JPH10259522A - Thermally adhesive conjugated fiber, nonwoven fabric by using the same and absorbable material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermally adhesive conjugated fiber capable of providing a nonwoven fabric having a high strength and a soft feeling even by a low temperature and high speed heat treatment, excellent in heat-sealing properties and covering properties and useful for a paper diaper, a sanitary napkin, etc., by forming a specific modified structure. SOLUTION: This thermally adhesive conjugated fiber consists of a component A-1 of a high melting point resin comprising a crystalline polypropylene and a component B-2 of one or more kinds of low melting point resins having a melting point lower than that of the component A and selected from a binary copolymer resin of 85-99wt.% propylene and 1-15wt.% ethylene, a binary copolymer resin of 50-99wt.% propylene and 1-50wt.% butene-1, a ternary copolymer resin of 84-98wt.% propylene, 1-10wt.% ethylene and 1-15wt.% butene-1, etc., and has a cross-section of modified structure having branching parts of the component A-1 of the high temperature melting resin, forming strands extending from the center part to outside, and a projecting projection parts of the component B-2 of the low temperature melting resin by connecting to the branching parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-adhesive conjugate fiber having an irregular cross section, and a nonwoven fabric and an absorbent article using the same. More specifically, the present invention relates to a heat-adhesive conjugate fiber having a polyolefin-based irregular cross-section having a low heat treatment temperature in a nonwoven fabric forming process and excellent concealing properties, and a nonwoven fabric and an absorbent article using the same.

[0002]

2. Description of the Related Art Nonwoven fabrics using a heat-adhesive conjugate fiber having a low-melting-point resin as a sheath component and a high-melting-point resin as a core component are preferred for their properties such as texture (tactile sensation) and strength of the nonwoven fabric. It is used as a surface material for sanitary materials. In the case of short fibers, such non-woven fabrics are usually made into a web by using a heat-adhesive conjugate fiber in a carding process or an air-flow opening process, and then the sheath component is melted by a heat treatment or a pressure treatment, so that the fiber entanglement point is reduced. It is produced by fusing. On the other hand, as a typical example of long fibers, a group of long fibers discharged from a spinneret can be easily manufactured by a spunbond method. After the web is accumulated on the top, the sheath component is melted by a pressure treatment, and the web is made by fusing the fiber entanglement points. The method of fusing the fiber entanglement points can be broadly classified into a thermocompression bonding method using a heated embossing roll or the like and a hot air bonding method using a suction band dryer or a suction drum dryer. The nonwoven fabrics produced by the respective methods are called point-bonded nonwoven fabrics and through-air nonwoven fabrics, and are properly used depending on the application.

[0003] Such heat-adhesive (sheath / core) composite fibers include, for example, high-density polyethylene / polypropylene composite fibers (hereinafter abbreviated as HDPE / PP), high-density polyethylene / polyester. -Based composite fiber (hereinafter abbreviated as HDPE / PET), fiber in which a core component made of polypropylene is combined with a sheath component made of a propylene-based copolymer (hereinafter abbreviated as co-PP / PP) [Japanese Patent Publication No. 55-55] -26203, JP-A-2-
91217, JP-A-2-191720]. Among these, in particular, co-PP / P
P has a very high affinity between the sheath component and the core component because both the resin constituting the sheath side and the resin constituting the core side have a propylene component, so that HDPE / PP or HDPE / PET
, The phenomenon that the sheath side and the core side peel off hardly occurs. In addition, the sheath-side component co-PP is superior in heat sealability with other resins as compared with HDPE.
-A nonwoven fabric made of PP / PP has a high utility value because a durable product can be obtained when processed into a disposable diaper or a sanitary product together with a nonwoven fabric and a film made of another resin.

When fabricating a nonwoven fabric using a heat-adhesive conjugate fiber, the texture (tactile sensation) of the nonwoven fabric generally tends to be inconsistent with the strength. Conventionally, nonwoven fabrics for use in sanitary materials have sufficient strength and the production speed needs to be as high as possible. Therefore, nonwoven fabrics are often produced by heat treatment at a relatively high temperature. However, as a recent trend, a softer texture (feel) has been required for nonwoven fabrics used as surface materials for sanitary materials. For this reason, co-PP
Also for nonwoven fabrics made of / PP, the heat treatment temperature is often suppressed in order to obtain a soft feel (tactile sensation), and as a result, there is a problem that the strength of the nonwoven fabric is reduced. For this reason, it is possible to obtain a nonwoven fabric that satisfies the conflicting demands of high strength and soft texture (tactile sensation) for sanitary materials.
-The appearance of a heat-adhesive conjugate fiber of PP / PP is desired.

[0005] The required performance of a nonwoven fabric as a surface material is, for example, when used in disposable diapers and sanitary napkins, yellow coloring due to excretion and urine of infants and red coloring due to menstrual blood of women are used. Since it has a great effect on the feeling, a covering property, which is a function of making these colorings hard to see, is indispensable for a surface material in recent years.
For this reason, as a method of improving the covering property of the conventional nonwoven fabric, there is a method of increasing the whiteness by including a pigment such as TiO _{2 in} the constituent fibers, but the content of TiO ₂ or the like is too large. Then, the whiteness is improved, but the spinnability of the fiber and the processability into a nonwoven fabric are deteriorated, and it is difficult to cut the long fiber into staples, which increases the production cost. Also,
A method of increasing the grammage to improve the concealing property has also been proposed, but this method has problems in weight reduction, compactness, and cost reduction.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a low-temperature
It is an object of the present invention to provide a conjugate fiber having a modified cross-section from which a nonwoven fabric having a high strength and a soft texture even by a high-speed heat treatment, a high heat sealing property and an excellent concealing property can be obtained.

[0007]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, by adopting the following structure, they have obtained a prospect that the intended object will be achieved. The present invention has been completed. (1) A high melting point resin made of crystalline polypropylene
A thermoadhesive conjugate fiber formed from a component and a B component of at least one low-melting resin selected from propylene-based copolymers having a lower melting point. It is an irregular structure in which the A component of the resin forms a branch portion in which the strand extends radially from the center to the outside, and the B component of the low melting point resin forms a protruding portion connected to the branch portion and protruding. Characteristic thermo-adhesive conjugate fiber. (2) Propylene copolymer component is propylene 8
The heat-adhesive conjugate fiber according to item (1), which is a binary copolymer resin of 5 to 99% by weight and 1 to 15% by weight of ethylene. (3) The propylene-based copolymer component is propylene 5
The heat-adhesive conjugate fiber according to item (1), which is a binary copolymer resin of 0 to 99% by weight and butene-1 1 to 50% by weight. (4) The propylene-based copolymer component is propylene 8
4-98% by weight, ethylene 1-10% by weight, butene-1
The heat-adhesive conjugate fiber according to item (1), which is 1 to 15% by weight of a ternary copolymer resin. (5) A short-fiber nonwoven fabric in which fiber intersections of the heat-adhesive conjugate fiber according to any one of (1) to (4) are thermally bonded. (6) A long-fiber nonwoven fabric in which fiber intersections of the heat-adhesive conjugate fiber according to any one of (1) to (4) are thermally bonded. (7) An absorbent article using the nonwoven fabric according to (5) or (6) at least in part.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The crystalline polypropylene used as the component A of the high melting point resin of the conjugate fiber in the present invention is mainly composed of homopolypropylene or propylene, and a small amount of ethylene, butene-1, hexene-1, octene-1 or 4-methylpentene-1. And a crystalline copolymer with an α-olefin having an MFR (230 ° C., 2.16 kg) of 2 to 15
Those having a melting point of 0 or more and a melting point of 158 ° C. or more are preferred. Such a polymer can be obtained by a known method such as a propylene polymerization method using a Ziegler-Natta catalyst.

In the present invention, the propylene-based copolymer used as the component B of the low-melting-point resin of the conjugate fiber comprises propylene as a main component and a small amount of ethylene, butene-1, hexene-1, octene-1 or 4-methylpentene. A crystalline copolymer with an α-olefin such as Ten-1;
(230 ° C., 2.16 kg) 3-50, melting point 120
C. to 158 [deg.] C. and lower than the crystalline polypropylene as the component A is used. Preferred specific examples include 99 to 85% by weight of propylene and 1 to 1 of ethylene.
A propylene / ethylene binary copolymer containing 5% by weight of propylene and a propylene / butene binary containing propylene of 99 to 50% by weight and butene-11 to 50% by weight. A propylene / ethylene / butene-1 terpolymer comprising 84 to 98% by weight of propylene, 1 to 10% by weight of ethylene, and 1 to 15% by weight of butene-1;
Such a copolymer can be obtained by a known method such as an olefin copolymerization method using a Ziegler-Natta catalyst.

If the content of the comonomers (ethylene and butene-1) in the copolymer is less than 1% by weight each, the resulting fibers will be insufficient in thermal adhesion. Also,
When the melting point of the copolymer is out of the above range, the balance of the nonwoven fabric processing speed, the strength of the nonwoven fabric, the texture of the nonwoven fabric, and the like is deteriorated. The cross section of the heat-adhesive conjugate fiber of the present invention is such that the component A of the high melting point resin forms a branch portion in which a plurality of strands radially extend from the center to the outside, and the component B of the low melting point resin.
This is a modified cross-sectional structure in which a protruding portion is formed in which the component is connected to and protrudes from the branch of the A component.

Further, when a part of the low-melting-point resin component constituting the heat-adhesive conjugate fiber is peeled off in the manufacturing process, the number of heat-bonded fiber intersections is reduced, and as a result, the adhesiveness is lowered, which is preferable. Absent. In particular, the conjugate fiber of the present invention has a specific irregular cross-sectional structure, so that it is easy for peeling to occur further. Therefore, it is important to combine the resin components A and B constituting the conjugate fiber. That is, it is necessary that the constituent resin components A and B have good affinity with each other, and do not split even when an external force is applied to the conjugate fiber. One example of a cross section of the heat-adhesive conjugate fiber of the present invention is shown in FIGS. However, it is not limited to the fiber cross section described below.

In the heat-adhesive conjugate fiber (a1) shown in FIG. 1, the A component 1 of the high melting point resin forms a branch portion in which three strands extend radially from the center to the outside, and the low-temperature resin The B component 2 is a conjugate fiber having a protruding portion which protrudes from the longitudinal end of each strand of the branch portion and extends on an extension of the strand.

In the heat-adhesive conjugate fiber (a2) shown in FIG. 2, the A component 1 of the high melting point resin forms a branch portion in which four strands extend radially from the center toward the outside, and the low melting point resin B component 2 is a conjugate fiber in which a protruding portion is formed, which protrudes from a longitudinal end of each strand of the branch portion and extends on an extension of the strand.

In the heat-adhesive conjugate fiber (a3) shown in FIG. 3, component A of the high melting point resin forms a branch portion in which four strands extend radially from the center to the outside, and the low melting point resin B component 2 in the vicinity of the distal end of each strand of the branch portion in a direction intersecting the longitudinal direction of each strand for each strand (in this case, a direction substantially orthogonal to the longitudinal direction of the strand,
Any crossing angle can be adopted. The same applies hereinafter. ) Is a composite fiber consisting of two projections connected and projecting in substantially opposite directions with a strand interposed therebetween. In this case, one of the protruding portions is connected to a position substantially in the vicinity of the distal end of the strand of the branch portion, and the other is connected to a position slightly closer to the base than the distal end of the strand. Of course, both projections may be connected and project in substantially opposite directions across the strand from substantially the same position on the strand.

In the heat-adhesive conjugate fiber (a4) shown in FIG. 4, the A component 1 of the high melting point resin forms a branch portion in which four strands extend radially from the center to the outside, and the low melting point resin B component 2 in the vicinity of the distal end of each strand of the branch portion, in a direction intersecting the longitudinal direction of the strand for each strand (in this case, a direction intersecting at a slightly oblique angle rather than substantially orthogonal). It is a composite fiber consisting of two projections connected and projecting in substantially opposite directions.

The heat-adhesive conjugate fiber of the present invention is similar to that of FIG.
As shown in FIG. 4 to FIG. 4, it has a special irregular cross-sectional structure. That is, the A component of the high melting point resin protrudes outward in a thin strand shape to form a branched skeleton,
The component B of the low-melting resin is partially joined to the branch of the component to form a projection. In other words, the component B has a very thin projection, and most of the surface is exposed except for a part where the component B is joined to the component A. When the composite fiber having such a morphological structure is subjected to a heat treatment, the B component of the low melting point resin receives heat transfer from most of the exposed surfaces, so that the heat transfer from the softened state to the fusion of the B component is extremely high. It will be easier. Particularly, as shown in FIG. 5, the ratio of the exposed surface area to the volume of the low-melting point resin (component B) is remarkably large as compared with the ordinary sheath-core type or other round cross-sections, so that the heat transfer from the exposed surface is faster. The fusion becomes uniform. That is, the low-temperature adhesiveness becomes excellent. This tendency becomes more remarkable as the protrusion of the B component is thinner and the degree of surface exposure is larger.

The superior low-temperature adhesiveness of the present invention means that the heat-adhesive fiber of the present invention has a low temperature of 3 to 4 ° C. or less, as compared with a normal composite fiber having a round cross section as shown in FIG. This means that heat bonding can be sufficiently performed, and uniform fusion bonding can be performed without causing fusion bonding unevenness at fiber bonding points. As a result, the nonwoven fabric obtained by the low-temperature heat treatment using the heat-adhesive conjugate fiber of the present invention has a large amount of voids between the fibers and has a very soft feeling. In addition, since the fibers are reliably thermally fused to each other at the fiber contact points, the nonwoven fabric improves the bonding force as a fiber aggregate and has high strength. On the other hand, as shown in FIG. 5, in order to sufficiently melt the entire sheath component in the core-sheath composite fiber having a general round cross-sectional structure, a higher temperature is required as compared with the case of the composite fiber of the present invention. When heat treatment is performed under such conditions, the strength due to heat fusion is improved, but the core component also approaches the fusion temperature, so that the entire fiber is fused. As a result, the bulkiness is inevitably lost, and the texture (soft touch) of the nonwoven fabric is impaired.

Further, since the heat-adhesive conjugate fiber of the present invention has a multi-leafed structure in which strands extending radially outward from the center portion are branched, reflected light in which incident light is scattered can be seen in a visual field. Become. Therefore, when the heat-adhesive conjugate fiber of the present invention is used as a fabric such as a nonwoven fabric or a woven or knitted fabric, a so-called anti-see-through effect is exhibited, in which the color below the fabric is difficult to see. That is, the concealing property is excellent.

In order to obtain the heat-adhesive conjugate fiber of the present invention, in the case of short fibers, the above-mentioned resins A and B are spun by a known conjugate spinning method using a spinneret plate represented by the above-mentioned fiber cross section. Then, it is stretched and crimped. The A and B components constituting the composite fiber have a composite weight ratio of A component / B component = 3.
The range of 0/70 to 80/20% by weight is preferred. When the B component is less than 20%, the heat adhesion of the obtained fiber is reduced,
It is also difficult to obtain sufficient tensile strength and low-temperature adhesiveness of a nonwoven fabric using this. If the B component exceeds 70%, the thermal adhesiveness of the fiber is sufficient, but the thermal shrinkage of the fiber increases, and the dimensional stability when obtaining a nonwoven fabric tends to decrease. The fineness of the composite fiber is 0.5 to 10.0 d / f,
In addition, a card having a number of crimps of about 3 to 60 peaks / 25 mm has good card passing property and is preferable.

On the other hand, as a representative of long fibers, the above-mentioned resins A and B can be produced by a known spunbonding method using a spinneret plate represented by the above-mentioned fiber cross section. The A and B components constituting the composite fiber preferably have a composite weight ratio of A component / B component = 30/70 to 80/20% by weight. If the B component is less than 20%, the thermal adhesion of the resulting fiber will decrease, and it will be difficult for a nonwoven fabric using the same to have sufficient tensile strength and low-temperature adhesion. If the B component exceeds 70%, the thermal adhesiveness of the fiber is sufficient, but the thermal shrinkage of the fiber increases, and the dimensional stability when obtaining a nonwoven fabric tends to decrease. The fineness of the composite fiber is preferably 0.5 to 10.0 d / f. Moreover, crimping can be given as needed.

The short-fiber nonwoven fabric of the present invention can be obtained by a known method of forming the above-mentioned conjugate fiber into a desired basis weight web using a card machine and forming the nonwoven fabric by a needle punch method, a suction dryer method, or a hot roll method. it can. On the other hand, a typical example of a long-fiber nonwoven fabric can be obtained by a known method for forming a nonwoven fabric by a spun bond method.

Such a nonwoven fabric is useful in the field of disposable diapers or sanitary napkins. When this nonwoven fabric is used for disposable diapers or sanitary napkins,
The single fiber fineness is preferably 0.5 to 10.0 d / f, and the basis weight of the nonwoven fabric is preferably 8 to 50 g / m ² , more preferably 1 to 50 g / m ^2.
0 to 30 g / m ² . If the single yarn is less than 0.5 d / f, it is difficult to obtain stable spinnability at the time of spinning, and it is difficult to obtain a uniform web. If it exceeds 10.0 d / f, the nonwoven fabric becomes coarse, It is not preferable to use this as a surface material because it becomes difficult to touch.
Also, the basis weight is not enough nonwoven tenacity obtained too thin is less than 10 g / m ^2, not practical since the feel of those preferred nonwoven strength is obtained when more than 50 g / m ² becomes poor cost.

[0023]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to only these examples. Various physical properties in the examples described below were measured by the following methods.

Cross-sectional shape maintaining properties: (short fibers) Fifty single yarns after drawing are sampled, the fiber cross section is photographed with an optical microscope photograph, and the A component of the high melting point resin and the low melting point resin of the irregular cross section are taken in one visual field. Excellent if the shape of the connection portion with the B component is maintained at 90% or more, good if maintained at 80% or more, 8
If it is less than 0%, it was evaluated as unacceptable. Excellent was indicated by ○, good was indicated by Δ, and unacceptable was indicated by ×. Table 1 shows the results.

Cross section maintaining property: (long fiber) The cross section of the nonwoven fabric is photographed by an optical microscope photograph, and the fibers other than those subjected to the thermocompression bonding are observed. When the shape of the connection portion with the B component of the low melting point resin was maintained at 90% or more, it was evaluated as excellent. When maintained at 80% or more, it was evaluated as good.
Good was indicated by Δ, and bad was indicated by ×. Table 1 shows the results.

Opacity (whiteness of web) 10 g of a web was sampled and measured with a color difference meter (SM Color Computer, Suga Test Instruments Co., Ltd.). Table 1 shows the results.

Concealment (Brightness / darkness difference of nonwoven fabric) Using a nonwoven fabric made with a strong nonwoven fabric, placing a white tile and a black tile behind the nonwoven fabric, measuring the lightness with a color difference meter, and calculating the lightness / darkness difference (ΔL) as follows: The smaller the contrast calculated from the formula, the higher the concealment property. Table 1 shows the results.

[0028] The difference in brightness _{^{(ΔL) = L * W -L}} * B L * W: brightness when overlaid the non-woven fabric to the white tile L ^* _B: brightness when overlaid the non-woven fabric in black tile

Nonwoven fabric strength: A sample piece having a length of 15 cm and a width of 5 cm is prepared with the machine direction (MD) of the nonwoven fabric as the length direction and the direction (CD) perpendicular to the machine direction as the width direction. Using a tensile tester, gripping distance 10c
m, and the tensile strength was measured at a tensile speed of 10 cm / min.

Nonwoven fabric feeling: A sensory test was conducted by five panelists, and when all were judged to be soft,
A case where three or more persons were judged to be soft was evaluated as good, and a case where three or more persons were judged to lack softness was evaluated as unacceptable.

Heat sealability: From the nonwoven fabric used for measuring the strength of the nonwoven fabric, the machine direction of the nonwoven fabric (M
D) is the length direction and the direction perpendicular to the machine flow direction (C
With D) as the width direction, a sample piece having a length of 7.5 cm and a width of 2.5 cm was cut out and cut out from nonwoven fabrics of the same kind or nonwoven fabrics having a basis weight of about 20 g / m ^{2 made} of polypropylene fibers (2 d / f). A sample piece of 7.5 cm in width and 2.5 cm in width is superimposed on the tip by 1 cm in length, and 3 k
The sample is thermocompression-bonded at a predetermined temperature under a pressure of g / cm ² for 3 seconds, and the peel strength of the heat-sealed portion is measured using a tensile tester at a gripping interval of 10 cm and a pulling speed of 10 cm / min.

Example 1, Comparative Example 1 A binary copolymer consisting of 5% by weight of butene-1 and 95% by weight of propylene and having an MFR of 15 was used as a component B,
A composite spinning apparatus using a crystalline polypropylene (homopolymer) having a FR of 10 as a component A and using a spinneret having a predetermined fiber cross section shown in FIG. 1 (Example 1) and FIG. 5 (Comparative Example 1). As a result, an undrawn yarn having a composite weight ratio of 40/60 (component B / component A) and a single-fiber fineness of 4 d / f was obtained.
Thereafter, the film was drawn 2.4 times with a hot roll at 95 ° C., mechanically crimped with a stuffer box, dried at 90 ° C., and cut to obtain a 2d × 38 mm conjugate fiber. Using this composite fiber, a temperature of 120 ° C. (Example 1), 12
The card method web was heat-treated at a linear pressure of 20 kg / cm and a speed of 6 m / min using a thermocompression bonding device including an embossing roll having a convex area of 24% and a flat metal roll heated to 4 ° C. (Comparative Example 1). Then, a nonwoven fabric having a basis weight of about 20 g / m ² was obtained. Furthermore, when this nonwoven fabric was used as a surface material for an adult diaper, the whiteness,
Although excellent in softness (soft feeling) and excellent in nonwoven fabric strength and heat sealability, Comparative Example 1 was inferior in whiteness, nonwoven fabric strength and heat sealability in Example 1.
Inferior, the difference in suitability for absorbent articles was clear.

Examples 2-3 A terpolymer having an MFR of 15 consisting of 3% by weight of ethylene, 15% by weight of butene and 92% by weight of propylene and having a MFR of 15 was used as a component B, and a crystalline polypropylene having an MFR of 10 was used. FIG. 3 (Example 2) using (homopolymer) as the component A
And using a spinneret having a predetermined fiber cross-section shown in FIG. 4 (Example 3) in the same manner as in Example 1,
A composite fiber of d × 38 mm was obtained. Using this composite fiber, a thermocompression bonding device consisting of an embossing roll having a convex area of 24% heated to a temperature of 120 ° C. (Examples 2 and 3) and a flat metal roll is used, at a linear pressure of 20 kg / cm and a speed of 6 m.
/ And conditions heat-treating the card method web of min, was having a basis weight of about 20g / m ² non-woven fabric.

Comparative Examples 2-3 High density polyethylene having an MI of 19 was used as a component B, and an MFR of 1 was used.
Using crystalline spinneret having a predetermined fiber cross section shown in FIG. 1 (Comparative Example 2) and FIG. 5 (Comparative Example 3) using crystalline polypropylene (homopolymer) of A A 2d × 38 mm conjugate fiber was obtained in the same manner. Using this composite fiber, a nonwoven fabric was prepared under the same conditions as in Example 1 except that the processing temperature was set to 124 ° C. (Comparative Example 2) and 128 ° C. (Comparative Example 3). Comparative Example 2 is an example in which the same spinneret as in the present invention was used and a resin component outside the scope of the present invention was combined.

Comparative Example 4 Polyethylene terephthalate having an IV value of 0.65 was used as a component B,
Using polyethylene terephthalate having an IV value of 0.49 as the component A and using a spinneret having a predetermined fiber cross section shown in FIG. 1 in the same manner as in Example 1, 2d × 38 mm
Was obtained. In this conjugate fiber, the A / B component was peeled and split after stretching, and was not evaluated.

Comparative Example 5 A high-density polyethylene having an MI of 19 was used as a component B, and an IV value of 0.
Assuming that polyethylene terephthalate of No. 49 is an A component, FIG.
2d × 38 mm composite fiber was obtained in the same manner as in Example 1 by using a spinneret having a predetermined fiber cross section shown in FIG. In this conjugate fiber, the A / B component was peeled and split after stretching, and was not evaluated.

Example 4, Comparative Example 6 A binary copolymer comprising 15% by weight of butene-1 and 95% by weight of propylene and having an MFR of 15 was used as a B component.
A composite fiber group discharged from a spinneret having a predetermined fiber cross-section shown in FIG. 1 (Example 4) and FIG. 5 (Comparative Example 6) using crystalline polypropylene (homopolymer) having an FR of 10 as an A component. Was introduced into an air soccer and drawn and stretched to obtain a composite filament.Then, the filament group discharged from the air soccer was charged with the same charge by a charging device and charged, and then collided with a reflecting plate. The opened long fiber group is collected as a long fiber web on an endless net-shaped conveyor provided with a suction device on the back surface. The collected long fiber web is conveyed while being placed on an endless conveyor, and is heated to a temperature of 120 ° C. by using a thermocompression device composed of an emboss roll having a convex area of 24% and a flat metal roll, and has a linear pressure of 20 kg / mm. cm, and heat treated under the conditions of speed of 30 m / min, it was a basis weight of about 20 g / m ² non-woven fabric.
Furthermore, when this nonwoven fabric was used as a surface material for an adult diaper, Example 4 was excellent in whiteness and softness (softness), and also excellent in nonwoven fabric strength and heat sealability. About 6, the whiteness was inferior, and the nonwoven fabric strength and heat sealability were inferior to those in Example 4,
The difference in suitability for absorbent articles was clear.

<< Nonwoven fabric strength, nonwoven fabric feeling, light / dark difference and heat sealability of nonwoven fabric >>
Good (△) or more samples are evaluated. The short-fiber nonwoven fabric was carded at a speed of 20 m / min with a roller card machine at a speed of 20 m / min to obtain a web having a basis weight of about 20 g / m ² . Subsequently, it was processed into a nonwoven fabric at the same speed and at a predetermined temperature using an embossing roll having an adhesion area ratio of 24%. Table 1 shows the results of the respective physical properties. On the other hand, long-fiber nonwoven fabrics
It was manufactured by a spun bond method. A web having a basis weight of about 20 g / m ² was processed into a nonwoven fabric at a predetermined temperature using an embossing roll having a bonding area ratio of 24%. Table 1 shows the results of the respective physical properties.

[0039]

[Table 1]

[0040]

According to the heat-bonding conjugate fiber having an irregular cross-section of the present invention, a nonwoven fabric having a strong nonwoven fabric can be produced by heat treatment at a low temperature for a short time. Further, the nonwoven fabric using the heat-adhesive conjugate fiber has a soft feel. In addition, it has good heat sealability at low temperatures with respect to other polyolefin-based nonwoven fabrics, and also has excellent concealing properties. Such a nonwoven fabric is useful in fields such as disposable diapers and sanitary napkin surface materials.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating the shape of a heat-adhesive conjugate fiber of the present invention.

FIG. 2 is a cross-sectional view illustrating the shape of the heat-adhesive conjugate fiber of the present invention.

FIG. 3 is a cross-sectional view illustrating the shape of the heat-adhesive conjugate fiber of the present invention.

FIG. 4 is a cross-sectional view illustrating the shape of the heat-adhesive conjugate fiber of the present invention.

FIG. 5 is a cross-sectional view showing the shapes of the heat-adhesive conjugate fibers of Comparative Examples 1, 3, and 6.

[Explanation of symbols]

 a1 Heat-adhesive conjugate fiber of the present invention a2 Heat-adhesive conjugate fiber of the present invention a3 Heat-adhesive conjugate fiber of the present invention a4 Heat-adhesive conjugate fiber of the present invention a5 Heat-adhesive conjugate fiber of Comparative Examples 1, 3, and 6 1 High melting point resin (A component) 2 Low melting point resin (B component)

Claims (7)

[Claims] 1. A thermal bonding formed from component A of a high melting point resin made of crystalline polypropylene and component B of at least one type of low melting point resin selected from a propylene copolymer having a lower melting point. The composite fiber has a cross-section where the component A of the high-melting resin forms a branch where the strand extends radially from the center to the outside, and the component B of the low-melting resin connects to the branch. A heat-adhesive conjugate fiber having a deformed structure in which a protruding projection is formed. 2. The heat-adhesive conjugate fiber according to claim 1, wherein the propylene-based copolymer component is a binary copolymer resin of 85 to 99% by weight of propylene and 1 to 15% by weight of ethylene. 3. The heat-adhesive composite according to claim 1, wherein the propylene-based copolymer component is a binary copolymer resin of 50 to 99% by weight of propylene and 1 to 50% by weight of butene-1. fiber. 4. The propylene-based copolymer component is a ternary copolymer resin comprising 84 to 98% by weight of propylene, 1 to 10% by weight of ethylene, and 11 to 15% by weight of butene-11. The heat-adhesive conjugate fiber according to the above. 5. A short-fiber nonwoven fabric in which fiber intersections of the heat-adhesive conjugate fiber according to claim 1 are thermally bonded. 6. A long-fiber nonwoven fabric in which the fiber intersections of the heat-adhesive conjugate fiber according to claim 1 are thermally bonded. 7. An absorbent article using the nonwoven fabric according to claim 5 at least in part.