR of 25 g / 10 min at 190 ° C. as a second component were mixed with 6% by weight of the same hydrophilic component as the component added in Example 1 The resulting mixed resin is extruded through spinnerets for split composite fibers to form split composite fibers as shown in FIG. 1 having a volume ratio of 5: 5 of the first component to the second component.

The split composite fiber thus formed was stretched at a draw ratio of 6.0 times, crimped using a crimping machine to give about 17 crimps / in, and coated with potassium salt of alkyl phosphate in an amount of 0.3% by weight as a fiber processing agent. Next, cut. This yields staple fibers having a filament denier of 6.0, a fiber length of 51 mm, a strength of 3.5 g / d and an elongation of 55%.

The staple fibers thus obtained are formed into a web in the carding step and subjected to a process of producing a nonwoven fabric using a high pressure water stream of 80 kg / cm ² .

Table 1 shows the results of the evaluation of the process conditions and the performance of the thus obtained nonwoven fabric.

Example 5

Polypropylene having an MFR of 30 g / 10 min at 230 ° C. as a first component and a high density polyethylene having an MFR of 25 g / 10 min at 190 ° C. as a second component are mixed with 7% by weight of the same hydrophilic component as the component added in Example 1 The resulting mixed resin is extruded through spinnerets for split composite fibers to form split composite fibers as shown in FIG. 1 having a volume ratio of 5: 5 of the first component to the second component.

The split composite fiber thus formed was stretched at a draw ratio of 6.0 times, crimped using a crimping machine to give about 17 crimps / in, and coated with potassium salt of alkyl phosphate in an amount of 0.3% by weight as a fiber processing agent. Next, cut. This yields staple fibers having a filament denier of 2.0, a fiber length of 45 mm, a strength of 3.6 g / d and an elongation of 32%.

The staple fibers thus obtained are formed into a web in the carding step and subjected to a process of producing a nonwoven fabric using a high pressure water stream of 80 kg / cm ² .

Table 1 shows the results of the evaluation of the process conditions and the performance of the thus obtained nonwoven fabric.

Example 6

A mixed resin prepared by mixing a polypropylene having a MFR of 30 g / 10 min at 230 ° C. as the first component with 3 wt% of the same hydrophilic component as the component added in Example 1, and 25 g / MFR at 190 ° C. as a second component. The mixed resin prepared by mixing 10 min high-density polyethylene with 3 wt% of the same hydrophilic component as the component added in Example 1 was extruded through spinnerets for split composite fibers to give a volume ratio of the first component to the second component of 5 A split composite fiber as shown in Fig. 1 having a cross section of 5 was formed.

The split composite fiber thus formed was stretched at a draw ratio of 5.0 times, crimped using a crimping machine to give about 17 crimps / in, and coated with potassium salt of alkyl phosphate in an amount of 0.3% by weight as a fiber processing agent. Next, cut. Subsequently, staple fibers having a filament denier of 2.0, a fiber length of 51 mm, a strength of 3.5 g / d and an elongation of 45% are obtained.

The staple fibers thus obtained are formed into a web in the carding step and subjected to a process of producing a nonwoven fabric using a high pressure water stream of 80 kg / cm ² .

Table 1 shows the results of the evaluation of the process conditions and the performance of the thus obtained nonwoven fabric.

Examples 7 and 8

The nonwoven fabric is prepared in the same process as in Example 3 except that the web is processed in two or three steps using a water stream at a pressure of 80 kg / cm ² .

Table 1 shows the results of the evaluation of the process conditions and the performance of the thus obtained nonwoven fabric.

Comparative Example 1

Polypropylene having an MFR of 30 g / 10 min at 230 ° C. as a first component and a high density polyethylene having an MFR of 25 g / 10 min at 190 ° C. as a second component are extruded through spinnerets for split composite fibers to form a first to second component. A cross-sectional cross section having a volume ratio of 5: 5, as shown in Fig. 1, forms a composite fiber.

The split composite fiber thus formed was stretched at a draw ratio of 6.0 times, crimped using a crimping machine to give about 17 crimps / in, and coated with potassium salt of alkyl phosphate in an amount of 0.3% by weight as a fiber processing agent. Next, cut. This yields staple fibers having a filament denier of 2.0, a fiber length of 51 mm, a strength of 4.3 g / d and an elongation of 30%.

The staple fibers thus obtained are formed into a web in the carding step and subjected to a process of producing a nonwoven fabric using a high pressure water stream of 80 kg / cm ² .

Table 1 shows the results of the evaluation of the process conditions and the performance of the thus obtained nonwoven fabric.

Comparative Example 2

Polypropylene having an MFR of 30 g / 10 min at 230 ° C. as a first component and a high density polyethylene having an MFR of 25 g / 10 min at 190 ° C. as a second component are mixed with 0.5% by weight of the same hydrophilic component as the component added in Example 1 The resulting mixed resin is extruded through spinnerets for split composite fibers to form split composite fibers as shown in FIG. 1 having a volume ratio of 5: 5 of the first component to the second component.

The split composite fiber thus formed was stretched at a draw ratio of 6.0 times, crimped using a crimping machine to give about 17 crimps / in, and coated with potassium salt of alkyl phosphate in an amount of 0.3% by weight as a fiber processing agent. Next, cut. This yields staple fibers having a filament denier of 2.0, a fiber length of 45 mm, a strength of 4.0 g / d, and an elongation of 32%.

The staple fibers thus obtained are formed into a web in the carding step and subjected to a process of producing a nonwoven fabric using a high pressure water stream of 80 kg / cm ² .

Table 1 shows the results of the evaluation of the process conditions and the performance of the thus obtained nonwoven fabric.

Comparative Example 3

9 weights of the same hydrophilic components as those added in Example 1, polypropylene having a MFR (melt flow rate) of 30 g / 10 min at 230 ° C. as a first component, and a high density polyethylene having a MFR of 25 g / 10 min at 190 ° C. as a second component. The mixed resin produced by mixing with% is extruded through spinnerets for split composite fibers to form split composite fibers. However, filament drawing is so unstable that sample fibers cannot be obtained.

Comparative Example 4

6 weights of the same hydrophilic component as the component added in Example 1, polypropylene having a MFR (melt flow rate) of 10 g / 10 min at 230 ° C. as a first component, and a high density polyethylene having a MFR of 25 g / 10 min at 190 ° C. as a second component. The mixed resin produced by mixing with% is extruded through spinnerets for sheath-core type composite fibers, so that the volume ratio of the first component to the second component is 5: 5. To form a composite fiber.

The composite fiber thus formed was stretched at a draw ratio of 4.0 times, crimped using a crimping machine to give about 17 crimps / in, and coated with potassium salt of alkyl phosphate in an amount of 0.3% by weight as a fiber processing agent. Cut. Subsequently, staple fibers having a filament denier of 2.0, a fiber length of 45 mm, a strength of 3.2 g / d and an elongation of 77% are obtained.

The staple fibers thus obtained are formed into a web in the carding step and subjected to a process of producing a nonwoven fabric using a high pressure water stream of 80 kg / cm ² .

Table 1 shows the results of the evaluation of the process conditions and the performance of the thus obtained nonwoven fabric.

Comparative Example 5

Comparative Example 1 is repeated except that the process using a water stream with a pressure of 80 kg / cm ² is carried out in two steps.

Table 1 shows the results of the evaluation of the process conditions and the performance of the thus obtained nonwoven fabric.

TABLE 1

Table 1 (continued)

Since the composite fibers of the present invention are polyolefin resins in which the hydrophilic components are blended to maintain the hydrophilic effect, the split composite fibers of the present invention exhibit good carding process performance with little splitting or peeling during the carding process.

Even when the composite fiber of the present invention causes a certain degree of splitting or peeling during the carding process, the hydrophilic component blended into the resin flows out so that static electricity is suppressed, no nep occurs, and improved carding process performance is achieved. Indicates.

The composite fiber of the present invention contains a hydrophilic component blended into the fiber itself, and even when the hydrophilic surfactant, once applied to the surface of the fiber, is washed off as a fiber processing agent, the hydrophilic component appears on the surface of the composite fiber.

The composite fibers of the present invention do not repel water and do not become bulky, but maintain wettable surface conditions even during processes using a high pressure water stream (aka water needle process) because the fibers maintain a hydrophilic effect. Thus, the split ratio is significantly enhanced in processes using high pressure water streams.

In the case of using the composite fiber of the present invention, a hydrophilic component appears on the surface formed by the division. Thus, the wettability of the fibers is increased, and the fibers do not avoid water even when repeating the process of using water to form the nonwoven fabric, and are uniformly subjected to the impact energy by the water. Thus, a small number of process steps yields a nonwoven fabric of microfibers that is evenly divided to a sufficient degree.

Nonwoven fabrics of the present invention comprising ultrafine fibers have a low number of undivided fibers contained in the nonwoven fabric. The microfine fibers are uniformly dispersed and entangled with each other in the nonwoven fabric. Moreover, the nonwoven fabric is flexible and retains hydrophilicity because the hydrophilic component is blended into the fibers.

Since the nonwoven fabric of the present invention contains a hydrophilic component blended into the fiber and includes a polyolefin microfiber having a non-circular cross-section, the nonwoven fabric of the present invention is not only resistant to contamination by fats and oils, but also by impurities in water. Ping characteristics are shown.

Claims (4)

Segmented polyolefin composite fiber, consisting mainly of polyolefin resins, characterized in that at least one of these polyolefin resins contains 1.0 to 7.0% by weight of hydrophilic component blended thereto. The split polyolefin composite fiber according to claim 1, wherein the hydrophilic component is at least one compound selected from the group consisting of fatty acid glycerides, alkoxylated alkylphenols and polyoxyalkylene fatty acid esters. A nonwoven fabric comprising microfine fibers having a thickness of 0.5 denier or less and a cross section not circular, obtained by dividing the divided polyolefin composite fibers as defined in claim 1. A nonwoven fabric comprising microfine fibers having a thickness of 0.5 denier or less and having a cross section that is not circular, obtained by dividing the divided polyolefin composite fibers as defined in claim 2.