JPH1181047A - Thermally splitting conjugate fiber and hot-melt superfine fiber nonwoven fabric using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain hot-melt superfine fiber nonwoven fabric having excellent fabric hand (flexibility and touch) in high yield by using thermally splitting conjugate fiber as the conventional thermally splitting conjugate fibers are not so good in their carding properties. SOLUTION: In the production of thermally splitting conjugate fibers, the main segment 3 having the assembling part 2 formed at the center of the fiber and a plurality of branches 3a-3h radially extending from the assembling part 2 is made of a polypropylene resin, while a plurality of sub-segments 4a-4h divided by the assembling part 2 and the branches 3a-3h are made of polyethylene terephthalate so that the individual parts of the main segments and sub- segments may be exposed to the fiber surface. In addition, the jointing percentage defined as the assembling part to the fiber diameter is set more than 5% and the fineness of the fiber is 1.5-10 deniers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a splittable conjugate fiber and a web and a microfiber nonwoven fabric using the same, and more particularly to a splittable conjugate fiber (hereinafter referred to as "heat splitting property") which is split by mechanical impact and thermal treatment. And a web and a heat-sealed ultrafine nonwoven fabric using the same.

[0002]

2. Description of the Related Art Ultrafine fibrous nonwoven fabrics have a softer touch than ordinary nonwoven fabrics, and their demand is increasing as a surface material for disposable products used for direct contact with the human body, such as disposable diapers and sanitary products. This ultrafine fiber non-woven fabric is generally manufactured using splittable conjugate fibers as material fibers. The split conjugate fibers are mainly split by physical treatment (mechanical impact), and are subjected to mechanical impact and thermal treatment. Can be roughly divided into fibers (thermo-spliable conjugate fibers).

[0003] The heat-dividing conjugate fiber can be split by a heat-sealing facility owned by most nonwoven fabric manufacturers, and can be made into a nonwoven fabric. Therefore, by using a heat-division conjugate fiber as the splittable conjugate fiber, in many cases, it is possible to produce a heat-fused ultrafine fiber nonwoven fabric at low cost without new capital investment. . For this reason, the production of a heat-fused ultrafine fiber nonwoven fabric using the heat-dividing conjugate fiber as a material fiber is rapidly spreading.

[0004] As a heat-division conjugate fiber having the above-mentioned advantages, a specific fiber-forming polymer component B, ie, a specific fiber-forming polymer component B on the outer periphery of a polyolefin component A (for example, a polypropylene resin) when a cross section in the fiber diameter direction is taken, A fiber-forming polymer component B having a melting point difference of 20 ° C. or more from the polyolefin component A and exhibiting incompatibility with the polyolefin component A;
(For example, polyethylene terephthalate)
When the polyolefin component A and the fiber-forming polymer component B have a shape in which the convex portions have a shape provided at intervals or have a cross section in the fiber radial direction, the polyolefin component A and the fiber-forming polymer component B are arranged in the circumferential direction. It has been known to have a multi-layered hollow fiber shape which is alternately distributed along the periphery (all disclosed in Japanese Patent Application Laid-Open No. 2-16 / 1990).
No. 9720).

Japanese Patent Application Laid-Open No. Hei 6-73613 discloses that
A first component composed of a fiber-forming thermoplastic resin (eg, polyethylene terephthalate) having a melting point higher than 130 ° C. and lower than 350 ° C. and a specific thermoplastic resin (eg, a polypropylene-based resin) having a melting point lower than the first component by 20 ° C. or more. (A) and (b) below, which are formed by the second component.

(A) When the cross section in the fiber radial direction is taken, these components are distributed so that the first component is divided into two or more by the second component, and the second component is compounded by heat treatment. A thermally splittable conjugate fiber that separates from fibers into two or more ultrafine fibers, and also splits the first component into two or more ultrafine fibers.

(B) When the cross section in the fiber radial direction is taken, the first component is divided into two or more by the second component, and the first component forms a pool at the center of the fiber. These components are distributed as described above, and the second component is separated from the conjugate fiber by heat treatment to form two or more ultrafine fibers, and the first component becomes one ultrafine fiber without being split, and is a heat-dividable conjugate fiber. .

[0008]

SUMMARY OF THE INVENTION A heat-fused ultrafine fiber nonwoven fabric using a heat-dividing conjugate fiber as a material fiber is provided with a mechanical crimp for imparting a mechanical crimp to the heat-dividing conjugate fiber (after drawing). A carding step of passing the heat-splitting conjugate fiber after mechanical crimping through a carding machine to produce a web, and performing a heat treatment on the web to thermally fuse the fibers constituting the web to form a nonwoven fabric. It is manufactured by performing the non-woven fabric forming step sequentially, but when trying to manufacture a heat-fused ultrafine fiber non-woven fabric using the above-described conventional heat-dividing conjugate fiber as a material fiber, Problems arise.

That is, the above-described conventional heat-division conjugate fiber is easily split by a mechanical impact, and when a sufficient mechanical crimp is applied to the heat-division conjugate fiber, the division proceeds in a mechanical crimp application step. As a result, NEP and cotton loss occur frequently in the carding process, and the card passing property deteriorates.
If the mechanical crimp is weakened in order to suppress the progress of the splitting of the heat-splitting conjugate fiber in the mechanical crimping step, not only the card passing property in the carding step is deteriorated, but also the fibers in the web Since the entanglement is weak, the web is easily broken when the web is transported. Furthermore, heat-dividable conjugate fibers having weak mechanical crimp are unlikely to be split by heat even in a nonwoven fabric forming step.

A first object of the present invention is to provide a heat-splitting conjugate fiber which has a good card passing property and is easy to obtain a heat-fused ultrafine fiber nonwoven fabric excellent in texture (softness and touch). It is in.

A second object of the present invention is to easily produce a heat-fused ultrafine fiber nonwoven fabric which is easy to manufacture with a high yield and excellent in texture (softness and touch). To provide web.

A third object of the present invention is to provide a heat-fused ultrafine fiber nonwoven fabric which is excellent in texture (softness and touch) and can be easily manufactured at a high yield.

[0013]

The heat-splitting conjugate fiber of the present invention, which achieves the first object, contains two components of a polypropylene resin and polyethylene terephthalate. The polypropylene-based resin forms a main segment in a shape having a pool formed at the center of the fiber and a plurality of branches radially extending from the pool toward the fiber surface. Polyethylene terephthalate is respectively distributed to form a plurality of sub-segments separated by the pool and the branch, and
The main segment and the sub-segment are each formed such that a part thereof is exposed to the fiber surface, and a joint portion ratio indicated by a ratio of the pool portion to the fiber diameter is 5% or more, Fineness is 1.5-10d
e.

Further, the web of the present invention that achieves the second object has a heat-dividing conjugate fiber of the present invention as a main material fiber, and has a splitting ratio of 50 to 90.
%.

[0015] In the heat-fused ultrafine fiber nonwoven fabric of the present invention which achieves the third object, the ultrafine fibers generated by splitting the thermally splittable composite fiber of the present invention are used as main material fibers. It is characterized by the following.

[0016]

Embodiments of the present invention will be described below in detail. As described above, the heat-dividing conjugate fiber of the present invention comprises two components of a polypropylene-based resin (hereinafter abbreviated as “PP-based resin”) and a polyethylene terephthalate (hereinafter abbreviated as “PET”). Contains.

Specific examples of the above PP resin include homopolypropylene, ethylene-propylene random copolymer, ethylene-propylene-butene 1 copolymer and the like. Among these PP-based resins, ethylene-propylene is used in order to obtain a heat-division conjugate fiber having a high heat division property and a high fusion strength at the time of fusion when used as a material fiber of the heat-fusion ultrafine fiber nonwoven fabric. Random copolymers are preferred. On the other hand, as the above-mentioned PET, homo PET generally used as a material for synthetic fibers is preferable.

The heat-dividing conjugate fiber of the present invention containing the two components of the PP resin and PET has a pool formed at the center of the fiber when the cross section in the fiber radial direction is taken. The main segment having a shape having a plurality of branch portions radially extending from the portion toward the fiber surface is formed by the above-mentioned PP-based resin, and the plurality of sub-regions separated by the pool portion and the branch portion are formed. As the segments are formed by the above PET,
These components are allocated.

The term "cross-section in the fiber radial direction" used in the present invention means that the cross-sectional shape in the radial direction of the undrawn yarn is substantially similar to the cross-sectional shape in the radial direction of the drawn yarn. It means the cross-sectional shape in the radial direction of the undrawn yarn or drawn yarn. For the same reason, the joint ratio described later means the joint ratio in an undrawn yarn or a drawn yarn.

The above-mentioned pool portion in the main segment formed of the PP-based resin, when a heat-fused ultrafine fibrous nonwoven fabric is manufactured using the heat-dividing conjugate fiber of the present invention, one pool is formed during the manufacturing process. A plurality of PP-based ultrafine fibers (at least one fiber is composed of a branched portion peeled from the above-mentioned pool portion; the same applies hereinafter) is not generated from the heat-dividing conjugate fiber (the heat-dividing conjugate fiber of the present invention). , For joining the plurality of branch portions to each other.

On the other hand, the plurality of branch portions in the main segment are for forming a plurality of sub-segments made of PET in cooperation with the above-mentioned pool portion. The cross-sectional shape of each of the branch portions is not particularly limited, and may be a trumpet shape, a fan shape, or the like.

At this time, it is preferable to select the fiber cross-sectional shape (cross-sectional shape in the fiber radial direction) so that the tips reach the fiber surface for as many branches as possible. It is more preferable to select the fiber cross-sectional shape so as to achieve.
That is, the main segment made of PP resin and PE
It is preferable to select the fiber cross-sectional shape so that each of the sub-segments made of T exposes a part of the fiber to the fiber surface, and the tips of all branches and the tips of all sub-segments reach the fiber surface. It is preferable to select the fiber cross section as described above.

The total number of the branched portions may be 2 or more. However, from the viewpoint of obtaining a heat-splitting conjugate fiber which is easy to obtain a heat-fused ultrafine fiber nonwoven fabric excellent in flexibility and touch, 4 to 8
It is preferable that Along with this, the total number of sub-segments made of PET also becomes 2 or more, and in order to obtain a heat-splitting conjugate fiber that is easy to obtain a heat-fused microfiber nonwoven fabric having excellent flexibility and touch, the total number of sub-segments is Is also preferably 4 to 8. Then, the ratio of the sum of the cross-sectional areas of the sub-segments to the cross-sectional area of the main segment when the cross section in the fiber radial direction is taken ((the former) / (the latter);
Hereinafter, it is abbreviated as “cross-sectional area ratio”. ) Is 70 / 30-40
/ 60 is preferable.

By setting the cross-sectional shape in the radial direction of the heat-dividing conjugate fiber to the above-mentioned shape, it is possible to obtain (1) a division ratio (the heat-dividing conjugate (Division ratio of fiber) is about 50-9
Even if the carding step is performed so as to obtain a 0% web (the web of the present invention), it is possible to obtain a heat-fused ultrafine fiber nonwoven fabric which has good card passing properties and excellent flexibility and touch. Possible, heat-splitting conjugate fibers can be obtained.

However, if the ratio of the pool portion to the fiber diameter of the heat-dividing conjugate fiber is small, one heat-split ultrafine fiber nonwoven fabric is produced by using the heat-dividing conjugate fiber. It is difficult to suppress the generation of a plurality of PP-based ultrafine fibers from the conductive composite fiber, and as a result,
It becomes difficult to obtain a heat-dividing conjugate fiber having good card passing properties.

Therefore, in order to obtain a heat-splitting conjugate fiber which has a good card passage property and is easy to obtain a heat-fused ultrafine fiber nonwoven fabric excellent in flexibility and touch, the fiber diameter of the heat-splitting conjugate fiber is required. Is preferably 5% or more. The joint ratio is more preferably 7 to 50%, particularly preferably 10 to 30%.

However, if the fiber diameter of the heat-splitting conjugate fiber is too small, that is, if the fineness of the heat-splitting conjugate fiber is too small, the heat-splitting conjugate fiber is not affected even if the joint ratio is 5% or more. In the process of manufacturing a heat-fused microfiber nonwoven fabric by using a plurality of PP
It becomes difficult to suppress the generation of ultrafine fibers. Further, if the fiber diameter of the heat-dividing conjugate fiber is too large, that is, if the fineness of the heat-dividing conjugate fiber is too large, one heat-dividing conjugate fiber is produced in the process of manufacturing a nonwoven fabric using the heat-dividing conjugate fiber. Even if the generation of a plurality of PP fibers can be suppressed from the above, the fineness of the PP fibers (comprising the main segment) or the PET fibers generated by the splitting of the thermally splittable conjugate fibers is extremely fine. It is too large to be called a fiber.

Therefore, the fineness of the heat splittable conjugate fiber of the present invention is preferably 1.5 to 10 de, and
It is more preferable to set it to 5.0 de. The fineness of the main segment made of the PP-based resin is preferably 30% to 60% of the fineness of the heat-division conjugate fiber.

When a heat-fusible ultrafine fiber nonwoven fabric is to be manufactured using the heat-divideable conjugate fiber of the present invention having the above-mentioned fiber cross-sectional shape and the above-mentioned joint ratio and fineness as a material fiber, the conventional heat-divided nonwoven fabric is used. As in the case where the conjugate fiber is used as the material fiber, the sub-segment made of PET is separated from the mechanical crimping step to the carding step and peeled and divided mainly in the vicinity of the crooked apex to produce an ultrafine fiber. And further division proceeds in the subsequent nonwoven fabric forming step. However, it is unlikely that the main segment made of the PP-based resin is thinned from the stage of the mechanical crimping step to the step of forming the nonwoven fabric to newly generate ultrafine PP-based fibers.

If the number of mechanical crimps in the mechanical crimping step is approximately 13 to 20 pieces / inch, the staple fiber obtained by cutting the fiber after the mechanical crimping into a predetermined length is obtained. In most cases, an undivided fiber cross-sectional structure is maintained in at least one portion except for a bent vertex generated by mechanical crimping and its vicinity.

According to the study of the present inventors, since the fiber made of PET has a relatively small frictional resistance on the surface, the sub-segment is formed by PET and the sub-segment is mainly used until the carding step. The splitting ratio (the splitting ratio of the heat splittable conjugate fiber of the present invention) is approximately 50 by peeling and splitting from the heat splittable conjugate fiber near the crooked vertex of the crimp.
It has been clarified that even if a web of ~ 90% (the web of the present invention) is obtained, there is substantially no significant adverse effect on card passability. On the other hand, PP
Since the fibers made of resin-based resin have a relatively high frictional resistance on the surface, the presence of a large number of ultrafine fibers made of PP-based resin in the carding process will result in frequent occurrence of NEPs and cotton loss, resulting in poor card passage. Became clear.

In the heat-dividing conjugate fiber of the present invention, as described above, the main segment made of the PP-based resin is thinned from the mechanical crimping step to the carding step to newly generate an ultrafine PP-based fiber. Is unlikely to occur. Therefore, even if the above-mentioned web (the web of the present invention) having a division ratio of about 50 to 90% is to be manufactured, the card passing property is good.

In the heat-dividing conjugate fiber of the present invention, the main segment made of the PP resin functions as a heat-sealing (adhesion) component. Since it is difficult to reduce the thickness during the process, a heat-fused ultrafine fiber nonwoven fabric having high adhesive strength can be obtained.

The heat-fusible ultrafine fiber nonwoven fabric using the heat-division conjugate fiber of the present invention as a material fiber, which greatly contributes to its flexibility and touch, is produced by the above-mentioned heat-division conjugate fiber during the manufacturing process. The sub-segments separated and separated from the fibers, that is, ultrafine fibers made of PET,
As described above, when the thermally splittable conjugate fiber of the present invention is used as the heat-fused ultrafine nonwoven fabric material fiber, the above-mentioned web (the web of the present invention) having a split ratio of approximately 50 to 90% is produced. Even if you try, the card passability is good. Therefore, a heat-fused ultrafine fiber nonwoven fabric excellent in flexibility and touch can be easily obtained with a high yield.

The heat-splitting conjugate fiber of the present invention having such advantages is obtained by appropriately selecting the shape of the split-type conjugate spinneret and the discharge viscosities of the PP resin and PET to obtain a desired undrawn yarn. It can be obtained by stretching an undrawn yarn to about 2 to 5 times, or by cutting it into 2 to 10 cm after drawing to form a staple fiber.

In this specification, the term "division ratio" used for the web or the heat-fused ultrafine fiber nonwoven fabric refers to the thermally splittable conjugate fiber of the present invention used as a material fiber of the web or the heat-fused ultrafine fiber nonwoven fabric. , Calculated by the following equation.

(Equation 1)

Here, Sd, B and F in the above equation
Is to insert a non-woven fabric densely into a polyurethane tube, fill it, cut it perpendicularly to the longitudinal direction of the tube, observe the cross section with a scanning electron microscope (SEM), and obtain an image area of about 50 undivided fibers. The cross-sectional photograph was taken and obtained from this photograph.

Next, the web of the present invention will be described. As described above, the web of the present invention is characterized in that the above-described thermally splittable conjugate fiber of the present invention is used as a main material fiber, and the split ratio of the thermally splittable conjugate fiber is 50 to 90%. It is.

Here, the web of the present invention may be a composite heat-sealable fiber of PP / high-density polyethylene, a composite heat-sealable fiber of PET / high-density polyethylene, polyester in addition to the heat-splitting composite fiber of the present invention. Approximately 70 fibers of rayon, etc.
Materials containing less than wt% may be used as material fibers, but it is more preferable to use only the heat-division conjugate fibers of the present invention as material fibers. Therefore, the term "web in which the thermally splittable conjugate fiber of the present invention is used as a main material fiber" in the present invention means "a web in which the ratio of the thermally splittable conjugate fiber of the present invention is approximately 30 to 100 wt%". It shall be.

The web of the present invention using the above-mentioned material fiber as the material fiber is obtained by applying a mechanical crimp of about 13 to 20 pieces / inch to the material fiber and cutting it into a desired length to form a staple fiber. For the amount, for example, a 360 mm sample roller card, SC-360
It can be obtained by sequentially performing preliminary opening and opening using a card machine such as DR (manufactured by Daiwa Kiko Co., Ltd.).

The card passing property at this time is high as described in the description of the heat-division conjugate fiber of the present invention.
Further, since sufficient mechanical crimp can be provided as described above, breakage during transport is less likely to occur. Furthermore, when the web is made into a nonwoven fabric to obtain a heat-fused ultrafine fiber nonwoven fabric, the heat-dividing conjugate fiber is further divided in the process of forming the nonwoven fabric, so that the texture (flexibility and touch) is excellent. Can be obtained. That is, the web of the present invention has a texture (flexibility and tactile sensation).
It is possible to easily obtain a heat-fused ultrafine fiber nonwoven fabric having excellent productivity under high productivity.

Next, the heat-fused ultrafine fiber nonwoven fabric of the present invention will be described. As described above, the heat-fused ultrafine fiber nonwoven fabric of the present invention is characterized in that the ultrafine fibers generated by the splitting of the thermally splittable conjugate fiber of the present invention are used as main material fibers.

Here, the heat-fused ultrafine fiber nonwoven fabric of the present invention is a PP / high-density polyethylene composite heat-fusible fiber in addition to the ultrafine fibers produced by splitting the heat-division conjugate fiber of the present invention. , PET / high-density polyethylene-based composite heat-fusible fiber, polyester, rayon, etc., may contain approximately 70% by weight or less. It is more preferable that only the resulting ultrafine fibers are used as material fibers. Therefore, the term “heat-fused ultrafine fiber nonwoven fabric having the ultrafine fibers generated by splitting the thermally splittable composite fibers of the present invention as the main material fiber” in the present invention means “the thermally splittable composite fibers of the present invention”. Is a heat-fused ultrafine fiber nonwoven fabric in which the ratio of the ultrafine fibers generated by the division is approximately 30 to 100% by weight. "

The heat-fused microfiber nonwoven fabric of the present invention can be obtained in the same manner as a conventional heat-fused microfiber nonwoven fabric, except that the above-mentioned material fibers are used. From the viewpoint of obtaining a nonwoven fabric, it is preferable to use an embossing roll heat-sealing nonwoven fabric rather than a hot air-sealing nonwoven fabric. At this time, the basis weight of the heat-fused ultrafine fiber nonwoven fabric can be appropriately selected according to the intended use. When trying to obtain a heat-fused microfiber nonwoven fabric used as a surface material for disposable items used in direct contact with the human body, such as disposable diapers and sanitary products, a selection within a range of approximately 15 to 30 g / m ² is generally selected. Is done.

In producing the heat-fused microfiber nonwoven fabric of the present invention, the heat-splitting conjugate fiber of the present invention used as a material fiber is converted into sub-segments, ie, ultrafine fibers of PET, until the carding step. And the splitting ratio of the heat splittable conjugate fiber is approximately 50 to 90.
% As described above, it is possible to obtain a good card passing property as described above.

Therefore, in the mechanical crimping step, sufficient mechanical crimp can be imparted, and ultrafine fibers made of PET which is a fiber component which greatly contributes to the flexibility and touch in the heat-fused ultrafine fiber nonwoven fabric. Can be easily increased. As a result, a product excellent in flexibility and tactile sensation can be easily manufactured with high yield.

[0047]

Hereinafter, embodiments of the present invention will be described.
With respect to the measurement items or evaluation items in each embodiment, the measurement method or evaluation method will be described in advance. 1. Bonded portion ratio The undrawn yarn was put into a pinhole, and a cross section of the undrawn yarn in the fiber diameter direction was photographed using an optical microscope. From the photograph, the diameter X and the fiber diameter Y of the pool shown in FIG. After it was determined, it was calculated from these values. However, when the main segment was formed by PET without forming the main segment by the PP resin, the ratio of the pool occupying the fiber diameter was calculated, and a minus sign was given to this value to obtain the joint ratio. . In FIG. 1, reference numeral 1 denotes a heat-division conjugate fiber, reference numeral 2 denotes a pool, reference numerals 3a to 3h denote branch portions, reference numeral 3 denotes a main segment, and reference numerals 4a to 4h denote sub-segments. Is shown.

2. The number of crimps was determined by the method of JIS L1015. 3. Card Passability A visual evaluation was made based on the following criteria. ：: There is almost no cotton fall or nep, and the web does not break. Δ: Cotton fall or nep occurs slightly frequently. X: Cotton shedding or NEP occurs frequently or the web breaks.

4. Non-woven fabric strength (1) MD non-woven fabric strength The length direction is matched with the direction parallel to the fiber orientation of the non-woven fabric (MD direction), and a measurement sample with a width of 50 mm is cut out.
Orientec Co., Ltd. tensile tester (Tensilon R
It was measured using a TM-250) under the conditions of a distance between chucks of 100 mm and a pulling speed of 50 mm / min. (2) Non-woven fabric strength in the CD direction A length of the non-woven fabric is aligned with a direction perpendicular to the fiber orientation of the non-woven fabric (a direction orthogonal to the CD direction), and a sample for measurement having a width of 50 mm is cut out. The measurement was performed under the conditions of a distance between chucks of 60 mm and a pulling speed of 50 mm / min.

5. Hand (Softness and Touch) A sensory test was conducted by five panelists on the softness and touch of the nonwoven fabric, and the results were evaluated based on the following criteria. ：: Very good. Δ: Good. ×: Somewhat bad.

Example 1 (1) Production of heat-splitting conjugate fiber First, MF was used as a PP resin as a material of the main segment.
An ethylene-propylene random copolymer having an R of 24 (hereinafter abbreviated as “co-PP”; Y, manufactured by Idemitsu Petrochemical Co., Ltd.)
2035G) and PE, which is the material of the sub-segment,
As for T, those having an IV [η] of 0.65 (manufactured by Asahi Kasei Corporation; no product name) were melt-spun under the conditions shown in Table 1, and as shown in Table 1, the cross-sectional area ratio was 50/50. A multilayer joint type composite fiber (undrawn yarn) having a joint ratio of 10% and a fineness of 10.6 de was obtained.

In this conjugate fiber, when the cross section in the fiber diameter direction is taken, a pool formed at the center of the fiber and four branches radially extending from the pool toward the fiber surface are formed. The co-PP is distributed so as to form a main segment having the same shape, and the PET is distributed so as to form four sub-segments separated by the pool portion and the branch portion.

The cross-sectional shape (cross-sectional shape in the fiber radial direction) of each of the four branched portions in the main segment exhibits a trumpet shape extending from the pool portion to the fiber surface, and the tip of each branched portion reaches the fiber surface. . The tip of each sub-segment also reaches the fiber surface.

Next, the above undrawn yarn was drawn 3.6 times to obtain a drawn yarn of 3.5 de. After giving a mechanical crimp of 17 yarns / inch, the yarn was dried and reduced to a fiber length of 44 mm. By cutting, a staple fiber consisting of one of the thermally splittable conjugate fibers of the present invention was obtained.

(2) Production of Web and Heat-Fused Ultrafine Fiber Nonwoven Fabric First, the staple fibers obtained in the above (1) were collected by a conventional method to obtain raw cotton, and the raw cotton was passed through a roller card machine to obtain a web. Table 1 also shows the evaluation results of the card passing property and the splitting ratio of the heat splittable conjugate fiber in the web at this time. Next, the web was formed into a nonwoven fabric by an embossing roll fusing machine heated to 125 ° C. to obtain a heat-fused ultrafine fiber nonwoven fabric having a basis weight of 25 g / m ² . Table 1 also shows the results of the strength and division ratio of the nonwoven fabric measured for the heat-fused microfiber nonwoven fabric and the evaluation results of the texture.

Example 2 (1) Production of heat-dividing conjugate fiber As shown in Table 1, the undrawn yarn was produced under the same conditions as in Example 1 (1) except that the fineness of the undrawn yarn was 6 de. The undrawn yarn was drawn 3.6 times to obtain a 2.0 de drawn yarn. Then, the drawn yarn was given a mechanical crimp of 15 pieces / inch, dried, and cut into a fiber length of 44 mm to obtain a staple fiber comprising one of the heat-division conjugate fibers of the present invention.

(2) Production of Web and Heat-Fused Ultrafine Fiber Non-woven Fabric Under the same conditions as in Example 1 (2) except that the staple fiber obtained in (1) above was used as a material fiber, the basis weight was 24 g / g. A heat-fused ultrafine fiber nonwoven fabric of m ² was obtained. Table 1 also shows the evaluation results and the measurement results of the same items as those evaluated and measured in Example 1 for the card permeability and the web and the heat-fused ultrafine fiber nonwoven fabric at this time.

Example 3 (1) Production of heat-splitting conjugate fiber First, MF was used as a PP resin as a material of the main segment.
An ethylene-propylene random copolymer having an R of 17 (Y2035G (MFR = 24) manufactured by Idemitsu Petrochemical Co., Ltd.) and F744N2 (MFR = 7) manufactured by Idemitsu Petrochemicals Co., Ltd. in a weight ratio of former: latter = 70: 30. Mixture obtained by mixing
Further, as the material of the sub-segment, the same PET as that used in Example 1 was used and melt-spun under the conditions shown in Table 1, and the cross-sectional area ratio was 50/50 as shown in Table 1. A multi-layer composite fiber (undrawn yarn) having a joint ratio of 7% and a fineness of 7.5 de was obtained. The cross-sectional shape in the radial direction of this conjugate fiber is the same as the cross-sectional shape in the radial direction of the conjugate fiber obtained in Example 1 (1). Next, the above undrawn yarn is drawn 3.0 times to obtain a drawn yarn of 3.0 de,
A 13-piece / inch mechanical crimp was applied thereto, followed by drying and cutting to a fiber length of 44 mm to obtain a staple fiber comprising one of the heat-division conjugate fibers of the present invention.

(2) Production of web and heat-fused ultrafine fiber non-woven fabric The same conditions as in Example 1 (2) were used except that the staple fiber obtained in the above (1) was used as a material fiber, and the basis weight was 26 g /. A heat-fused ultrafine fiber nonwoven fabric of m ² was obtained. Table 1 also shows the evaluation results and the measurement results of the same items as those evaluated and measured in Example 1 for the card permeability and the web and the heat-fused ultrafine fiber nonwoven fabric at this time.

Example 4 (1) Production of heat-dividing conjugate fiber As shown in Table 1, the cross-sectional area ratio was 47/53, the joint ratio was 17%, and the fineness of the undrawn yarn was 9 de. An unstretched yarn was obtained under the same conditions as in Example 1 (1) except that the unstretched yarn was stretched 2.7 times to 4.0 de.
Was obtained. Then, the drawn yarn was given a mechanical crimp of 17 pieces / inch, dried, and cut into a fiber length of 44 mm to obtain a staple fiber composed of one of the heat-division conjugate fibers of the present invention.

(2) Production of web and heat-fused ultrafine fiber non-woven fabric Under the same conditions as in Example 1 (2) except that the staple fiber obtained in (1) above was used as a material fiber, the basis weight was 25 g / g. A heat-fused ultrafine fiber nonwoven fabric of m ² was obtained. Table 1 also shows the evaluation results and the measurement results of the same items as those evaluated and measured in Example 1 for the card permeability and the web and the heat-fused ultrafine fiber nonwoven fabric at this time.

Example 5 (1) Production of heat-dividing conjugate fiber As shown in Table 1, the cross-sectional area ratio was 65/35, the joint ratio was 28%, the fineness of the undrawn yarn was 9 de, and the fiber An undrawn yarn was obtained under the same conditions as in Example 1 (1) except that the shape of the main segment when the cross section in the radial direction was taken was a cross shape, and this undrawn yarn was 3.6.
It was drawn twice to obtain a drawn yarn of 3.1 de. Then, after giving a mechanical crimp of 13 pieces / inch to the drawn yarn, it was dried and cut into a fiber length of 44 mm to obtain a staple fiber composed of one of the heat splittable conjugate fibers of the present invention.

(2) Production of web and heat-fused ultrafine fiber nonwoven fabric The same conditions as in Example 1 (2) were used except that the staple fiber obtained in the above (1) was used as a material fiber, and the basis weight was 24 g / m2. A heat-fused ultrafine fiber nonwoven fabric of m ² was obtained. Table 1 also shows the evaluation results and the measurement results of the same items as those evaluated and measured in Example 1 for the card permeability and the web and the heat-fused ultrafine fiber nonwoven fabric at this time.

Comparative Example 1 (1) Production of heat-splitting conjugate fiber First, PET was used as the material of the main segment (the same as that used in Example 1 as the material of the sub-segment)
And an ethylene-propylene random copolymer having an MFR of 24 (the same as that used as the main segment material in Example 1) was melt-spun under the conditions shown in Table 1 As shown in Table 1, the cross-sectional area ratio was 50/50 and the joint ratio was -1.
%, And a multi-layer composite fiber (undrawn yarn) having a fineness of 8 de was obtained. The cross-sectional shape in the radial direction of the conjugate fiber is substantially the same as the cross-sectional shape in the radial direction of the conjugate fiber obtained in Example 1 (1), but the cross-sectional shape of each of the four branched portions in the main segment (in the fiber radial direction) Is a sector shape having an apex angle on the pool side. Next, the above undrawn yarn was drawn 2.7 times to obtain a drawn yarn of 3.6 de.
After giving a mechanical crimp of 3 pieces / inch, it was dried and cut into a fiber length of 44 mm to obtain a staple fiber.

(2) Production of Web and Heat-Fused Ultrafine Fiber Nonwoven Fabric Under the same conditions as in Example 1 (2) except that the staple fiber obtained in (1) above was used as a material fiber, the basis weight was 27 g / A heat-fused ultrafine fiber nonwoven fabric of m ² was obtained. Table 1 also shows the evaluation results and the measurement results of the same items as those evaluated and measured in Example 1 for the card permeability and the web and the heat-fused ultrafine fiber nonwoven fabric at this time.

Comparative Example 2 (1) Production of heat-splitting conjugate fiber First, PET was used as the material of the main segment (same as that used in Example 1 as the material of the sub-segment)
And an ethylene-propylene random copolymer having an MFR of 17 (the same as that used as the main segment material in Example 3) was melt-spun under the conditions shown in Table 1 As shown in Table 1, the cross-sectional area ratio was 50/50 and the joint ratio was -7.
%, And a multilayer bonded type composite fiber (undrawn yarn) having a fineness of 10.6 de was obtained. The cross-sectional shape in the radial direction of this conjugate fiber is the same as the cross-sectional shape in the radial direction of the conjugate fiber obtained in Example 1 (1). Next, the above undrawn yarn was drawn 2.7 times to obtain a drawn yarn of 3.6 de, which was subjected to mechanical crimping of 13 pieces / inch, dried and cut into a fiber length of 44 mm. To obtain staple fiber.

(2) Production of Web and Heat-Fused Ultrafine Fiber Nonwoven Fabric Under the same conditions as in Example 1 (2) except that the staple fiber obtained in (1) was used as a material fiber, the basis weight was 27 g / A heat-fused ultrafine fiber nonwoven fabric of m ² was obtained. Table 1 also shows the evaluation results and the measurement results of the same items as those evaluated and measured in Example 1 for the card permeability and the web and the heat-fused ultrafine fiber nonwoven fabric at this time.

[0068]

[Table 1]

As shown in Table 1, Examples 1 to 5
The heat splittable conjugate fiber of the present invention obtained in each of Examples 1 and 2 has a good card passing property, and the heat-fused ultrafine fiber nonwoven fabric of the present invention obtained in these Examples has excellent texture (softness and tactile sensation). I have. Moreover, despite the fact that the webs of the present invention obtained in Examples 1 to 5 each consist of heat-splitting conjugate fibers to which many mechanical crimps of 13 to 17 pieces / inch are provided. As described above, the card passing property is good. And, as described above, since it is made of the heat-dividing conjugate fiber provided with a large number of mechanical crimps, there was no breakage during transportation. Further, in the subsequent nonwoven fabric forming step, the division of the heat splittable conjugate fiber further proceeds, and a heat-fused ultrafine fiber nonwoven fabric excellent in texture (flexibility and touch) is obtained.

On the other hand, the heat-fused ultrafine fiber non-woven fabric obtained in Comparative Example 1 is excellent in texture (softness and touch), but the heat-splitting conjugate fiber obtained in Comparative Example 1 is used up to the carding step. Among them, a large number of ultrafine fibers (comprising sub-segments) made of a PP-based resin (co-PP) were generated, so that the card permeability was poor. Therefore, it is not possible to obtain a heat-fused ultrafine fiber nonwoven fabric excellent in texture (flexibility and tactile sensation) under a high yield. In addition, the heat-fused ultrafine fiber nonwoven fabric obtained in Comparative Example 2 has a good texture (softness and touch), but the heat-splitting conjugate fiber obtained in Comparative Example 2 also has a good effect until the carding step. In this case, a large number of ultrafine fibers (those comprising sub-segments) made of a PP-based resin (co-PP) were generated, so that the card passing property was not so good. Therefore, it is difficult to obtain a heat-fused ultrafine fiber nonwoven fabric excellent in texture (flexibility and tactile sensation) under high yield by the heat-divided composite fiber obtained in Comparative Example 1 or Comparative Example 2. Further, in any of the heat-fused ultrafine fiber nonwoven fabrics of Comparative Example 1 and Comparative Example 2, the PP resin (c
(o-PP), the strength of the nonwoven fabric is insufficient due to the small fineness of the ultrafine fiber (which was a sub-segment of the heat-division conjugate fiber).

[0071]

As described above, according to the present invention,
As it becomes easy to obtain a heat-fused ultrafine fiber nonwoven fabric with excellent texture (flexibility and touch) at a high yield,
It becomes possible to provide the surface material of disposable articles used for applications that directly touch the human body, such as disposable diapers and sanitary articles, at a lower cost.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining how to determine a joint ratio according to the present invention.

[Explanation of symbols]

1: heat splittable composite fiber, 2: pool part, 3a, 3
b, 3c, 3d, 3e, 3f, 3g, 3h ... branching part, 3 ... main segment, 4a, 4b, 4c, 4d,
4e, 4f, 4g, 4h: sub-segment, X: diameter of pool, Y: fiber diameter.

Claims (4)

[Claims] The present invention comprises a polypropylene resin and a polyethylene terephthalate. The polypropylene resin contains two components, a polypropylene resin and a polyethylene terephthalate. So as to form a main segment having a shape having a plurality of branches radially extending toward the surface;
Further, the polyethylene terephthalate is respectively distributed so as to form a plurality of sub-segments separated by the pool portion and the branch portion, and the main segment and the sub-segment each have a part thereof. The heat is formed so as to be exposed on the surface of the fiber, and the ratio of the joint portion indicated by the ratio of the pool portion to the fiber diameter is 5% or more, and the fineness is 1.5 to 10 de. Splittable conjugate fiber. 2. When a staple fiber is cut by a predetermined length after a mechanical crimp of 13 to 20 pieces / inch is provided, a portion excluding a bent vertex generated by the mechanical crimp and its vicinity is removed. The thermally splittable conjugate fiber according to claim 1, wherein the fiber cross-sectional structure in an undivided state is maintained in at least one place. 3. A web, wherein the heat-splitting conjugate fiber according to claim 1 or 2 is used as a main material fiber, and the splitting ratio of the heat-splitting conjugate fiber is 50 to 90%. 4. A heat-fused ultrafine fiber nonwoven fabric, characterized in that the ultrafine fibers generated by splitting the thermally splittable conjugate fiber according to claim 1 or 2 are used as main material fibers.