JPH0696809B2 - Heat-fusible composite fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a composite shape of two kinds of polymers of polyolefin and crystalline polyester or polyamide having a melting point of 150 ° C. or higher, which is substantially in the longitudinal direction of the fiber. Even though they have the same shape, they are randomly different among the single fibers, and the single fibers have a composite shape in which one component forms a layered divided layer and one component forms one independent island component. A new heat having a natural mottle and soft soft texture similar to natural fiber, in which a composite shape and a composite shape in which two components are unevenly distributed form a laminated structure are mixed. The present invention relates to a fusible composite fiber and a method for producing the same.

(Prior Art) A heat-adhesive fiber for producing a nonwoven fabric or the like by heat fusion between fibers is known. For example, polyethylene-polypropylene composite fiber having polyethylene as an adhesive component, polypropylene composite fiber having copolymer nylon as an adhesive component,
Alternatively, there is a composite fiber with polyethylene terephthalate having an ethylene-vinyl alcohol copolymer as an adhesive component.

In particular, recently, baby diapers and diaper liners, sanitary materials such as sanitary products, counter cloths for the food service industry, non-hygienic materials such as drainers for kitchen utensils, base cloths and fixing sheets for shipping medicine, surgery for hospitals. Nonwoven fabrics have been widely used in medical fields such as clothes and masks.

At the same time, demands for texture such as softness and feel have increased as well as functionality such as original handling. Particularly in recent years, the role of synthetic fibers represented by polyethylene terephthalate in the field of non-woven fabrics has increased, and they have been widely used. However, although it has reached a certain level of satisfaction in terms of production efficiency and durability against various consumption performances, it is still insufficient in terms of texture and has a certain degree of softness and human skin during the process of use. It has become necessary to have a texture that is easy to get used to. As for the non-woven fabric made of heat-fusible fibers, it has been strongly desired that not only the functionality but also the texture such as softness is strongly desired, but the present situation is that none is sufficient.

(Problems to be Solved by the Present Invention) Therefore, the present invention has a soft texture similar to natural fibers and a random natural randomness between single fibers as compared with conventional nonwoven fabrics made of heat-fusible fibers. The present invention has been achieved as a result of extensive studies aimed at obtaining a non-woven fabric made of a heat-fusible fiber having a good texture and giving unevenness. That is, the present invention has clarified what kind of material is used, what kind of constitution and conditions should be used for obtaining the above fiber.

(Means for Solving the Problems) The present invention comprises a polyolefin (A polymer) and a crystalline polyester or polyamide having a melting point of 150 ° C. or higher (two polymer components of B polymer), and has a composite shape of A component and B component. Are substantially the same shape in the length direction of the fiber, but are randomly different among single fibers, and one component forms a layered divided layer and one component is an independent island component. Fibers of a composite shape that forms a composite shape and a composite shape of a composite shape similar to a kind of a laminated structure in which two components are unevenly distributed are randomly formed, and A
The heat-fusible composite fiber is characterized in that the contact length at the interface between the component and the B component satisfies a certain condition.

Examples of the polyolefin of the component A polymer referred to in the present invention include polyethylene, polypropylene, poly-4-methylpentene-1 and polyolefin containing these as the main components, or various copolymer-modified polyethylene and various copolymer-modified polypropylene. For example, ethylene-vinyl acetate copolymer is one of the polymers suitable for obtaining the target fiber of the present invention. Since polyolefin, which is the component A, plays a role of acting as a heat-fusible component, it is necessary to select the type of polyolefin in consideration of the melting temperature, flowability, etc., in accordance with the desired adhesive temperature and adhesive strength. is there. For example, even when polyethylene is used, low density polyethylene (LDP
E), high-density polyethylene (HDPE), or linear low-density polyethylene (LLDPE) obtained by copolymerizing ethylene with butene-1, octene-1, etc., should be appropriately selected.

The crystalline polyester or polyamide having a melting point of 150 ° C. or higher as used in the present invention may be any polymer having good fiber-forming properties, preferably polyethylene terephthalate or polyethylene containing polybutylene terephthalate as a main component, or nylon. Polyamide having 6 or nylon 66 as a main component is preferable.

Examples of polyethylene include terephthalic acid, isophthalic acid, naphthalene 2,6-dicarboxylic acid, phthalic acid, α, β- (4-carboxyphenoxy) ethane, 4,
Aromatic dicarboxylic acids such as 4-dicarboxyphenyl, 5-sodium sulfoisophthalic acid or aliphatic dicarboxylic acids such as adipic acid and sebacic acid or their esters, and ethylene glycol, diethylene glycol, 1,4 butanediol, neopentyl Glycol,
A fiber-forming polyester synthesized from a diol compound such as cyclohexane-1,4-dimethanol, polyethylene glycol, or polytetramethylene glycol, in which 80 mol% or more, particularly 90 mol% or more of the constituent units are polyethylene terephthalate units. Alternatively, polyester which is a polybutylene terephthalate unit is preferable. Further, the polyester may contain a small amount of additives, fluorescent brightening agents, stabilizers, ultraviolet absorbers and the like.

The polyamide is a polyamide containing nylon 6, nylon 66, and nylon 12 as the main component, and a small amount of the third
Polyamide which breaks the components may be used. These may contain a small amount of additives, fluorescent whitening agents, stabilizers and the like.

Needless to say, when importance is attached to the morphological stabilizer of the adhesive fiber, it is a matter of course that the B component polymer needs to use a thermoplastic polymer having a melting point higher than the adhesive treatment temperature.

Next, the characteristics of the fiber of the present invention will be described with reference to actual photographs. FIG. 1 shows an example of a photograph showing the cross-sectional structure of the fiber of the present invention. FIG. 2 shows, as an example, a model diagram of a typical one having a typical cross-sectional shape.

The one shown in FIG. 1 uses high-density polyethylene as the A component and polyethylene terephthalate as the B component,
It is spun at a weight ratio of 50:50. The composite shape of the A component and the B component may be randomly different among the single fibers, and the A component may form a layered divided layer, or may form an independent island component. As shown in Figure (a), A
In some cases, the component and the B component are extremely knitted to form a composite shape similar to a laminated structure, and it can be seen that a multifilament is formed in a mixed state. Due to the mixture of these various composite shapes, some have a shrinkage strain difference due to the strain difference between the A component and the B component. For example, in the case of FIG. When it is made into a product, a coil crimp that does not aggregate and has a phase different from that of other monofilaments is developed, which brings about bulkiness.
In the case of, some peeling occurs at the interface between the A component and the B component,
In the final fiber product, fibril-like ultrafine fibers are randomly generated from the surface layer of the single fiber in a branch shape, which is a point to give a soft feeling to the touch. Further, in the case of the fiber forming the shape of FIG. 2 (c), since one component has several island-shaped independent layers having a relatively large size, it cannot be obtained as a complete core-sheath fiber. Brings the natural softness of. In this way, the composite shapes among the single fibers are randomly different, and the shapes are represented by the model shapes shown in FIGS. 2 (a), (b), and (c). For the first time, it was possible to develop similar natural spots and textures, in particular, bulkiness, softness when touched, and overall softness as a fiber assembly. A method for obtaining fibers having such a composite shape will be described in detail later. However, by producing a fiber assembly having the above-described composite shape, a natural natural fiber-like feel that has never existed is exhibited for the first time. It was possible to make it possible.

Further, as the heat-fusible fiber, it is natural that the strength after the production of the non-woven fabric is an important point, so as an example, FIG. 1 shows a polyethylene-to-polyethylene terephthalate ratio of 50:50. However, in order to further improve the adhesive strength, it is preferable to increase the ratio of the heat-fusible polymer. The composite ratio should be changed according to the purpose. It goes without saying that the polyethylene ratio should be set to 50% or more if a higher-strength non-woven fabric is intended.

Further, the average value x of the contact length at the interface between the A component and the B component in the fiber cross section is expressed by the following formula with respect to the average circumferential length y of the fiber cross section.
A major feature is that it is represented by the relationship shown in (1) or (2).

(A and b are the weight percentages of A polymer and B polymer respectively) The ratio of the average perimeter y of the single fiber cross section and the average contact length x at the interface between the A component and the B component is It is a major feature that it exists as a mixture of fibers having a very large distribution and a composite state distributed over a wide range. For example, if the weight ratio of A component and B component is 1: 1,
Explaining with a model, x / y is about 0.3 to 0.4 in the bonded cross section as shown in Fig. 6 (d), and there are 5 layers of A component and B component as shown in Fig. 6 (e). X / y is about 1.08 to 1.10 in the cross section forming the layer, and x / y is about x / y in the cross section forming 10 layers as shown in Fig. 6 (f).
y is about 1.8 to 2.1. On the other hand, the fiber of the present invention has a small x / y of 0.50, and a large x / y of about 4.0 exists, and the contact interface between the two components is small to large. It was found that fibers having various composite shapes were mixed in a very wide range. Distributing in a wide range from small x / y to large x / y is a major feature, and is a major factor for the fibers of the present invention to exhibit natural spots and a soft feel similar to natural fibers. It is considered to be in progress.

The contact lengths of the A component and the B component in the fiber cross section were measured by randomly sampling 100 single fibers and measuring the contact lengths of A and B, and shown as the average value. The specific measurement of the contact length can be obtained by image analysis by a computer for accurate measurement, but simply, the fiber cross-section photograph is magnified at a high magnification, and a grid is placed on the two components. This can be done by reading the number of the squares on the boundary line, or by rotating the running gear on the curve of the two-component boundary line using a map media. Numerical values in the examples described in the present invention are explained by numerical values measured using a map media.

Next, a production example of the fiber of the present invention will be described. In order to develop the composite-shaped fiber structure of the present invention, the two-component polymers of A polymer and B polymer are non-uniformly mixed during spinning, and the non-uniform mixed polymer flow is distributed to each nozzle hole in a different state. It is important that the spinning is performed, but an example of the spinning method is shown in FIGS. 3 and 4. Spinning may be performed using the composite spinneret device as shown in FIGS. 3 and 4. The A polymer and B polymer polymer melt streams extruded by different melt extruders were separately weighed by a predetermined amount by a weigher, filtered by a filter section 8 of the sandbox 1, and then passed through filters 6 respectively. ,
After mixing in a static mixer 5 provided in the mixing plate 2 under a predetermined condition and radial distribution through the distribution passage 7 of the distribution plate 3, the circumferential groove 9 is filled with the polymer, and then the die plate is formed. Spinned from 10.

Here, it is very important to properly select the number of mixing elements of the static mixer 5 so that the two-component polymer is in a non-uniform mixed state. There are several types of static mixers that are currently in practical use. For example, a static type of Kenics is a type that divides into 2 ⁿ layers when passing n elements arranged by rotating blades rotated 180 ° left and right by 90 °. When using a mixer, the number of elements must be within the range of 3-8. More preferably, the range of 4 to 6 is optimal when the die plate has a circular hole arrangement. When it is 8 elements or more, the mixing property of the A polymer and the B polymer becomes too good, and the mixing becomes nearly uniform, and it becomes difficult to express the desired fiber structure by forming fibers.

Even if the number of elements is set to an appropriate number, if the residence time from the start of contact between the two component polymers and the time when they are discharged from the nozzle holes is too long, the reaction between polyester and polyamide tends to proceed and the viscosity decreases during spinning. Is not preferable because of the increased coloration. Discharging is preferably performed within 5 minutes after the contact between the both component polymers, and more preferably within 3 minutes. To reduce the residence time,
The polymer channel of the distribution plate 3 needs to be an appropriate space.

Another important thing to obtain the fiber of the present invention is that the structure of the distribution plate 3 is very important. Fig. 3 Fig. 4 is a detailed view of the distribution plate seen from the XX 'plane of Fig. 3. What is important in this distribution plate is that the two-component polymer flows out in a multilayer state through the static mixer. This is to divide the mixed flow by the number of radial distribution paths to divide the non-uniform mixed flow radially. It is necessary to make the number of distribution channels smaller than the number of nozzle holes. Preferably, the ratio of the number of distribution channels to the number of nozzle holes should be in the range of 1: 1.5 to 1: 5. The example shown in FIG. 4 is an example in which 12 distribution paths are set for 24 hole nozzles.

The non-uniform mixed state flow of the two-component polymer when discharged from the static mixer through the distribution passage through the nozzle hole will be described in more detail as a model. For example, the two-component polymer flow through the four-element static mixer is As shown in FIG. 5, a layered polymer flow of a total of 16 layers of 8 layers of A component and 8 layers of B component is formed, and when the polymer stream is passed through a distribution plate having 12 distribution channels as shown in FIG. To (1) to (12)
Distributed in the state of polymer flow of (1), (12)
Blocks (6) and (7) have extremely few layers,
(3), (4), (10), and (9) have the largest number of layers, and (2), (5), (8), and (11) have intermediate states, and the nozzle upper circumferential groove To After that, when two or more nozzle holes are arranged in each block, the polymer flows from both blocks into the nozzle holes existing at the boundary of the blocks, and (1), (12), (6), ( 7) and (3),
Since the difference in the mixed state with (4), (9), and (10) is further expanded and ejected, the result is shown in FIG. 2 (a) (b).
Thus, a fiber having a complex shape in which the single fibers of (c) are complicatedly different can be obtained.

From (1), (6), (7), and (12) blocks, fibers having a composite shape similar to (a) or (b) are mainly expressed, and (3), (4), (9) ), (10) Block mainly develops a fiber having a complex shape centered on (C), and (2), (5), (8), (10) Block mainly (B). It is possible to obtain a fiber in which a composite shape centered on (a) and a composite shape similar to (a) or (c) are slightly mixed.

However, since the flow of the polymer stream in the time direction constantly flows in the same mixed state, the composite shape having substantially the same shape is maintained in the fiber length direction.

When using a static mixer manufactured by a company other than Kenix, 2 ⁿ
It goes without saying that it is necessary to use a mixer having the number of elements corresponding to the number of layers or more. Toray's Hi-Mixer and Charless &Ross's Los ISG mixers
Since the number of layer divisions when passing n elements is ⁴ⁿ layer divisions, it is preferable that the number of elements is 2 elements or more and 4 elements or less.

The composite ratio of A polymer and B polymer should be in the range of 15:85 to 85:15. 15% by weight of either component
If it is less than the above range, the aggregated state of the components having a small ratio becomes small, and even if the composite shape is close to the intended composite shape, the fiber is not so expressed, which is not preferable. A vs B
In the range of 15:85 to 85:15, it is desirable to comprehensively judge the desired feel, processability, thread physical properties, and strength after creating the heat-adhesive non-woven fabric, and select the optimum mixing ratio. .

The fiber of the present invention is also used as a fusion-bonded fiber aggregate consisting of only the conjugate fiber of the present invention, but 10% by weight of the fiber is used.
It is also used as a mixed and fusion-treated fiber assembly containing other fibers.

Fiber aggregates that are particularly cut into 20 to 100 mm are suitable as non-woven fabric binders for dry use, and those that are cut into 3 to 10 mm are suitable as non-woven fabric binders for wet use, and until now a non-woven fabric having a soft texture is obtained. You can

The fusion treated fiber assembly according to the present invention is useful for a wide variety of non-woven fabrics for various applications, and specific applications are, for example, sanitary material applications.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto. The softness of the non-woven fabric in the examples was determined by the JIS L1085-5-7 bending resistance 45 ° cantilever method described below.

That is, 5 cm of 2 cm x 15 cm test pieces are vertically and well sampled in five directions, and the short side is scaled by a cantilever type tester on a smooth horizontal table with a 45 ° end surface. After placing it in line with the baseline, slide the test piece gently in the direction of the slope, and when the center of one end of the test piece contacts the slope, read the position of the other end of the test piece using a scale.
Bending is indicated by the extruded length of the block (mm),
The front and back of each of the five sheets are weighed, and the average value in each of the vertical and horizontal directions is shown.

The measurement sample is prepared by making a measurement sample 2 denier 51 mm raw cotton, making a web with a basis weight of 30 g / m ² , and then making a non-woven fabric by hot air treatment at the melting point of the component A polymer plus 30 ° C. did.

When mixing other fibers, as a typical example,
A normal polyethylene terephthalate fiber was mixed at a mixing ratio of 50% and a heat-fusible fiber was mixed at a mixing ratio of 50% to prepare a web having a basis weight of 30 g / m ² , and then hot air treatment was performed to prepare a non-woven fabric for measurement.
The cantilever value was about 95 mm for the non-woven fabric in which 50% of the polyethylene-terephthalate fiber and 50% of the core-sheath type heat-fusible fiber of which the sheath component was high-density polyethylene core component was polyethylene terephthalate. The smaller the cantilever value, the softer the nonwoven fabric can be judged to be.

For the swelling property of non-woven fabric, see JIS L1 below.
The thickness was measured by the method 085-5-1.

That is, the thickness (mm) of five different points of the sample was measured by using a thickness measuring machine under a pressure of 20 gf / cm ² for a certain period of time (10 seconds), and the average value is shown. A non-woven fabric was prepared by the method described above, and the measurement was made. A core-sheath type heat-fusible fiber having a normal polyethylene terephthalate fiber 50%, a high density polyethylene sheath component and a polyethylene terephthalate core component at a ratio of 50%. Basis weight 30 which was mixed and heat-sealed
In the case of non-woven fabric of g / m ^2, the thickness was about 0.16 mm. It can be said that the thicker the bulge, the greater the swelling, and the nonwoven fabric is suitable for the purpose of the present invention.

[Example 1] High density polyethylene as A polymer (Mitsubishi Kasei Co., Ltd.)
Manufactured by Yukaron Hard JX-10) and used as B polymer with intrinsic viscosity [η] 0.68 phenol / tetrachloroethane 1:
Polyethylene terephthalate measured at 1, 30 ° C. was used. Each of them is melt-extruded by separate extruders, weighed by gear pumps so that the ratio of A to B becomes 50: 50% by weight, and then supplied to the spinning pack, and then the spinning pack is fed by the device shown in FIG. A four-element static mixer manufactured by Kenitki Co., Ltd. was used to form a layered divided polymer stream of component A and component B, which was passed through a distribution plate having 12 distribution passages, and then at a mouth temperature of 290 ° C. from a 24-hole nozzle. It was discharged and melt-spun at a winding speed of 1000 m / min. The obtained spinning atoms are drawn 3.5 times in a 75 ° C water bath, then 5% shrinkage is applied in a 95 ° C water bath, mechanical crimping is then applied, and then a general oil agent is adjusted to 0.1 wt%. It was applied, subjected to relaxation heat treatment at 100 ° C. for 30 minutes, and then cut into a length of 51 mm to obtain a single yarn denier 2 raw cotton.

A mixture of 50% of the obtained raw cotton and 50% of ordinary polyethylene terephthalate raw cotton (single fiber 2 denier, cut length 51 mm), 100% of the raw cotton, and a basis weight of 30 g / m ² respectively
The web was prepared, and then hot air treatment was performed at 150 ° C. to prepare a non-woven fabric. In all cases, the processability from spinning to final nonwoven fabric production was good and there was no problem. In all cases, the texture of the non-woven fabric was good with natural softness and touch.

[Comparative Example 1] High-density polyethylene (Mitsubishi Kasei Yucaron Hard JX-10) was used as the A polymer, and intrinsic viscosity [η] 0.68 phenol / tetrachloroethane 1: 1 at 30 ° C as the B polymer.
The polyethylene terephthalate measured in 1. was used. Each is melt extruded in a separate extruder and the ratio of A to B is 50
Each of them was weighed with a gear pump so as to be 50% by weight, and then supplied to a spinning pack, and then A polymer was added as a sheath component,
The polymer flow is controlled in the pack by a conventional method so as to form a core-sheath type composite shape in which the B polymer is the core component.
It was discharged from a round hole nozzle at a hole temperature of 290 ° C and melt-spun at a winding speed of 1000 m / min. 75 spinning atoms obtained
Stretching 3.5 times in a water bath at ℃, then shrinking 5% in a water bath at 95 ℃, mechanical crimping, then add a general oil agent to 0.1 wt%, and at 30 ℃ at 100 ℃ It was subjected to a relaxation heat treatment for 1 minute and then cut to a length of 51 mm to obtain a single yarn denier 2 raw cotton.

50% of the obtained raw cotton and 50% of ordinary polyethylene terephthalate raw cotton (single fiber 2 denier, cut length 51 mm) were mixed and made of 100% raw cotton, and a web having a basis weight of 30 g / m ² was prepared. A non-woven fabric was prepared by hot air treatment at 150 ° C. In each case, the obtained nonwoven fabric was inferior to Example 1 in both softness and bulkiness.

[Examples 2 to 7] The same polymer as in Example 1 was used, Example 2 was performed at a composite ratio of A / B of 30/70, Example 3 was performed at A / B 70/30, and the other examples were performed. It carried out on the same conditions as. In Examples 4 and 5, the number of elements of the static mixer was changed to 3 and 7, and the other conditions were the same as those of Example 1. In the sixth embodiment, the number of distribution of the distribution plate is set to 8 and the round hole nozzle of 24 holes is used.
The number of distribution of the distribution plate was set to 8 and the operation was carried out by one round nozzle of 36 holes. Other than that, Example 1 was carried out under the same conditions. As a result, a good nonwoven fabric having good processability was obtained.

[Examples 8 and 9] In Example 8, polybutylene terephthalate (Novadol 500 g manufactured by Mitsubishi Kasei) was used as the B polymer, and in Example 9, nylon-6 (manufactured by Ube Industries) was used as the B polymer.
1013BK) and other conditions were the same as in Example 1.

In each case, a good nonwoven fabric having good processability was obtained.

[Example 10] Polypropylene (K-100 manufactured by Chitsso Co., Ltd.) was used as the A polymer.
A non-woven fabric was prepared under the same conditions as in Example 1 except that 8) was used. At this time, the heat-bonding treatment was carried out under hot air of 200 ° C. A good non-woven fabric having good processability was obtained.

[Example 11] As the A polymer, an ethylene-vinyl acetate copolymer polymer (Evaflex P-140 manufactured by Mitsui Polychemical Co., Ltd.)
A non-woven fabric was prepared under the same conditions as in Example 1 except that the above 5) was used. A good non-woven fabric having good processability was obtained.

[Comparative Examples 2 and 3] The same polymer as in Example 1 was used, Comparative Example 1 had an A / B composite ratio of 10/90, and Comparative Example 2 had an A / B composite ratio of 90/10.
Other conditions were the same as in Example 1, but in all cases, there was a large amount of skew and screw drop during nozzle discharge, and the spinnability was poor. The composite shape of the obtained fiber was close to a sea-island structure and was an ordinary composite shape. The obtained non-woven fabric also had no characteristics.

[Comparative Example 4] The same polymer as in Example 1 was used, and 2 elements were used for the static mixer. The spinnability and the post-processability were good, but the composite shape was randomly different among the single fibers aimed at by the present invention, and one component formed an independent island component, and the layered divided layer was formed. It was not enough to randomly form the formed fiber and the bonded structure in which the two components are unevenly distributed, in the mixed state of the fibers. Moreover, the obtained non-woven fabric was also one with little feature.

[Comparative Example 5] The same polymer as in Example 1 was used, and 12 elements of the static mixer were used. Although the fiberizing processability was good, most of the composite shapes had a sea-island structure. Moreover, the obtained non-woven fabric was also one having little feature.

The conditions and results of each of the above Examples and Comparative Examples are summarized in Table 2.

(Effects of the present invention) As described above, the present invention performs a composite spinning of two kinds of polymers, ie, a polyolefin satisfying a specific condition and a crystalline thermoplastic resin having a melting point of 150 ° C. or more by a method satisfying a predetermined condition to obtain a composite shape. Although it has substantially the same shape in the length direction of the fiber,
It is an object of the present invention to obtain a special composite fiber which is randomly different among single fibers, and to provide a novel heat-fusible composite fiber having natural spots and soft texture similar to natural fiber.

[Brief description of drawings]

FIG. 1 is an example of a photograph showing the cross-sectional structure of the fiber of the present invention. FIG. 2 is a schematic sketch diagram of an example of a typical composite shape of the fiber of the present invention. FIG. 3 is a cross-sectional view showing an example of a spinneret device for fibers of the present invention, and FIG. 4 is a view of a distribution plate of the spinneret device as seen from the XX ′ plane. FIG. 5 is a model view of the polymer composite flow of each block when the two-component polymer composite flow reaching the distribution plate is radially distributed. FIG. 6 shows an example of a general composite fiber.

Claims (2)

[Claims] 1. A polyolefin (A polymer) and a melting point of 150.
A composite fiber made of polyester or polyamide (B polymer) that is crystalline at a temperature of ℃ or higher, and the composite shape of A polymer and B polymer is a fiber when the weight ratio of A polymer and B polymer is in the range of 15:85 to 85:15. Although they have substantially the same shape in the longitudinal direction, they are randomly different among the single fibers, and the single fibers have a composite shape in which one component forms a layered divided layer and one component has an independent island. In the state where a composite shape having a linear component is mixed with a composite structure in which two components are unevenly distributed to form a laminated structure, and the A polymer and the B polymer in the fiber cross section of the single fiber are mixed. The average value x of the contact length at the interface is the average perimeter y of the fiber cross section.
The heat-fusible conjugate fiber is represented by the relationship represented by the following formula (1) or (2). 1.0 × a / 100 ≦ x / y ≦ 10.0 × a / 100 However, when a ≦ b ……
(1) 1.0 × b / 100 ≦ x / y ≦ 10.0 × b / 100 However, when b ≦ a ……
(2) a and b represent the weight% of A polymer and B polymer, respectively. 2. A polyolefin (A polymer) and a melting point of 150.
A crystalline polyester or polyamide (B polymer) which is crystalline above ℃ is melt extruded separately, and within 5 minutes after the start of contact between these two polymers, the weight ratio of A polymer to B polymer is 15:85 to 85: In the range of 15, a layered composite form is formed through a static mixer immediately before spinning, and the layered polymer stream is redistributed and redistributed with a number of divisions smaller than the number of nozzle holes, and then spun from a porous spinning nozzle. A method for producing a heat-fusible composite fiber.