JP2001040531A - Latent crimping conjugate fiber and nonwoven fabric using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a latently crimpable conjugate fiber which is suitable for producing a nonwoven fabric which is bulky and has a good texture and which exhibits crimp by heat treatment, and a nonwoven fabric using the same. Make it an issue. The melting point Tm (° C.) is 120 ≦ Tm ≦ 147.
A propylene copolymer comprising 90 to 98% by weight of propylene and 2 to 10% by weight of an α-olefin other than propylene as a first component, and polyethylene as a second component, wherein the first component is The composite form of the second component and the second component is an eccentric sheath-core type in which the second component is arranged on the sheath side, and the area ratio of the first component to the second component in the fiber cross section is 65.
/ 35-35 / 65, latently crimpable conjugate fiber

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin-based composite fiber having latent crimping properties, in which crimps are developed by heat treatment, and a nonwoven fabric using the same.

[0002]

2. Description of the Related Art Conventionally, as a method for obtaining a bulky nonwoven fabric, a fiber provided with a zigzag type mechanical crimp using a crimping means such as a crimper, or a composite form of the fiber is arranged in parallel or eccentric. There has been a method of using a fiber having a sheath-core type and having a helical three-dimensional crimp by generating distortion inside the fiber by means such as stretching.

For example, Japanese Patent Application Laid-Open No. 2191720 proposes a sheath-core composite fiber in which an ethylene-propylene random copolymer is mainly disposed as a sheath component and crystalline polypropylene is disposed as a core component. . This is achieved by applying a heat treatment to the web made of the fiber, utilizing the heat shrinkage characteristics of the ethylene-propylene random copolymer used as the sheath component, developing a latent crimp during nonwoven fabric processing, and forming a bulky nonwoven fabric. It is manufactured. However, the metal friction resistance of the ethylene-propylene random copolymer disposed in the sheath component is generally much larger than other resins used for fibers, for example, high-density polyethylene, so that it is difficult to be discharged from the card machine and uniform. There is a problem that it is difficult to obtain a web, and the obtained nonwoven fabric also has a unique slimy feeling and sticky feeling due to the properties of the resin as the sheath component. In addition, raw cotton is generally spread by a fiber opening machine and transported to a card machine by a blower tube. However, a fiber having a large metallic friction resistance has a problem of poor transportability in which cotton adheres to a wall surface of the blower tube. Furthermore, even when a composite long fiber is spun by combining these resins by a spunbonding method that does not require a carding process, the fiber is opened due to the high fiber-to-fiber friction of the ethylene-propylene random copolymer covering the fiber surface. There was a problem that the fineness was poor and the web accumulated on the conveyor was not sufficiently uniform. As described above, up to now, a bulky and well-formed nonwoven fabric using fibers having latent crimpability has not been obtained, but in recent years, with the intensifying competition in the market for disposable diapers and sanitary products, There has been an increasing demand for bulky nonwoven fabrics having a better texture.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a nonwoven fabric which is bulky and has a good texture and a latent crimpable conjugate fiber which is a raw material thereof.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found the following means, and have completed the present invention. The present invention has the following configurations. (1) When the melting point Tm (° C.) is 120 ≦ Tm ≦ 147 and 90
A conjugated fiber comprising a propylene copolymer consisting of .about.98% by weight of propylene and 2-10% by weight of an .alpha.-olefin other than propylene as a first component, and polyethylene as a second component. Second form of compound
An eccentric sheath-core type in which the components are arranged on the sheath side, and the area ratio of the first component and the second component in the fiber cross section is 65/35 to
A latently crimpable conjugate fiber having a ratio of 35/65. (2) The latent winding according to the above (1), wherein the first component is a propylene copolymer comprising 90 to 96% by weight of propylene and 4 to 10% by weight of an α-olefin other than propylene. Shrinkable conjugate fiber. (3) the first component is 90 to 96% by weight of propylene,
3 to 7% by weight of ethylene and 1 to 5% by weight of butene
The latently crimpable conjugate fiber according to any one of the above (1) to (2), which is an ethylene-propylene-butene-1 terpolymer composed of 1. (4) The above-mentioned (1) to (3), wherein the second component comprises at least one selected from high-density polyethylene, linear low-density polyethylene, and low-density polyethylene.
Item 14. The latently crimpable conjugate fiber according to any of the above items. (5) The latent crimpability according to any one of the above (1) to (4), wherein the second component is a polyethylene having a melting point lower than the melting point Tm (° C.) of the first component. Composite fiber. (6) The latently crimpable conjugate fiber according to any one of the above (1) to (5), wherein the latently crimpable conjugate fiber is a long fiber. (7) A nonwoven fabric comprising the latently crimpable conjugate fiber according to any one of the above (1) to (6).

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described. The first component constituting the latently crimpable conjugate fiber of the present invention
As a component, from the viewpoint of processability, heat shrinkage is caused at a relatively low temperature, and a melting point Tm (° C.) having a fiber forming property.
Is in the range of 120 ≦ Tm ≦ 147. Such a propylene copolymer can be obtained by mainly copolymerizing propylene with another α-olefin. Examples of such α-olefins include ethylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1,
Examples thereof include 4-methyl-pentene-1 and the like, and two or more of these α-olefins can be used in combination. Specific examples of the propylene copolymer include ethylene-propylene binary copolymer, propylene-butene-1 binary copolymer, ethylene-propylene-butene-1 ternary copolymer, and propylene-hexene-1 binary copolymer. Examples thereof include polymers, propylene-octene-1 binary copolymers, and the like, and mixtures thereof. These copolymers are usually
Although it is a random copolymer, it may be a block copolymer.

Among the propylene copolymers which can be used as the first component of the latently crimpable fiber of the present invention and have a melting point Tm (° C.) within the aforementioned range, 90 to 98% by weight of propylene, 1 to 7% by weight. Ethylene-propylene-butene-1 terpolymer composed of 1% to 5% by weight of ethylene and 1 to 5% by weight of butene-1; 90 to 98% by weight of propylene;
Ethylene-propylene binary copolymer composed of 0% by weight of ethylene is preferable from the viewpoint of cost, and from the viewpoint of low-temperature processability and shrinkage force when shrinking by heat, from 90 to 96% by weight as the first component. Propylene, 4 to 10% by weight
Ethylene-propylene binary copolymer comprising ethylene of 90 to 96% by weight, ethylene comprising 3 to 7% by weight of ethylene, and 1 to 5% by weight of butene-1.
It is more preferable to use a propylene-butene-1 terpolymer. In these resins, the melting point Tm (° C.)
Is less than 120 ° C. to show rubber elasticity,
It adversely affects the card processability of the resulting fiber. Also,
When a propylene copolymer having a melting point Tm (° C.) of more than 147 ° C. is used as the first component, the shrinkage of the obtained fiber is reduced to a level of ordinary polypropylene single component fiber or polyethylene / polypropylene composite fiber. I will. Therefore, by using a propylene copolymer having a composition within the above-described range as the first component, card processability,
A latently crimpable fiber having both heat shrinkability can be obtained. In addition, as long as the heat shrinkage of the fiber of the present invention is not extremely reduced or the heat shrinkage is slightly suppressed, the first component may include titanium dioxide, calcium carbonate, magnesium hydroxide and the like as necessary. Minerals, flame retardants,
Pigments and other polymers can be added.

The polyethylene which can be used as the second component of the latently crimpable fiber of the present invention includes high-density polyethylene, linear low-density polyethylene, and low-density polyethylene which are roughly classified into the following melting points and density categories. Polyethylene can be mentioned.

The high-density polyethylene referred to in the present invention is a polymer of ethylene alone or a small amount, usually a proportion of up to 2% by weight of C3 to C12, polymerized by a low-pressure method using a known Ziegler-Natta catalyst. Of an alkene as a comonomer, generally having a density of 0.941 to 0.965 g / cm ³ ,
It is a polyethylene having a melting point of 7 ° C. or more.

[0010] The linear low-density polyethylene referred to in the present invention is a polymer which has been polymerized using a known Ziegler-Natta catalyst.
It refers to an ethylene-based copolymer having substantially no branched chain and containing a C3-C12 alkene in a proportion of usually 15% by weight or less as a comonomer.
Polyethylene having a density of ０．９0.940 g / cm ³ and a melting point of less than 127 ° C.

The low-density polyethylene referred to in the present invention is generally a polymer obtained by a high-pressure method and having a density of 0.910 to 0.940.
It is a polyethylene having a high degree of branching and low crystallinity having a g / cm ³ and a melting point of 120 ° C. or lower.

Further, a polyethylene resin polymerized using a metallocene catalyst has an even lower melting point than the above-mentioned resins, so that it is advantageous from the viewpoint of low-temperature processability when heat bonding fibers to each other. Since it has a narrow molecular weight distribution and greatly contributes to spinning stability, it can be suitably used as the second component of the present invention. When producing the latently crimpable fiber of the present invention, in order to impart low-temperature processability and process stability, several kinds of resins selected from these polyethylenes are mixed, or the object of the present invention is If not hindered, inorganic materials such as titanium dioxide, calcium carbonate and magnesium hydroxide, flame retardants, pigments and other polymers may be added to the second component as needed.

In the latently crimpable fiber of the present invention, the second
By using polyethylene having a melting point lower than the melting point Tm (° C.) of the first component as a component, it is possible to impart thermal adhesiveness to the fiber. That is, if the resin is appropriately selected so that the first component and the second component have a melting point difference as needed, the fibers are entangled with each other by a technique such as embossing or heat pinning on a web in which the fibers are entangled by a high-pressure water flow. The strength of the nonwoven fabric can be improved and the elasticity can be adjusted within a range that does not impair the texture and bulkiness of the nonwoven fabric by heat bonding. In particular, when heat treatment is performed in a temperature range equal to or lower than the melting point of the first component and equal to or higher than the melting point of the second component, nonwoven fabric formation and shrinkage treatment can be performed simultaneously, so that the nonwoven fabric manufacturing process can be simplified. At this time, the melting point of the second component is 5 ° C. or more, more preferably 10 ° C., higher than the melting point Tm (° C.) of the first component.
It is desirable that the temperature is lower by at least C. Further, depending on the use of the nonwoven fabric, a crimp can be developed by a heat treatment at a temperature low enough that the fibers do not thermally bond to each other (less than the melting points of both components), and the nonwoven fabric can be manufactured only by entanglement of the fibers. If a nonwoven fabric that can withstand practical use can be obtained only by developing latent crimp by heat shrinkage at a temperature lower than the melting points of both components, the melting point of the second component is not necessarily the melting point T of the first component.
It does not need to be below m (° C).

A cross-sectional view of the latently crimpable fiber of the present invention is shown in FIGS. The composite form of the first component and the second component in the latently crimpable conjugate fiber of the present invention needs to be an eccentric sheath-core type in which the second component is disposed on the sheath side. This is because, when the conjugate fiber has a concentric structure, even when heat treatment is performed, crimping that can sufficiently express bulkiness does not occur. The eccentric sheath-core type arrangement generally has a cross-sectional shape as shown in FIG. 1, but increases the degree of eccentricity as shown in FIG.
Even if the component is partially exposed on the surface of the fiber, the potential crimpability can be enhanced, so long as the effect of the present invention is not hindered by the friction of the first component partially exposed on the fiber surface. Can be adopted. Furthermore, as shown in FIG. 3, even when the cross-sectional shape of the core component is irregular (non-circular), the potential crimpability due to the difference in heat shrinkage can be increased.

The area ratio between the first component and the second component of the conjugate fiber (that is, the area ratio between the sheath component and the core component in a cross section obtained by cutting the fiber in a direction perpendicular to the fiber axis direction) is 35 /
It is preferably in the range of 65 to 65/35, and more preferably in the range of 45/55 to 55/45. If the area ratio of the first component is much less than 35%, the shrinkage force caused by the latent crimping property during heat treatment (during shrinkage processing) is reduced, and the fiber cannot be sufficiently crimped. For this reason, a bulky nonwoven fabric may not be obtained. Conversely, if it exceeds 65%, the fibers are excessively shrunk, so that it is difficult to uniformly shrink the nonwoven fabric. This is because lumps may be generated and a nonwoven fabric may not be obtained.

The latently crimpable conjugate fiber of the present invention, when processed into a web, has a heat shrinkage of at least 50% in the machine direction of the fiber (hereinafter abbreviated as MD) as measured by a method described later. Considering the case where other fibers are mixed and used, MD60% or more, CD
It is more preferable to exhibit a heat shrinkage of 40% or more (in the direction perpendicular to the MD). If the heat shrinkage in MD is significantly lower than 50%, the bulk of the obtained nonwoven fabric will be low.

Examples of the method for producing the fiber of the present invention include various known spinning methods such as a melt spinning method, a spun bond method and a melt blow method. By appropriately using these processing methods, multifilaments, monofilaments, and the like can be used. Staple fiber, tow, and non-woven fabric can be obtained.

When the latently crimpable fiber of the present invention is used as a staple fiber requiring a carding step, it is necessary to impart an apparent crimp to the fiber. In this case, a mechanical crimping means generally used, In addition to using a so-called stuffer box type crimper, a helical three-dimensional crimp can also be provided without using a stuffer box type crimper by utilizing the difference between the elongation elastic moduli of the first component and the second component. .

For short fiber samples such as staple fibers, an appropriate number of crimps must be applied in order to process the fibers into a web on a carding machine. The number of crimps has an appropriate range depending on the fineness of the fiber.
Preferably, it is 0 to 25 peaks / 2.54 cm (1 inch). If the number of crimps is significantly below this range, problems such as the fibers wrapping around the cylinder or doffer or the web being cut during card processing are likely to occur. Occasionally, a nep tends to occur,
There is a problem that it is difficult to obtain a uniform web. In order to obtain a bulky and well-formed nonwoven fabric, it is necessary to adjust the number of crimps within the above-mentioned range.

The fineness of the fiber is not particularly limited, and is appropriately selected depending on the use of the fiber. For example, when used for sanitary materials represented by absorbent articles such as disposable diapers and surface materials of sanitary napkins, 0.1%
10 to 10 dtex, 8 to 80 when used for needle punch carpets, tufted carpets, etc.
When it is used for civil engineering materials such as a range of dtex and monofilament, a range of 50 to 7000 dtex is preferable.

In the melt spinning method, when the latently crimpable conjugate fiber of the present invention is a short fiber, the cut length of the fiber is not particularly limited, and may be appropriately selected depending on the processing method and application of the fiber to be used. do it. When it is necessary to obtain a fibrous web such as a random web, a parallel web or a cross-wrap web using a roller card machine or a random webber, the cut length is preferably set to 20 to 125 mm. For this purpose, a cut length of 25 to 75 mm is more preferable.
When a fiber web is manufactured by an air laid method or a papermaking method, the cut length is preferably less than 20 mm.

In order to produce a bulky nonwoven fabric using the latently crimpable conjugate fiber of the present invention, a fiber aggregate (web) mainly composed of the latently crimpable conjugate fiber of the present invention is subjected to heat treatment. , At the same time as developing the potential crimp of the fiber,
It is necessary to shrink and integrate the web. For the heat treatment, a general-purpose hot air circulation device or a heat treatment device such as a floating drier can be used, but the use of a floating drier capable of more uniformly shrinking the web is more preferable. The feature of this device is that hot air is blown out from nozzles installed on the upper and lower surfaces of the web transfer space,
This hot air causes the web to float, and causes thermal shrinkage at the same time as air conveyance, whereby a more uniform nonwoven fabric can be obtained. However, in order to prevent the web from being cut or the fibers from being scattered when using any of the devices, a known nonwoven fabric processing such as a needle punching method, an embossing roll method, an ultrasonic fusing method and / or a high-pressure hydroentanglement method is used. It is important to temporarily hold the web by using the method.

The basis weight of the nonwoven fabric comprising the latently crimpable conjugate fiber of the present invention is appropriately selected depending on the purpose of use. For example,
When used as a surface material for absorbent articles, 5 to 10
The range of 0 g / m ² is preferable, and the range of 50 to 2000 g / m ² is preferable when used for civil engineering materials such as drain materials. Further, the nonwoven fabric can be laminated according to the purpose, and a combination of spunbonded nonwoven fabric / nonwoven fabric of latently crimped conjugate fiber / spunbonded nonwoven fabric, nonwoven fabric of spunbonded nonwoven fabric / meltblown nonwoven fabric / latently crimped conjugate fiber Can be exemplified.

The latently crimpable conjugate fiber of the present invention is used not only alone but also with other fibers in a range not interfering with the effects of the present invention. By mixing the fibers, a primary fiber product such as a knitted fabric or a fiber molded product can be obtained. In addition, since the fiber of the present invention has a moderate elasticity and a good texture after developing the latent crimping property, it is further subjected to secondary processing, so that clothing such as underwear, shirts, blouses, socks, socks, etc. Fields, bedding such as cotton padding, futon side lining, sheets, bedspreads, pillowcases, cushions, etc., surgical masks, surgical gowns, caps, medical gowns, gauze, bandages, etc. Non-pharmaceutical fields, sanitary products, disposable disposable diapers, hygiene materials such as incontinence pads, bedding interiors such as carpets, curtains, wallpapers, etc., shoe lining materials, insoles, footwear materials, etc., fruit protection materials, and prevention of food damage Agricultural and horticultural materials such as lumber,
Confectionery packaging, food packaging, furoshiki, towels, towels,
It can be used in a wide range of fields such as filter materials such as scourers, tablecloths, aprons, kitchen cloths, cosmetic puffs, tea packs, wiping cloths and the like. Other fibers used for blending, blending, blending, blending, knitting, blending and the like are not particularly limited. For example, polyamide fibers such as nylon 6, nylon 66, polyethylene terephthalate, polyester fibers such as polybutylene terephthalate, polypropylene,
Polyolefin fibers such as polyethylene and polyethylene / polypropylene composite fibers can be used according to the purpose.

[0025]

EXAMPLES Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to the following examples. The definitions of the terms used in the examples and comparative examples and the measurement method are as follows. (1) Melting point: (unit: ° C.) According to a differential scanning calorimeter DSC-10 manufactured by DuPont,
The temperature corresponding to the peak on the melting absorption curve obtained when the temperature of the thermoplastic polymer was raised at 10 ° C./min was defined as the melting point of the thermoplastic polymer. (2) MFR: (unit: g / 10 min) JIS K7210 Condition 14 (230 ° C., 21.1)
8N). MFR (before spinning) is a value measured using a thermoplastic polymer as a sample, and MFR (after spinning).
Is a value measured after melt extruding with a spinning machine and taken as a sample of a cooled thermoplastic polymer. (3) Q value: (weight average molecular weight / number average molecular weight) The Q value is a ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the thermoplastic polymer obtained by gel permeation chromatography. Mw / Mn). Here, the values of the thermoplastic polymer before spinning are shown. (4) Fineness: (unit: dtex) The fibers were observed with a scanning electron microscope, the diameter of 100 fibers was measured from the obtained image, and the fineness was calculated from the average value. (5) Number of crimps: (unit number of peaks / 2.54 cm) For short fiber samples, 2.5 for 10 fibers
The number of crimps per 4 cm was counted, and the average value was used as the number of crimps here. (6) Thermal shrinkage: (unit%) A web having a size of 25 × 25 cm and a basis weight of about 200 g / m ² was placed on a kraft paper, placed in a convection hot air dryer maintained at 145 ° C., and heated for 5 minutes. M of web before and after heat treatment
From the respective lengths of D and CD, the heat shrinkage was calculated by the following equation. Heat shrinkage (%) = (1-a / 25) × 100 where a is the length of the MD or CD of the heat-treated web. (7) Spinnability When spinning was performed by the melt spinning method, the number of occurrences of yarn breakage per 10 hours was measured, and spinnability was evaluated in the following three stages. Good: No yarn breakage, most preferable for production. Good: One or more times less than three times the number of thread breaks. Defective: Thread breakage occurs 4 times or more, and there is a problem in production efficiency. (8) Card Suitability 50 g of raw cotton was put into a miniature card machine, and the web discharged from the miniature card machine and the state of the fibers in the miniature card machine were visually judged according to the following criteria. Suitable: Uniform web with good formation and good dischargeability. Inappropriate: Raw cotton wraps around the cylinder or doffer inside the card machine and has problems in processing. (9) Web with a basis weight of about 20 g / m ² Then, a heat treatment was performed for 1 minute in a hot air circulation device heated to 145 ° C., and the formation of the obtained nonwoven fabric was visually judged according to the following three-step criteria. Good: Non-woven fabric with uniform heat shrinkage and good texture was obtained. Good: Thermal shrinkage occurred almost uniformly, and slight disturbance of the texture was observed, but it was considered that there was no practical problem. Shrinkage does not occur uniformly and the texture is disordered, or the shrinkage is small. (10) Texture A web having a basis weight of about 20 g / m ² was subjected to a heat treatment for 1 minute in a hot air circulation device maintained at 145 ° C. . By the sensory test by 10 panelists,
The texture was rated on a four-point scale based on the following criteria, and the average value was rounded off for evaluation. 4: Non-woven fabric is bulky and stretchable and has a smooth and soft surface. 3: Non-woven fabric is bulky and soft but slightly lacks or lacks smoothness. 2: Non-woven fabric has no bulk and feels hard. In addition, those lacking elasticity 1: hardly shrink, and are broken by pulling lightly, which poses a practical problem. (11) Spreadability Fiber spun by a spunbond spinning device is captured on an endless net conveyor. The opened state of the collected and collected long fiber web was visually evaluated in the following three stages. Good: Opened evenly Good: Opened almost uniformly, with a small degree of density Bad: Disturbed opening, and considered to be unusable as a product

Examples 1 to 8 and Comparative Examples 1 to 3 Either ethylene-propylene-butene-1 terpolymer, ethylene-propylene binary copolymer or crystalline polypropylene was used as the first component. Density polyethylene, linear low density polyethylene, low density polyethylene,
Either polyester (intrinsic viscosity (IV value) 0.67) or crystalline polypropylene as the second component, an extruder, an eccentric sheath core spinneret with a hole diameter of 0.8 mm, a parallel spinneret or a concentric sheath Using a spinning device equipped with a core-type spinneret, a spinning device equipped with a winding device, and a drawing device equipped with a multi-stage heating roll and a stuffer box type crimper, a conjugate fiber is manufactured, and the resulting fiber is subjected to heat shrinkage. The rate was measured.

With respect to the data of each conjugate fiber and nonwoven fabric, Examples 1 to 8 are shown in Tables 1 and 2, and Comparative Examples 1 to 3 are shown in Table 3.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

In Comparative Example 1, the crystalline polypropylene used as the first component (containing 0.24% by weight of ethylene component)
However, due to poor heat shrinkability, even if heat treatment was applied to the produced conjugate fiber, sufficient crimp did not appear and the heat shrinkage was extremely low. In Comparative Example 2, the first component used was the same as that in Example 2. However, since the rigidity of the polyester used as the second component was high, heat shrinkage did not occur, and a bulky nonwoven fabric was not obtained. Was. In Comparative Example 3, since the composite form was concentric, a sufficient crimp was not obtained. Furthermore, in Comparative Examples 1 to 3, the fibers did not shrink with hot air at 145 ° C, and a nonwoven fabric could not be obtained.

Examples 9 to 12 and Comparative Examples 4 to 5 Either ethylene-propylene-butene-1 terpolymer, ethylene-propylene binary copolymer or crystalline polypropylene was used as the first component. Composite length using any one of high density polyethylene, linear low density polyethylene, crystalline polypropylene, ethylene-propylene-butene-1 terpolymer as a second component, using a spunbond spinning apparatus and a die according to fiber cross section The fiber was spun. The composite fiber group discharged from the spinneret was introduced into air soccer and drawn and stretched to obtain a composite filament, and then the filament group discharged from the air football was charged with the same charge by a charging device. Thereafter, the fiber bundle was opened by colliding with a reflection plate, and the opened long fiber group was collected as a long fiber web on an endless net-shaped conveyor provided with a suction device on the back surface.

Tables 3 and 4 show Examples 9 to 12 and Comparative Examples 4 and 5, respectively, of the data of the composite fiber and the nonwoven fabric.

[0034]

[Table 4]

[0035]

[Table 5]

In Comparative Example 4, since the composite form was a concentric sheath core, no crimping occurred even when the manufactured nonwoven fabric was subjected to heat treatment, and in addition, no heat bonding occurred between the long fiber layers due to the heat treatment. Was not obtained. Comparative Example 5
As for the second component, the second component was a propylene copolymer having a high fiber surface friction, so that the heat shrinkage was high, but a nonwoven fabric could not be obtained due to poor opening property.

[0037]

The latently crimpable conjugate fiber of the present invention has the following excellent effects by using a propylene copolymer having a copolymerization composition in a specific range as a fiber-forming component of the conjugate fiber. (1) Since the fiber in the web can be latently crimped by heat treatment and can be formed into a nonwoven fabric at the same time, the productivity of the nonwoven fabric is excellent. (2) Since a latent crimp can be developed in the fibers in the web by the heat treatment, a bulky nonwoven fabric can be obtained. In particular, it is possible to apply crimp to a long fiber spun by a spunbond method or a melt blow method, which cannot use a mechanical crimp applying means,
A bulky nonwoven fabric can be obtained. (3) In the case of short fibers, a uniform web can be obtained during card processing by reducing the friction on the fiber surface. In addition, by performing heat treatment on the web to develop crimp, a bulky and well-formed nonwoven fabric can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an eccentric sheath-core composite fiber.

FIG. 2 is a cross-sectional view of an eccentric sheath-core conjugate fiber (with an increased degree of eccentricity).

FIG. 3 is a cross-sectional view of an eccentric sheath-core composite fiber having an irregular core.

[Description of Signs] 1 Second component constituting eccentric sheath-core composite fiber 2 First component constituting eccentric sheath-core composite fiber 3 Second component constituting parallel conjugate fiber 4 Constituting parallel conjugate fiber 1st component 5 2nd component which comprises a conjugate fiber 6 1st component which comprises a conjugate fiber

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4L041 BA02 BA05 BA09 BA22 BA23 BA24 BA32 BA36 BB08 BC05 BD11 CA36 CA37 CA42 CA43 DD01 DD05 DD10 4L047 AA14 AA27 AB09 AB10 BA05 BB02 CA05 CB02

Claims (7)

[Claims] 1. A melting point Tm (° C.) of 120 ≦ Tm ≦ 147
A propylene copolymer comprising 90 to 98% by weight of propylene and 2 to 10% by weight of an α-olefin other than propylene as a first component, and polyethylene as a second component, wherein the first component is The composite form of the second component and the second component is an eccentric sheath-core type in which the second component is arranged on the sheath side, and the area ratio of the first component to the second component in the fiber cross section is 65.
/ 35 to 35/65. 2. The latent roll according to claim 1, wherein the first component is a propylene copolymer comprising 90 to 96% by weight of propylene and 4 to 10% by weight of an α-olefin other than propylene. Shrinkable conjugate fiber. 3. An ethylene-propylene-butene-1 terpolymer comprising 90 to 96% by weight of propylene, 3 to 7% by weight of ethylene and 1 to 5% by weight of butene-1. The latently crimpable conjugate fiber according to any one of claims 1 to 2. 4. The method according to claim 1, wherein the second component comprises at least one selected from high density polyethylene, linear low density polyethylene, and low density polyethylene.
3. The latently crimpable conjugate fiber according to any one of 3. 5. The melting point Tm (° C.) of the first component as the second component.
The latently crimpable conjugate fiber according to any one of claims 1 to 4, which is a polyethylene having a lower melting point. 6. The latently crimpable conjugate fiber according to claim 1, wherein the latently crimpable conjugate fiber is a long fiber. 7. A non-woven fabric using the latently crimpable conjugate fiber according to any one of claims 1 to 6.