WO2022039129A1 - Composite fiber, hollow fiber and multifilament - Google Patents

Abstract

The present invention relates to a composite fiber wherein: two or more kinds of polymers, which are different from each other in the dissolution rate in a solvent, are stacked from the center of the fiber in the direction toward the fiber surface in a cross-section of the fiber; the innermost layer comprising the center of the fiber contains an easily soluble polymer; and two or more kinds of poorly soluble polymers, which have different melting points, are unevenly distributed in at least one layer other than the innermost layer.　The present invention also relates to a multifilament which contains a flat hollow fiber, wherein the coefficient of variation CV of the rotation angle of the major axis of the flat hollow fiber is from 15% to 50%.

Description

Composite fibers, hollow fibers and multifilaments

The present invention relates to composite fibers, hollow fibers and multifilaments suitable for textiles for clothing, which are excellent in wearing comfort.

Synthetic fibers made of polyester, polyamide, etc. have excellent mechanical properties and dimensional stability, so they are widely used from clothing applications to non-clothing applications. However, in recent years when people's lives have diversified and people have come to seek a better life, there is a demand for fibers having a higher tactile sensation and function.

In particular, textiles for clothing that come into contact with human skin are often required to have excellent wearing comfort, and in particular, there is a strong demand for fibers that have a texture that is directly linked to human comfort, such as that of natural fibers. This is because the texture and function of natural fibers such as hemp, wool, cotton, and silk are very well-balanced, and the complex appearance and texture of these fibers makes humans feel attractive and luxurious. Is.

As an example of the technology aiming to realize the comfortable texture realized by such natural fibers, by devising the cross section of the synthetic fiber, a void structure containing air is formed in the fabric, and an appropriate repulsion feeling and swelling are formed. Various techniques have been proposed that express a soft texture with a certain texture.

In Patent Document 1, a hollow fiber obtained by using a spinneret for hollow is subjected to false twisting to impart crimping, and at the same time, the hollow cross section is deformed and flattened to flatten a flat hollow cross section similar to cotton. Hollow fibers that impart shape and twist have been proposed. It is said that the flat hollow fiber can obtain a swelling and repulsive texture like cotton.

Further, in Patent Document 2, a core-sheath composite fiber in which an easily alkali-soluble polymer is used as a core component and a poorly alkali-soluble polymer is used as a sheath component, and a part of the core component is exposed on the fiber surface is subjected to false twisting. Then, by eluting the core component by alkaline treatment, a C-shaped hollow fiber having a continuous hollow portion and an opening in the fiber axis direction has been proposed. It is said that the core-sheath composite fiber has a C-shaped hollow effect when it is made into a woven or knitted fabric, and can give a soft texture while having a light weight feeling and an appropriate repulsive feeling.

Further, Patent Document 3 has a fiber cross section in which two or more kinds of polymers having different dissolution rates in a solvent are laminated in the cross-sectional direction to form an outermost layer, an intermediate layer, and an innermost layer, and the outermost layer and the innermost layer are formed. A bulky and lightweight multifilament in which the polymer to be formed is an easily soluble polymer and two or more types of single yarns having different cross-sectional shapes of the intermediate layer are mixed has been proposed. In the bulky and lightweight multifilament, not only the inside of the fiber but also the surface of the fiber is composed of the easily soluble polymer, so that voids can be formed inside and outside the fiber after the easily soluble polymer is eluted, and further different after elution. Since the fiber cross sections are mixed, the crushing of the interfiber voids is suppressed, and it is possible to make a fabric that has a soft texture in addition to a lightweight feeling and swelling.

Japanese Patent Application Laid-Open No. 54-151650 Japanese Patent Application Laid-Open No. 01-052839 Japanese Patent Application Laid-Open No. 2019-167646

As in Patent Document 1, if the hollow fiber is false-twisted to give a void structure inside and outside the fiber, there is a possibility that the texture like cotton, which is a natural fiber, can be reproduced to some extent. However, in Patent Document 1, the technical idea is that the fibers are tightly focused by false twisting and deformed while crushing the hollow portion, and the bulge and the texture with a feeling of repulsion that feels comfortable when worn as clothes are obtained. There was a shortage.

Further, in the method of false-twisting a core-sheath composite fiber having an easily alkali-soluble polymer as a core component and a poorly alkali-soluble polymer as a sheath component as in Patent Document 2, an alkali treatment is performed after weaving and knitting. As a result, the core component is eluted and a hollow portion can be formed. Therefore, the hollow portion is not crushed by the false twisting process, and an interfiber void can be formed due to a high hollow ratio and a crimped form. However, in order to prevent uneven elution of the core component, it has a C-shaped cross-sectional shape with a large opening, and adjacent fibers and fibers not only cause the opening to bite and the texture becomes hard, but also continue to be used. In some cases, the feeling of lightness and repulsion was reduced.

Further, both Patent Document 1 and Patent Document 2 use a false twisting process in which the multifilament is heat-set in a twisted state and then untwisted to impart crimping. For this reason, the heat treatment during higher-order processing tends to cause the crimps to settle, and there is a case where the bulge that feels comfortable when worn as clothing is insufficient. Furthermore, since the crimps of each fiber in the multifilament are uniform, the texture obtained when textiles are made monotonous, and in order to realize a complex texture like natural fibers, advanced weaving is required. It was necessary to do so, or to mix fibers with other materials including natural fibers.

On the other hand, the method of utilizing the interfiber voids formed by eluting the fiber surface as in Patent Document 3 is effective from the viewpoint of flexibility, but can be obtained by mixing different fiber cross sections. There is a limit to the effect of suppressing crushing of the interfiber voids, and it is hard to say that the interfiber voids are so coarse that a bulge is felt.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to control the void structure inside the fibers and between the fibers to provide a comfortable wearing feeling having an appropriate repulsive feeling and a soft texture with swelling. It is an object of the present invention to provide composite fibers, hollow fibers and multifilaments suitable for obtaining excellent textiles.

The object of the present invention is achieved by the following means.
(1) In the cross section of the fiber, two or more kinds of polymers having different dissolution rates in a solvent are laminated from the center of the fiber toward the surface of the fiber.
The innermost layer containing the fiber center contains an easily soluble polymer, and the innermost layer contains the easily soluble polymer.
A composite fiber in which two types of sparingly soluble polymers having different melting points are unevenly distributed in at least one layer other than the innermost layer.
(2) The composite fiber according to (1), wherein the relationship between the inscribed circle diameter RA and the circumscribed circle diameter RB of the fiber is 1.2 ≦ RB / RA ≦ 2.4 in the fiber cross section.
(3) The method according to (1) or (2), wherein in the cross section of the fiber, the easily soluble polymer communicates from the center of the fiber to the surface of the fiber, and the communication width is 10% or less of the fiber diameter. Composite fiber.
(4) The composite fiber according to any one of (1) to (3), wherein the outermost layer contains the easily soluble polymer in the cross section of the fiber.
(5) A hollow fiber from which the easily soluble polymer has been removed from the composite fiber according to any one of (1) to (4).
(6) A multifilament containing flat hollow fibers.
A multifilament having a coefficient of variation CV of 15 to 50% for the rotation angle of the long axis of the flat hollow fiber.
(7) The multifilament according to (6), wherein the flat hollow fiber has a flatness of 1.2 or more in the cross section of the fiber.
(8) The multifilament according to (6) or (7), wherein the flat hollow fiber is composed of at least two kinds of polymers having different melting points in the cross section of the fiber.
(9) The flat hollow fiber has an opening from the center of the fiber toward the surface of the fiber.
The multifilament according to any one of (6) to (8), wherein the width of the opening is 10% or less of the fiber diameter.
(10) The composite fiber according to any one of (1) to (4), the hollow fiber according to (5), or the multifilament according to any one of (6) to (9) is partially contained. Fiber products.

The composite fiber, hollow fiber and multifilament of the present invention have the above-mentioned characteristics, so that the void structure inside the fiber and between the fibers is finely controlled, and the wearer realizes an appropriate repulsive feeling and a soft texture with swelling. You can get a textile with excellent comfort.

1 (a), 1 (b), 1 (c), and 1 (d) of FIG. 1 are schematic cross-sectional structures of the composite fiber of the present invention. 2A, 2B, and 2C are schematic cross-sectional structures of the composite fiber of the present invention. 3A, 3B, 3C, and 3D are schematic cross-sectional structures of the composite fiber of the present invention. 4A and 4B are schematic cross-sectional structures of conventional composite fibers. FIG. 5 is a schematic cross-sectional structure of the multifilament of the present invention. FIG. 5A is a diagram for understanding flatness. FIG. 5B is a diagram for understanding the coefficient of variation CV of the rotation angle of the long axis in the fiber in the multifilament, and the broken line of the outer frame means the upper, lower, left and right sides of the captured image. 6 (a), 6 (b), and 6 (c) are schematic cross-sectional structures of the fibers constituting the multifilament of the present invention. FIG. 7A is a schematic diagram of the cross-sectional structure of the fibers constituting the multifilament of Example 6. FIG. 7B is a schematic cross-sectional structure of the fibers constituting the multifilament of the second embodiment. FIG. 8 is a schematic cross-sectional structure of the fibers constituting the multifilament of Comparative Example 3. FIG. 9 is a schematic cross-sectional structure of the fibers constituting the multifilament of the present invention. FIG. 10 is a schematic cross-sectional structure of an example of a composite fiber from which the multifilament of the present invention can be produced. FIG. 11 is an example of the crimped form of the fibers constituting the multifilament of the present invention. FIG. 12 is a cross-sectional view for explaining the method for producing a composite fiber of the present invention.

Hereinafter, the present invention will be described in detail together with desirable embodiments.

Analysis of the void structure of cotton, which is widely developed as a natural material with a bulging and soft texture, shows that in addition to having a hollow part inside the flat fiber, there are large and small interfiber voids. You can see that it is doing. This is because cotton has a twist for each fiber, and by bundling multiple fibers with this twist, complicated voids and irregularities are formed when making textiles. It is thought that a peculiar touch and texture are created.

As a result of diligent studies by the present inventors in order to realize the formation of such complicated voids unique to nature, the fibers are subjected to higher-order processing such as weaving and then the crimped morphology is developed in the fabric. It was discovered that the twisting of multiple fibers gathered in the above causes the development of interfiber voids of various sizes. Furthermore, by eluting the easily soluble polymer inside the fiber to form a hollow portion inside the fiber, it is possible to obtain a complicated void structure that was difficult to obtain with conventional synthetic fibers and processed yarns utilizing the same. The basis of the present invention is the realization of a soft texture with a moderate repulsion and swelling that has never been seen before.

Specifically, in the cross section of the fiber, two or more kinds of polymers having different dissolution rates with respect to the solvent are laminated from the fiber center toward the fiber surface, and the innermost layer including the fiber center contains the easily soluble polymer and is the most. It is a requirement of the present invention that two types of sparingly soluble polymers having different melting points are unevenly distributed in at least one layer other than the inner layer.

In the present invention, a polymer having a relatively high dissolution rate with respect to the solvent used for the dissolution treatment is referred to as an easily soluble polymer, and a polymer having a slow dissolution rate is referred to as a poorly soluble polymer. Further, in consideration of simplification of dissolution treatment and shortening of time in higher-order processing, it is preferable that the dissolution rate ratio (easily soluble polymer / poorly soluble polymer) is 100 or more when the poorly soluble polymer is used as a reference. , 1000 or more is more preferable. When the dissolution rate ratio is 1000 or more, the dissolution process can be completed in a short time. Therefore, in addition to increasing the process rate, a higher quality fabric can be obtained without unnecessarily deteriorating the poorly soluble polymer. Obtainable.

In the composite fiber of the present invention, in order to stably form a hollow portion inside the fiber without being influenced by the structure such as weaving, two or more kinds of polymers having different dissolution rates with respect to the solvent in the cross section of the fiber. Is laminated from the fiber center toward the fiber surface, and it is necessary that the innermost layer including the fiber center contains an easily soluble polymer. Further, the innermost layer is preferably made of an easily soluble polymer.

When the textile is made, the hollow part is stably formed inside the fiber, which not only improves the swelling and lightness of the textile, but also the presence of an air layer inside the fiber makes each fiber appropriate. It is possible to flexibly deform while having a repulsive feeling, and it is possible to obtain an appropriate repulsive feeling and a soft texture with a bulge, which is the object of the present invention.

Further, as the hollow ratio inside the fiber becomes larger, a feeling of lighter weight and flexibility can be noticeably felt. Therefore, in the composite fiber of the present invention, the area ratio occupied by the innermost layer including the fiber center is preferably 10% or more. , More preferably 20% or more. Further, while increasing the area ratio of the innermost layer is preferable from the viewpoint of lightness, the repulsive feeling may be impaired because the strength is lowered due to excessive elution of the innermost layer and the hollow portion is liable to be crushed. The practical upper limit of the area ratio is 50%.

In the composite fiber of the present invention, it is important that the fiber develops a crimped form after being subjected to higher-order processing such as weaving and knitting. When the fibers in the fabric are crimped and twisted, the adjacent fibers and the crimped morphology are entangled to develop interfiber voids of various sizes, which gives an appropriate repulsive feeling when made into a textile. Not only can it develop a soft texture with a bulge, but it can also exhibit functions such as water absorption and quick-drying due to the capillary phenomenon of fine interfiber voids and stretchability due to the coiled crimped form.

In order to develop a crimped morphology on the fiber after performing higher-order processing such as weaving, a composite cross section having a latent crimping property such that crimping is developed by heat treatment may be used, and the shrinkage difference in the cross section of the fiber. By arranging the different polymers so that their respective centers of gravity are different, the fibers are greatly curved toward the high shrinkage polymer side after the heat treatment, and these are continuous to form a three-dimensional spiral structure.

That is, in order to achieve the object of the present invention, it is important to arrange polymers having different shrinkage differences in the cross section of the fiber so as to maintain a sufficient distance between the centers of gravity. It is necessary that two kinds of sparingly soluble polymers having different melting points are unevenly distributed in at least one layer.

Here, the fact that the sparingly soluble polymers having different melting points are unevenly distributed in the present invention means that the high melting point in the left and right or upper and lower fiber cross sections is defined as the straight line that evenly divides the fiber cross section into two through the fiber center. The area ratio of the sparingly soluble polymer on the side to the sparingly soluble polymer on the low melting point side is 100: 0 to 70:30 on one fiber cross section and 30: 70 to 0: 100 on the other fiber cross section. It means that there is a straight line that is a range (for example, the straight line I in FIG. 1A).

The composite structure of the composite fiber of the present invention is not particularly limited as long as the sparingly soluble polymers having different melting points are unevenly distributed. The composite structure includes a side-by-side type as shown in FIG. 1 (a) and FIG. 1 (c), a sea-island type as shown in FIG. 1 (b), and an eccentric core sheath type as shown in FIG. 1 (d). In addition, a blend type and the like can be mentioned. Among these, from the viewpoint of widening the distance between the centers of gravity and enhancing the crimp-developing power, it is preferable that the poorly soluble polymers having different melting points are bonded to a side-by-side type in which they are completely separated.

When joined in a side-by-side type, the interface between poorly soluble polymers with different melting points is small, so the distance between the centers of gravity between the polymers in the composite cross section can be maximized, and the crimp-developing power can be maximized. Further, since the crimped form has a fine spiral structure, it is possible to impart excellent stretchability, and it is preferable because a stress-free wearing comfort can be obtained with an appropriately stretchable fabric.

In the fiber cross section of the composite fiber of the present invention, it is preferable that the relationship between the inscribed circle diameter RA and the circumscribed circle diameter RB of the fiber is 1.2 ≦ RB / RA ≦ 2.4.

Here, the inscribed circle diameter RA and the circumscribed circle diameter RB in the present invention mean that the fiber is embedded with an embedding agent such as epoxy resin, and the cross section of the fiber in the direction perpendicular to the fiber axis is scanned by a scanning electron microscope (SEM). ), The image is taken and obtained at a magnification at which fibers of 10 filaments or more can be observed.

By analyzing fibers randomly extracted from each captured image in the same image using image analysis software, the inside of the fiber surface and at least two points (for example, a1 and a2 in FIG. 2A). Calculated for the diameter of a circle that is in contact and has the maximum diameter that exists only inside the fiber and has the maximum diameter that can be taken in the range where the circumference of the inscribed circle and the fiber surface do not intersect (for example, A in FIG. 2A). The simple number average of the results of this for 10 filaments is obtained, and the value rounded off to the nearest circle is defined as the inscribed circle diameter RA.

Further, the minimum possible range is that the circumscribed circle is circumscribed with the fiber surface at at least two points (for example, b1 and b2 in FIG. 2A) and exists only outside the fiber so that the circumference of the circumscribed circle and the fiber surface do not intersect. Calculate the diameter of a circle having a diameter of (for example, B in (a) of FIG. 2), calculate a simple number average of the results of doing this for 10 filaments, and round off the value after the decimal point to the circumscribed circle diameter RB. do.

Further, RB / RA is calculated by dividing the RB obtained for each fiber by RA above, obtains a simple numerical average of the results obtained by performing this for 10 filaments, and rounds off to the second decimal place. Let it be RB / RA.

The cross-sectional shape of the composite fiber of the present invention is not limited, but the fibers are crimped and twisted after being subjected to higher-order processing such as weaving and knitting, so that the fibers are crimped and crimped with adjacent fibers. It is important that the morphology is intertwined to develop interfiber voids of various sizes. From this point of view, if the cross section of the fiber is a deformed cross section, the interfiber voids created when the fiber is twisted can be more complicated and increased, so that the ratio of the inscribed circle diameter RA to the circumscribed circle diameter RB of the fiber. It is preferable that the RB / RA (degree of deformation) is 1.2 or more.

Further, when the RB / RA is 1.5 or more, the interfiber gaps can be stably formed without aligning the crimping phases between the adjacent fibers, and the fabric can be made uniform without spots such as streaks. Since it can be used as an appearance, it can be mentioned as a more preferable range from the viewpoint of quality control. Further, the larger the RB / RA is, the more preferable it is from the viewpoint of stably forming the interfiber voids. On the other hand, the light reflected on the fiber surface not only causes glare in some cases but also has an edged cross-sectional shape. Since the flexibility may be impaired due to the bending rigidity becoming higher than necessary, the practical upper limit of RB / RA is 2.4.

When the cross-sectional shape of the composite fiber of the present invention is a deformed cross-section, any deformed cross-section such as a flat shape, a multi-leaf shape, a polygonal shape, a gear shape, a petal shape, a star shape, etc. can be adopted, but an appropriate repulsion can be adopted. From the viewpoint of further enhancing the feeling and flexibility, it is preferable that the fiber shape is a flat shape as shown in FIG. 2 (a) or a multi-leaf shape as shown in FIG. 2 (b). If the flat shape is as shown in FIG. 2A, when the flat cross section is bent along the plane perpendicular to the long axis, the repulsive feeling due to the high bending rigidity is bent along the plane perpendicular to the short axis. In this case, the flexibility due to the low bending rigidity can be obtained, so that a texture having an appropriate repulsive feeling and softness can be obtained.

Further, in the case of using a multifilament, when the fibers are twisted by expressing a crimped form, the interfiber voids due to steric hindrance increase, and not only can the appropriate repulsion feeling and swelling be further enhanced, but also. By partially aligning the long axis directions of the cross sections of the flat fibers, there will be differences in voids and irregularities between adjacent fibers where the long axis directions of the cross sections are aligned and where they are not aligned. Complex voids and irregularities can be formed between the fibers. From the viewpoint of being able to express a peculiar tactile sensation unique to nature, it is also preferable that the shape is flat.

On the other hand, in the case of the multi-leaf shape as shown in FIG. 2B, by imparting irregularities on the fiber surface, it is possible to suppress glare due to diffused reflection of light and improve water absorption and quick-drying due to fine interfiber voids. From the viewpoint, it is preferable. However, if the number of uneven portions becomes too large, the intervals between the uneven portions become finer and the effect gradually decreases. Therefore, the practical upper limit of the convex portions of the multi-leaf shape in the present invention is 20. It is an individual.

Further, if the flat and multi-leaf shape as shown in FIG. 2 (c) is used, the above-mentioned flat and multi-leaf shape can be combined. Therefore, from the viewpoint that the textile, which is the object of the present invention, has an appropriate repulsive feeling and a soft texture with swelling, and also has functions such as water absorption and quick drying, it is particularly flat and multi-leaf-shaped. preferable.

In the fiber cross section of the composite fiber of the present invention, it is preferable to have a communicating portion in which the easily soluble polymer communicates from the center of the fiber to the surface of the fiber.

In the composite fiber of the present invention, it is necessary to elute the easily soluble polymer in the innermost layer in order to stably form a hollow portion inside the fiber. Since the solution of the easily soluble polymer with a solvent is removed from the fiber surface, if a communication portion from the fiber surface to the innermost layer can be provided, the time required for dissolving the easily soluble polymer can be significantly shortened. Not only that, it is also possible to impart water absorption and water retention due to the capillary phenomenon at the opening formed after elution of the easily soluble polymer. From this point of view, it is preferable that the easily soluble polymer communicates from the center of the fiber to the surface of the fiber.

The communication width of the easily soluble polymer is preferably 10% or less of the fiber diameter.
Here, the fiber diameter in the present invention means a fiber having 10 or more filaments in which a composite fiber is embedded with an embedding agent such as an epoxy resin and the cross section of the fiber in the direction perpendicular to the fiber axis is scanned by a scanning electron microscope (SEM). The image is taken and obtained as the observable magnification. The diameter of the fibers randomly extracted from each image taken in the same image was measured in μm units up to the first decimal place, and this was performed for 10 filaments to obtain a simple numerical average, which was the first decimal place. The value rounded to the nearest whole number is taken as the fiber diameter (μm). Here, when the cross section of the fiber in the direction perpendicular to the fiber axis is not a perfect circle, the area is measured and the value of the diameter obtained in terms of a perfect circle is adopted.

Further, in order to obtain the communication width in the present invention, first, the composite fiber of the present invention is embedded with an embedding agent such as an epoxy resin, and the cross section of the fiber in the direction perpendicular to the fiber axis is subjected to a transmission electron microscope (TEM). The image is taken at a magnification at which 10 or more fibers can be observed. Then, in the composite fiber of the obtained image, when the easily soluble polymer communicates from the fiber center to the fiber surface, the communication portion is communicated through the fiber center G by analyzing with image analysis software. The shortest width of the width W of the communication portion in the direction perpendicular to the parallel straight line S (for example, S in FIG. 3C) (for example, W in FIG. 3C) is calculated in μm units. .. The simple number average of the result of doing this for 10 filaments is obtained, and the value rounded to the second decimal place is used as the communication width.

Further, a value obtained by dividing the division width obtained for each filament by the fiber diameter and multiplying by 100 is calculated, a simple numerical average of the results obtained by performing this for 10 filaments is obtained, and the value rounded to the nearest whole number is used for the fiber diameter. The ratio of communication width (%).

If the communication width of the easily soluble polymer is 10% or less of the fiber diameter, the opening formed after removing the easily soluble polymer is excessively wide, and the fibers are entangled with each other or the opening is displaced. It is possible to prevent the part from being crushed, and it is possible to prevent the appropriate repulsive feeling and the soft texture with swelling from being impaired.

Furthermore, if the communication width is 5% or less of the fiber diameter, not only can the fibrilization due to fiber wear due to the openings formed after elution of the easily soluble polymer be suppressed, but also post-processing such as applying a functional agent is applied. This is a more preferable range because it can prevent the functional agent that has entered the hollow portion from falling off due to washing or the like and can greatly improve the performance durability of the functional agent. However, if the communication width is too narrow, it becomes difficult to dissolve the easily soluble polymer. Therefore, the practical lower limit of the communication width is 1% of the fiber diameter.

In the fiber cross section of the composite fiber of the present invention, it is preferable that the outermost layer contains an easily soluble polymer, and it is more preferable that the outermost layer is made of an easily soluble polymer. However, the outermost layer in the present invention means a layer containing 80% or more of the fiber surface.

If the outermost layer is an easily soluble polymer, the interfiber voids naturally expand when the easily soluble polymer is removed, and the fibers fixed at the binding point of the woven or knitted fabric can move, resulting in flexibility and appearance with a high void ratio. It is possible to obtain the effect of improving the feeling of lightness by reducing the density.

From this point of view, it is preferable that the area ratio of the outermost layer in the fiber cross section of the composite fiber is high, and if the area ratio is 10% or more, the effect of improving flexibility and lightness is not affected by the fabric structure. Is mentioned as a preferable range because it can sufficiently obtain. However, if the area ratio is too high, it may cause a decrease in the repulsive feeling due to a decrease in the bending rigidity, so that the practical upper limit is 30%.

With the composite fiber of the present invention, a hollow fiber composed of only a poorly soluble polymer is formed by first performing high-order processing such as weaving and then heat-treating to develop a crimped morphology, and then removing the easily soluble polymer in the innermost layer. , And a multifilament made of the hollow fiber can be obtained. Due to its unique fiber cross-sectional shape and interfiber voids, the multifilament has a soft texture with an appropriate repulsion and swelling, and also has functions such as water absorption and quick drying and stretchability. It is possible to obtain excellent textiles.

Furthermore, as a multifilament, in order to maximize the unique tactile sensation and texture due to the formation of complex voids and irregularities unique to nature, as a result of diligent studies by the present inventors, the twist of flat fibers is controlled and the length of the cross section is controlled. It was discovered that by appropriately aligning the axial directions, complicated voids and irregularities that were difficult to obtain with conventional synthetic fibers and processed yarns using them can be formed.

That is, in a multifilament made of flat fibers having no twist, the voids obtained by aligning all the long axis directions of the cross sections of the fibers are small, and the unevenness is also flat. On the other hand, in the case of a multifilament made of flat fibers twisted by false twisting, the twist of each fiber is uniform and the long axis direction of the cross section faces different directions at the time of untwisting. And unevenness can be obtained, but it may be monotonous.

On the other hand, if the twist is controlled so that the long axis directions of the cross sections of the flat fibers in the multifilament are partially aligned, the long axis directions of the cross sections are aligned between the adjacent fibers when the textile is used. Differences in voids and irregularities are created in places that are not aligned with the fibers, and complex voids and irregularities can be formed between the fibers. As a result, in addition to being able to express a unique tactile sensation unique to nature, by providing a hollow portion inside the fibers, a soft texture with an appropriate repulsion and swelling is also expressed in combination with complicated voids and irregularities between the fibers. You can.

The present invention is constructed by designing fibers based on this idea. Specifically, the multifilament of the present invention contains flat hollow fibers. The multifilament of the present invention is preferably composed of flat hollow fibers, and it is a requirement of the present invention that the coefficient of variation CV of the rotation angle of the long axis in the flat hollow fibers in the multifilament is 15 to 50%.

In the present invention, it is important that the fibers constituting the textile are flat hollow fibers.

If the fiber cross section is a flat cross section as shown in FIG. 5A, the repulsive feeling due to the high flexural rigidity is felt on the plane perpendicular to the short axis when bent along the plane perpendicular to the long axis of the flat cross section. When bent along the line, flexibility due to low bending rigidity can be obtained, so that a texture having an appropriate repulsive feeling and softness can be obtained.

In order to exhibit the above effect, the flatness is preferably 1.2 or more, and more preferably 1.5 or more. Within this range, interfiber voids are formed due to steric hindrance when the flat hollow fibers are twisted, and swelling when made into a textile can also be obtained.

Further, the higher the flatness is, the more preferable it is from the viewpoint of stably forming the interfiber voids, but in some cases, the light reflected on the fiber surface not only causes uneven appearance (glare) but also has edges. Since the flexibility may be impaired due to the bending rigidity becoming higher than necessary depending on the cross-sectional shape, the upper limit of the flatness in the present invention is 2.4.

Here, the flatness referred to in the present invention means that the multifilament is embedded with an embedding agent such as an epoxy resin, and the cross section of the fiber in the direction perpendicular to the fiber axis is 10 or more with a scanning electron microscope (SEM). An image is taken and obtained as a magnification at which the fibers can be observed. By analyzing the fibers randomly extracted from each photographed image in the same image using image analysis software, the distance is the longest among arbitrary points on the outer circumference of the fibers as shown in FIG. 5 (a). The long axis is the straight line (c1-c2) connecting two distant points (c1, c2), and the straight line (d1-d2) perpendicular to the long axis through the midpoint of the long axis is the short axis. Calculate the value obtained by dividing the length by the length of the minor axis. The result of doing this for 10 fibers is obtained as a simple number average, and the value rounded to the second decimal place is defined as the flatness.

Further, by having a hollow portion inside the fiber, not only the swelling and lightness of the textile are improved, but also each fiber can be flexibly deformed while having an appropriate repulsive feeling, and the above-mentioned flat cross section can be obtained. The effect of can be made more prominent.

Further, when the hollow ratio inside the fiber is increased, a feeling of swelling and light weight can be more noticeably felt. Therefore, in the flat hollow fiber in the multifilament of the present invention, the area ratio occupied by the hollow portion including the fiber center is 10. % Or more is preferable. Further, in order to improve the porosity of the fiber bundle and emphasize the lightness, and to emphasize the flexibility of the fabric, it is more preferable that the area ratio of the hollow portion is 20% or more. Can be given as. In the case of the above-mentioned range, in the case of the above-mentioned flat cross section, the deformation of the single fiber is directional, and the twisted morphology characteristic of the present invention causes the fiber bundle to be complicatedly deformed. It has a very comfortable feel that cannot be experienced with thread processing.

It is preferable from the viewpoint that the lighter weight of the fiber bundle and textile becomes more remarkable as the area ratio of the hollow portion is increased. However, when the thickness of the polymer constituting the fiber becomes thin, the strength is likely to decrease and the hollow portion is liable to be crushed, and there is a possibility that the comfortable repulsion feeling which is the object of the present invention may not be exhibited well. The practical upper limit of the area ratio of the hollow portion in the present invention is 50%.

Here, the hollow ratio referred to in the present invention means that the multifilament is embedded with an embedding agent such as an epoxy resin, and the cross section of the fiber in the direction perpendicular to the fiber axis is 10 or more with a scanning electron microscope (SEM). An image is taken and obtained as a magnification at which the fibers can be observed. If the fibers randomly extracted from each captured image in the same image have a hollow portion such as H in FIG. 5A, the fibers can be analyzed using image analysis software. The area obtained from the outer shape including the hollow portion of the fiber and the area of the hollow portion are obtained, respectively, and the area of the hollow portion is divided by the area obtained from the outer shape including the hollow portion of the fiber, and the value is calculated by multiplying by 100. A simple number average of the results of this for 10 fibers is obtained, and the value rounded to the first decimal place is defined as the hollow ratio (%).

The fiber cross-sectional shape is flat as shown in FIG. 5A, and has a cross-sectional shape (multileaf shape, polygonal shape, gear shape, petal shape, star shape, etc.) having a convex portion on the fiber surface. ) Is preferable. This is because it is possible to suppress appearance unevenness (glare) due to diffused reflection of light and to enhance water absorption due to fine interfiber voids. However, if the number of convex portions becomes too large, the effect gradually decreases, so that the practical upper limit of the convex portions is 20.

In the present invention, if the twist is controlled so that the long axis directions of the cross sections of the flat fibers in the multifilament are partially aligned, the long axis directions of the cross sections are aligned between the adjacent fibers when the textile is made. There will be differences in voids and irregularities where they are not aligned. The coefficient of variation CV of the rotation angle of the long axis of the flat hollow fibers in the multifilament is 15 to 50% as a requirement for forming complicated voids and irregularities on the textile surface, which are characteristic of the present invention. Is important.

The fluctuation coefficient of the rotation angle of the long axis referred to in the present invention is a scanning electron microscope (SEM) for a cloth cross section made of a multifilament, which is perpendicular to the length direction of the cloth and perpendicular to the fiber axis direction of the multifilament. An image is taken and obtained at a magnification at which 20 or more fibers can be observed. In the obtained fiber of the image, when the fiber had a flat cross section, the outer circumference of the fiber was farthest away as shown in FIG. 5 (b) by analyzing with image analysis software. The long axis is the straight line (c1-c2) connecting the two points (c1, c2), and the straight line that passes through the middle point of the long axis of the flat hollow fiber and is parallel to the lower side of the photographed image is the middle point of the long axis. Rotate it counterclockwise to the center and evaluate the rotation angle (θ) when the major axis and the slope of the straight line match.

This evaluation was performed on 20 fibers randomly selected from the multifilaments of the same image ((1) to (20) in (b) of FIG. 5), and the standard deviation and the average value were obtained and standardized. The deviation is divided by the average value and multiplied by 100, and the value rounded to the first digit is used as the coefficient of variation CV (%) of the rotation angle of the long axis.

In the present invention, the coefficient of variation CV of the rotation angle of the long axis in the flat hollow fiber in the multifilament needs to be 15% or more, and by setting it within this range, the long axis direction of the cross section becomes uneven. Due to the unevenness on the surface of the developed textile, when the surface of the fabric is touched, a smooth tactile sensation due to a large friction fluctuation is developed. Further, complicated voids are created between the fibers, and in combination with the hollow portion inside the fibers, an appropriate repulsive feeling and a soft texture with swelling are also developed.

The coefficient of variation CV of the rotation angle of the long axis referred to in the present invention is more preferably 25 to 40%. As a result, the apparent density decreases when the fabric is made into a cloth, and the effect of improving swelling is also added. On the other hand, if the coefficient of variation CV becomes too large, the unevenness becomes too fine and the frictional fluctuation becomes small, which approaches a monotonous tactile sensation. Therefore, 50% of the coefficient of variation CV is a substantial upper limit.

In order to control the coefficient of variation of the rotation angle of the long axis in the flat hollow fibers in the multifilament, flat hollow fibers with different twists are separately produced by false twisting, and then mixed and bundled by entanglement or the like. Can be considered. Further, if it is possible to develop a crimped form in the flat hollow fiber after performing higher-order processing such as weaving using a flat hollow fiber having a latent crimping property that causes crimping by heat treatment, it is possible to roll the fiber. Since the crimp phase difference between the fibers is locally generated at the time of contraction development, the coefficient of variation CV of the rotation angle of the long axis in the flat hollow fibers in the multifilament can be easily set in the target range.

From this point of view, in the flat hollow fiber in the multifilament of the present invention, in order to obtain a fiber having latent crimping property such that the fiber is crimped by heat treatment, at least two kinds of polymers having different melting points in the cross section of the fiber are used. It is preferably composed of. If the fibers are composed of polymers having different melting points, the fibers are greatly curved toward the high-shrink polymer side after the heat treatment due to the shrinkage difference caused by the difference in melting point, and these are continuous to form a three-dimensional spiral structure.

In order to increase the crimp-developing power, it is preferable to have a composite cross section in which polymers having different melting points maintain a sufficient distance between the centers of gravity. From this viewpoint, the polymers having different melting points are shown in FIG. 6 (a). It is more preferable to join in such a side-by-side type. That is, since the interface between polymers having different melting points is small, the distance between the centers of gravity between the polymers in the composite cross section can be maximized, and the crimp-developing force can be maximized.

Furthermore, the crimped form has a fine spiral structure, which makes it possible to impart excellent stretchability, and a stress-free wearing comfort can be obtained with an appropriately stretchable fabric.

Further, the flat hollow fibers in the multifilament have a cross-sectional shape in which the direction (angle) of the bonding surface of the polymer having a different melting point for each single fiber is random (the four types in FIG. 9 are examples of the cross-sectional shape). Is particularly preferable, and the crimping morphology developed by the heat treatment differs for each single fiber due to the difference in the distance between the centers of gravity, so that the crimping phase difference between the fibers can also be increased. Due to this effect, the coefficient of variation (CV) of the rotation angle of the long axis in the flat hollow fiber in the multifilament can be brought closer to the optimum range.

In the multifilament of the present invention, the coefficient of variation of the rotation angle of the long axis of the flat hollow fiber in the multifilament is set as the target range, and the hollow portion of the flat hollow fiber is stabilized without being influenced by the structure such as weaving or knitting. It is preferable to use the following composite fibers in order to form the fibers. That is, in the cross section of the fiber, two or more kinds of polymers having different dissolution rates with respect to the solvent are laminated from the fiber center toward the fiber surface, and the innermost layer including the fiber center is made of an easily soluble polymer, and at least other than the innermost layer. It is preferable to use a composite fiber in which one layer is composed of two types of sparingly soluble polymers having different melting points.

If the composite fiber is subjected to higher-order processing such as weaving and then a crimped form is developed by heat treatment, and then the easily soluble polymer in the innermost layer is removed, the hollow portion is not crushed during the higher-order processing and is stable. A multifilament made of the formed flat hollow fibers can be obtained, and the coefficient of variation of the rotation angle of the long axis in the flat hollow fibers in the multifilament can be set in the target range by the expression of crimping.

When the flat hollow fiber in the multifilament of the present invention develops a crimped morphology by heat treatment, it is preferable to have a crimped morphology having a number of crimped ridges of 5 ridges / cm or more.

Here, the number of crimped peaks referred to in the present invention can be obtained by the following method. That is, in a cloth made of a multifilament, the multifilament is extracted from the cloth so as not to be plastically deformed, and one end of the multifilament is fixed. A load of 1 mg / dtex is applied to the other end, and after 30 seconds or more, marking is applied to any part where the distance between the two points is 1 cm in the fiber axis direction of the multifilament.

After that, the fibers are separated from the multifilament so as not to be plastically deformed, adjusted so that the space between the markings attached in advance is the original 1 cm, and fixed on the slide glass. An image of this sample is taken with a digital microscope at a magnification at which a 1 cm marking can be observed. When the multifilament has a crimped form in which the fibers are twisted as shown in FIG. 11 in the captured image, the number of crimped ridges existing between the markings is obtained. A simple number average is obtained as a result of performing this operation on 10 fibers composed of the same polymer, and the value rounded to the first decimal place is defined as the number of crimped peaks (mountain / cm).

When the number of crimped ridges is 5 ridges / cm or more, the crimped phase difference between the fibers is locally generated at the time of the occurrence of crimped fibers, so that the flat hollow fibers in the multifilament have. The coefficient of variation CV of the rotation angle of the long axis can be set as the target range.

Further, when the number of crimped ridges is 10 ridges / cm or more, not only the effect of improving the swelling can be obtained by increasing the interfiber voids due to the excluded volume effect between the fibers, but also the crimped morphology is a fine spiral structure. Since it is possible to impart stretchability by becoming, it can be mentioned as a more preferable range.

From the viewpoint of imparting stretchability, it is preferable to increase the number of crimped ridges, but when the number of crimped ridges becomes excessive, the coefficient of variation CV of the rotation angle of the long axis in the flat hollow fiber in the multifilament also increases. It becomes large and may have a monotonous tactile sensation depending on the structure such as woven and knitted fabrics. Therefore, the practical upper limit of the number of crimped ridges in the present invention for the purpose of developing a suitable tactile sensation is 50 ridges / cm.

The flat hollow fiber in the multifilament of the present invention preferably has an opening from the center of the fiber toward the surface of the fiber. If it has an opening that communicates with the hollow portion, not only water absorption due to the capillary phenomenon at the opening appears, but also the surface area of the fiber increases, so that when post-processing such as applying a functional agent is performed. The effective area of the functional agent is also increased, and the performance of the functional agent can be improved.

The width of the opening is preferably 10% or less of the fiber diameter. Here, the fiber diameter in the present invention means a fiber having 10 or more filaments in which a multifilament is embedded with an embedding agent such as an epoxy resin and the cross section of the fiber in the direction perpendicular to the fiber axis is scanned by a scanning electron microscope (SEM). The image is taken and obtained as the observable magnification. The area of fibers randomly extracted from each image taken in the same image was measured, the diameter obtained in terms of perfect circle was measured in μm units to the first decimal place, and this was performed for 10 filaments. A simple number average is obtained, and the value rounded to the first decimal place is defined as the fiber diameter (μm). Here, when a hollow portion is present in the cross section of the fiber in the direction perpendicular to the fiber axis, the area of the hollow portion is added to the area of the fiber.

Further, the width of the opening in the present invention can be obtained by the following method. That is, the multifilament is embedded with an embedding agent such as epoxy resin, and an image is taken at a magnification at which 10 or more fibers can be observed with a transmission electron microscope (TEM) in the cross section of the fiber in the direction perpendicular to the fiber axis. .. When the fiber of the obtained image has an opening from the fiber center to the fiber surface, the straight line S passing through the fiber center G and being parallel to the opening is analyzed by using image analysis software. '(For example, the width W'of the opening in the direction perpendicular to (for example, S'of (b) in FIG. 6), the shortest width is calculated in μm units. A simple number average of the results of this for 10 filaments is obtained, and the value rounded to the second decimal place is taken as the width of the opening. Further, a value obtained by dividing the width of the opening obtained for each filament by the fiber diameter and multiplying by 100 is calculated, a simple numerical average of the results obtained by performing this for 10 filaments is obtained, and the value rounded to the nearest whole number is the present invention. It is the ratio (%) of the width of the opening to the fiber diameter.

In the present invention, the width of this opening is preferably 10% or less of the fiber diameter. That is, in such a range, it is possible to prevent the fibers from getting caught between the fibers due to the opening being too wide and the hollow portion being crushed due to the displacement of the opening, and the texture such as light weight and appropriate repulsion is impaired. Can be prevented.

Further, it is more preferable that the width of the opening is 5% or less of the fiber diameter, which not only can suppress fibrillation due to fiber wear due to the opening, but also when post-processing such as applying a functional agent is performed. , It is possible to prevent the functional agent contained in the hollow portion from falling off due to washing or the like, and to greatly improve the performance durability of the functional agent. However, if the width of the opening is made too narrow, the water absorption due to the capillary phenomenon at the opening may be weakened, or the functional agent may not sufficiently enter the hollow portion when the functional agent is applied. The substantially lower limit of the width of the opening in the invention is 1% of the fiber diameter.

As the polymer constituting the composite fiber, hollow fiber and flat hollow fiber in the multifilament of the present invention, a thermoplastic polymer is preferable because it is excellent in processability. As the polymer group constituting the fiber, for example, a polymer group such as polyester-based, polyethylene-based, polypropylene-based, polystyrene-based, polyamide-based, polycarbonate-based, polymethyl methacrylate-based, polyphenylene sulfide-based, and copolymers thereof are preferable.

The thermoplastic polymers used for the composite fiber, the hollow fiber and the flat hollow fiber in the multifilament of the present invention are all the same from the viewpoint that particularly high interfacial affinity can be imparted and a fiber having no abnormality in the composite cross section can be obtained. It is preferably a polymer group and a copolymer thereof.

In addition, the polymer contains various additives such as titanium oxide, silica, inorganic substances such as barium oxide, carbon black, colorants such as dyes and pigments, flame retardants, fluorescent whitening agents, antioxidants, and ultraviolet absorbers. You may be. In particular, it is preferable that the poorly soluble polymer contains 1.0% by mass or more of titanium oxide. Then, when the easily soluble polymer is dissolved, the titanium oxide deposited on the surface of the poorly soluble polymer also falls off, resulting in unevenness on the surface, and diffuse reflection of light causes reflection by the incident angle of light. Not only the appearance is improved such that the increase / decrease (glare) can be suppressed, but also the functionality such as see-through prevention and ultraviolet shielding can be obtained by the titanium oxide inside the fiber.

As the easily soluble polymer, for example, polyester and its copolymer, polylactic acid, polyamide, polystyrene and its copolymer, polyethylene, polyvinyl alcohol and the like can be melt-molded and exhibit more easily elution than other components. It is preferable to choose from polymers.

Further, from the viewpoint of simplifying the elution step of the easily soluble polymer, the easily soluble polymer is preferably a copolymerized polyester, polylactic acid, polyvinyl alcohol or the like which exhibits easy elution in an aqueous solvent or hot water. In particular, since it exhibits easy elution to aqueous solvents such as alkaline aqueous solutions while maintaining crystallinity, fusion between composite fibers does not occur even in false twisting processing in which abrasion is applied under heating. From the viewpoint of high-order processing passability, in addition to polyester in which 5 mol% to 15 mol% of 5-sodium sulfoisophthalic acid is copolymerized and the above-mentioned 5-sodium sulfoisophthalic acid, polyethylene glycol having a weight average molecular weight of 500 to 3000 is added. Polyester copolymerized in the range of 5% by mass to 15% by mass is preferable.

The poorly soluble polymer having a different melting point in the present invention is a group of melt-moldable thermoplastic polymers such as polyester-based, polyethylene-based, polypropylene-based, polystyrene-based, polyamide-based, polycarbonate-based, polymethylmethacrylate-based, and polyphenylene sulfide-based. A combination of polymers having different melting points of 10 ° C. or more from among the polymers thereof.

The purpose of the composite fiber, hollow fiber and flat hollow fiber in the multifilament of the present invention is to develop a crimped morphology due to the difference in shrinkage of the sparingly soluble polymers having different melting points. Therefore, as a combination of poorly soluble polymers having different melting points, it is preferable to use one kind as a high shrinkage low melting point polymer and the other kind as a low shrinkage high melting point polymer. In particular, from the viewpoint of suppressing peeling and imparting stability in higher-order processing and durability for use to the fabric, the polymer combination exists in the main chain such as an ester-bonded polyester type and an amide-bonded polyamide type. It is more preferable to select from the same group of polymers having the same bond.

Examples of the combination of the low melting point polymer and the high melting point polymer in the same polymer group include copolymerized polyethylene terephthalate / polyethylene terephthalate, polybutylene terephthalate / polyethylene terephthalate, polytrimethylene terephthalate / polyethylene terephthalate, and thermoplastic polyurethane as polyesters. / Polyethylene terephthalate, Polyethylene terephthalate, Polyethylene terephthalate, Polyethylene elastomer / Polybutylene terephthalate, Nylon 66 / Nylon 610 as polyamide, Nylon 6-Nylon 66 copolymer / Nylon 6 or 610, PEG copolymerized nylon 6 / Nylon 6 Alternatively, various combinations such as 610, thermoplastic polyurethane / nylon 6 or 610, ethylene-propylene rubber finely dispersed polypropylene / polypropylene, propylene-α-olefin copolymer / polypropylene and the like can be mentioned as the polyolefin type.

Among these, the poorly soluble polymer having a different melting point should be a polyester-based combination from the viewpoint of suppressing the crushing of the hollow portion inside the fiber due to its high flexural rigidity and obtaining good color development when dyed. Is preferable.

Examples of the copolymerization component in the copolymerized polyethylene terephthalate include succinic acid, adipic acid, azelaic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, maleic acid, phthalic acid, isophthalic acid, and 5-sodium sulfoisophthalic acid. However, from the viewpoint of maximizing the shrinkage difference with polyethylene terephthalate, it is preferable to use polyethylene terephthalate in which 5 to 15 mol% of isophthalic acid is copolymerized.

Further, while attention is focused on environmental problems, it is preferable to use a plant-derived biopolymer or a recycled polymer in the present invention from the viewpoint of reducing the environmental load, and the polymer used in the above-mentioned invention is a chemical. Recycled polymers that have been recycled by any of the recycling, material recycling and thermal recycling methods can be used.

Even when a biopolymer or a recycled polymer is used, the polyester resin can make the characteristics of the present invention remarkable as its polymer characteristics, and as described above, it suppresses the crushing of the hollow portion inside the fiber due to its high bending rigidity. Moreover, good color development can be obtained when dyed. From these viewpoints, recycled polyester can be suitably used for the present invention.

The low melting point / high melting point is 70/30 as the area ratio of the poorly soluble polymer on the low melting point side and the poorly soluble polymer which is the high melting point polymer in the composite fiber, the hollow fiber and the flat hollow fiber in the multifilament of the present invention. It is preferably in the range of ~ 30/70. Within such a range, the crimped morphology due to the difference in shrinkage can be sufficiently expressed without being affected by the texture hardening due to the basis weight clogging when the low melting point polymer is highly shrunk by heat treatment, and a coarser interfiber void is obtained. be able to.

The composite fiber, hollow fiber and flat hollow fiber in the multifilament of the present invention preferably have a fiber diameter of 20 μm or less from the viewpoint of making the texture more flexible. Within this range, not only flexibility but also a feeling of repulsion can be sufficiently obtained, which is a suitable range for clothing applications such as pants and shirts, which require a firm texture.

Further, it is more preferable that the fiber diameter is 15 μm or less, so that the fiber bundle or the cloth made of the fiber bundle becomes more flexible and is suitably used for clothing applications such as inners and blouses that come into contact with the skin. However, if the fiber diameter is less than 8 μm, there may be a portion where the bending recovery property is deteriorated because the fiber diameter is too small, or the color development property may be also deteriorated. Therefore, it is preferable that the fiber diameter of the fiber in the present invention is 8 μm or more.

Further, in the textile product of the present invention in which the composite fiber, the hollow fiber and the multifilament of the present invention are contained in at least one part, the long axis direction of the cross section is aligned between the adjacent fibers when the fiber product is made. Differences are created in the voids and irregularities in the places where they are not aligned, and complicated voids and irregularities can be formed between the fibers, and a unique smooth tactile sensation can be expressed. Furthermore, by providing a hollow portion inside the fiber, it is possible to obtain a textile having excellent wearing comfort that realizes an appropriate repulsive feeling and a soft texture with a bulge in combination with complicated voids and irregularities between the fibers.

Therefore, the composite fiber, hollow fiber and multifilament of the present invention can be used for general clothing such as jackets, skirts, pants and underwear, as well as sports clothing and clothing materials, as well as interior products such as carpets and sofas by taking advantage of their comfort. , Car seats and other vehicle interiors, cosmetics, cosmetic masks, health products and other daily uses, etc., can be suitably used for a wide range of textile products.

An example of the method for producing a composite fiber, a hollow fiber and a multifilament of the present invention will be described in detail below.

As a method for producing composite fibers, hollow fibers and multifilaments of the present invention, it is suitable for a melt spinning method for producing long fibers, a solution spinning method such as wet and dry wet, and a sheet-shaped fiber structure. Examples thereof include a melt blow method and a spun bond method, but the melt spinning method is preferable from the viewpoint of increasing productivity.

Further, in the melt spinning method, it can be manufactured by using a composite base described later, and the spinning temperature at that time is the temperature at which the high melting point or high viscosity polymer mainly exhibits fluidity among the polymer types used. It is preferable to do so. The temperature indicating this fluidity varies depending on the molecular weight, but stable production can be achieved by setting the temperature between the melting point of the polymer and the melting point of + 60 ° C.

The spinning speed should be about 500 to 6000 m / min, and can be changed depending on the physical characteristics of the polymer and the purpose of use of the fiber. In particular, from the viewpoint of high orientation and improvement of mechanical properties, it is preferable to set the fiber at 500 to 4000 m / min and then stretch the fiber because the uniaxial orientation of the fiber can be promoted. At the time of stretching, it is preferable to appropriately set the preheating temperature by using a temperature at which softening is possible, such as the glass transition temperature of the polymer, as a guide. The upper limit of the preheating temperature is preferably a temperature at which the yarn path disorder does not occur due to the spontaneous elongation of the fibers in the preheating process. For example, in the case of PET (polyethylene terephthalate) in which the glass transition temperature exists in the vicinity of 70 ° C., this preheating temperature is usually set to about 80 to 95 ° C.

Further, when the discharge amount per single hole of the composite fiber, hollow fiber and multifilament of the present invention is about 0.1 to 10 g / min / hole, stable production becomes possible. The discharged polymer stream is cooled and solidified, then oiled, and is taken up by a roller having a specified peripheral speed. It is then stretched with a heating roller to give the desired composite fibers, hollow fibers and multifilaments.

Further, in the composite fiber of the present invention composed of two or more kinds of polymers, the melt viscosity ratio of the polymer used is less than 5.0 and the difference in solubility parameter value is less than 2.0, so that the composite polymer flow is stable. Is preferable because fibers having a good composite cross section can be obtained.

As the composite base used when producing the composite fiber of the present invention composed of two or more kinds of polymers, for example, the composite base described in Japanese Patent Application Laid-Open No. 2011-208313 is preferably used.

The composite base shown in FIG. 12 of the present invention is incorporated into a spinning pack in a state in which three types of members, a measuring plate 1, a distribution plate 2, and a discharge plate 3 are laminated from above, and is used for spinning. Incidentally, FIG. 12 is an example using three types of polymers such as A polymer, B polymer, and C polymer. With conventional composite caps, it is difficult to composite three or more types of polymers, and it is preferable to use a composite cap using a fine flow path as illustrated in FIG.

In the base member illustrated in FIG. 12, the amount of polymer per discharge hole and the amount of polymer per distribution hole are measured by the measuring plate 1. The weighed polymer stream is arranged by the distribution plate 2 so as to have a composite cross section of a single fiber, and the composite polymer stream formed by the distribution plate 2 is compressed by the discharge plate 3 and discharged.

In order to avoid confusion in the explanation of the composite base, although not shown, for the member laminated on the measuring plate 1, a member having a flow path may be used according to the spinning machine and the spinning pack. .. By designing the measuring plate 1 according to the existing flow path member, the existing spinning pack and the member can be utilized as it is.

Therefore, it is not necessary to monopolize the spinning machine especially for the mouthpiece. Further, in practice, it is preferable to stack a plurality of flow path plates between the flow path and the measuring plate or between the measuring plate 1 and the distribution plate 2. The purpose of this is to provide a flow path for efficiently transferring the polymer in the cross-sectional direction of the base and the cross-sectional direction of the single fiber, and to introduce the polymer into the distribution plate 2. The composite polymer flow discharged from the discharge plate 3 is cooled and solidified according to the above-mentioned production method, oiled, and taken up by a roller having a specified peripheral speed. After that, it is stretched with a heating roller to obtain a desired composite fiber.

In order to elute the innermost layer of the easily soluble polymer from the composite fiber of the present invention to obtain a hollow fiber composed of only the poorly soluble polymer, the composite fiber is immersed in a solvent or the like in which the easily soluble polymer can be dissolved. The easily soluble polymer may be removed. When the easily soluble polymer is a copolymerized polyethylene terephthalate or polylactic acid obtained by copolymerizing 5-sodium sulfoisophthalic acid or polyethylene glycol, an alkaline aqueous solution such as an aqueous sodium hydroxide solution can be used.

As a method of treating the composite fiber of the present invention with an alkaline aqueous solution, for example, after forming a fiber structure composed of the composite fiber, it may be immersed in the alkaline aqueous solution. At this time, it is preferable to heat the alkaline aqueous solution to 50 ° C. or higher because the progress of hydrolysis can be accelerated. Further, if a fluid dyeing machine or the like is used, a large amount of processing can be performed at one time, which is preferable from an industrial point of view.

Hereinafter, the composite fiber and the hollow fiber of the present invention will be specifically described with reference to examples.

The following evaluations were made for Examples and Comparative Examples.
A. Melt Viscosity of Polymer The chip-shaped polymer was measured with a water content of 200 ppm or less by a vacuum dryer, and the strain rate was changed stepwise by a capillograph manufactured by Toyo Seiki Co., Ltd. to measure the melt viscosity. The measurement temperature was the same as the spinning temperature, and the period from the injection of the sample to the heating furnace in the nitrogen atmosphere to the start of the measurement was 5 minutes, and the value of the shear rate 1216s ^-1 was evaluated as the melt viscosity of the polymer.

B. Melting point of polymer The chip-shaped polymer has a moisture content of 200 ppm or less by a vacuum dryer, weighs about 5 mg, and rises from 0 ° C to 300 ° C using a TA Instrument differential scanning calorimetry (DSC) Q2000 type. After raising the temperature at a temperature rate of 16 ° C./min, the temperature was maintained at 300 ° C. for 5 minutes for DSC measurement. The melting point was calculated from the melting peak observed during the heating process. The measurement was performed 3 times per sample, and the average value was taken as the melting point. When a plurality of melting peaks were observed, the melting peak top on the highest temperature side was taken as the melting point.

C. The weight of the fiber having a fineness of 100 m was measured, and the value was multiplied by 100 to calculate the value. This operation was repeated 10 times, and the value obtained by rounding off the second decimal place of the average value was defined as the fineness (dtex).

D. Cross-section parameters of composite fibers (RB / RA)
The composite fiber is embedded with an embedding agent such as epoxy resin, and the cross section of the fiber in the direction perpendicular to the fiber axis is photographed with a scanning electron microscope (SEM) manufactured by HITACHI at a magnification at which fibers of 10 filaments or more can be observed. I asked for it. By analyzing the fibers randomly extracted from each photographed image in the same image using WinROOF manufactured by Mitani Shoji Co., Ltd., the fiber surface and at least two points (for example, a1 and a2 in FIG. 2A). ), The diameter of the circle (for example, A) in FIG. 2 (a), which exists only inside the fiber and has the maximum diameter that can be taken in the range where the circumference of the inscribed circle and the fiber surface do not intersect. Calculated. A simple number average of the results obtained by performing this for 10 filaments was obtained, and the value rounded to the nearest whole number was taken as the inscribed circle diameter RA.

Further, the minimum possible range is that the circumscribed circle is circumscribed with the fiber surface at at least two points (for example, b1 and b2 in FIG. 2A) and exists only outside the fiber so that the circumference of the circumscribed circle and the fiber surface do not intersect. The diameter of a circle having the diameter of (for example, B in (a) of FIG. 2) was calculated. A simple number average of the results obtained by performing this for 10 filaments was obtained, and the value rounded to the nearest whole number was taken as the circumscribed circle diameter RB. The value obtained by dividing the RB obtained for each fiber by RA was calculated, the simple number average of the results obtained by performing this for 10 filaments was obtained, and the value rounded to the second decimal place was defined as RB / RA.

E. Fiber diameter Composite fibers and multifilaments are embedded with an embedding agent such as epoxy resin, and the cross section of the fibers in the direction perpendicular to the fiber axis is imaged as a magnification at which fibers of 10 or more filaments can be observed with a scanning electron microscope (SEM). I took a picture and asked for it. The area of fibers randomly extracted from each photographed image in the same image was measured, and the diameter obtained in terms of a perfect circle was measured in μm units up to the first decimal place. A simple number average of the results obtained by performing this for 10 filaments was obtained, and the value rounded to the first decimal place was taken as the fiber diameter (μm). Here, when a hollow portion is present in the cross section of the fiber in the direction perpendicular to the fiber axis, the area of the hollow portion is added to the area of the fiber.

F. Communication width The composite fiber was embedded with an embedding agent such as epoxy resin, and an image was taken at a magnification at which 10 or more fibers could be observed with a transmission electron microscope (TEM) in the cross section of the fiber in the direction perpendicular to the fiber axis. .. In the composite fiber of the obtained image, when the easily soluble polymer communicates from the fiber center to the fiber surface, it communicates through the fiber center G by analyzing using WinROOF manufactured by Mitani Shoji Co., Ltd. of computer software. Of the width W of the communication portion in the direction perpendicular to the straight line S parallel to the portion (for example, S in (c) of FIG. 3) (for example, W in (c) of FIG. 3), the shortest width is in μm units. Calculated. The result of doing this for 10 filaments was obtained as a simple number average, and the value rounded to the second decimal place was used as the communication width. Further, the division width obtained for each filament is divided by the fiber diameter and multiplied by 100 to calculate a simple numerical average of the results obtained by performing this for 10 filaments, and the value rounded to the nearest whole number is communicated with the fiber diameter. The width ratio (%) was used.

G. The flatness multifilament is embedded with an embedding agent such as epoxy resin, and the cross section of the fiber in the direction perpendicular to the fiber axis is imaged as a magnification at which 10 or more fibers can be observed with a scanning electron microscope (SEM) manufactured by HITACHI. I took a picture and asked for it. By analyzing the fibers randomly extracted from each photographed image in the same image using image analysis software, the distance is the longest among arbitrary points on the outer circumference of the fibers as shown in FIG. 5 (a). The long axis is the straight line (c1-c2) connecting two distant points (c1, c2), and the straight line (d1-d2) perpendicular to the long axis through the midpoint of the long axis is the short axis. It was calculated by dividing the length by the length of the minor axis. The result of doing this for 10 fibers was obtained as a simple number average, and the value rounded to the second decimal place was taken as the flatness.

H. Hollow ratio The multifilament is embedded with an embedding agent such as epoxy resin, and the cross section of the fiber in the direction perpendicular to the fiber axis is imaged as a magnification at which 10 or more fibers can be observed with a scanning electron microscope (SEM) manufactured by HITACHI. I took a picture and asked for it. If the fibers randomly extracted from each captured image in the same image have a hollow portion, the area and hollow portion obtained from the outer shape including the hollow portion of the fiber can be analyzed by using image analysis software. The area of each part was obtained, the area of the hollow part was divided by the area obtained from the outer shape including the hollow part of the fiber, and the value was calculated by multiplying by 100. A simple number average of the results obtained by performing this for 10 fibers was obtained, and the value rounded to the first decimal place was taken as the hollow ratio (%).

I. Width of the opening The multifilament is embedded with an embedding agent such as epoxy resin, and the cross section of the fiber in the direction perpendicular to the fiber axis is imaged as a magnification at which 10 or more fibers can be observed with a transmission electron microscope (TEM). I took a picture. When the fiber of the obtained image has an opening from the fiber center to the fiber surface, the straight line S passing through the fiber center G and being parallel to the opening is analyzed by using image analysis software. The shortest width among the width W'(for example, W'in (b) of FIG. 6) in the direction perpendicular to'(for example, S'in (b) of FIG. 6) was calculated in μm units. A simple number average of the results obtained by performing this for 10 filaments was obtained, and the value rounded to the second decimal place was taken as the width of the opening. Further, the width of the opening obtained for each filament is divided by the fiber diameter and multiplied by 100 to calculate a simple numerical average of the results obtained by performing this for 10 filaments, and the value rounded to the nearest whole number is the fiber diameter. The ratio of the width of the opening to the ratio of the width of the opening (ratio of the opening) (%) was used.

J. Number of crimped mountains (mountain / cm)
In a fabric made of multifilaments, the multifilaments are extracted from the fabric so as not to be plastically deformed, one end of the multifilaments is fixed, a load of 1 mg / dtex is applied to the other end, and after 30 seconds or more, the multifilaments are formed. Markings were made at arbitrary points where the distance between the two points in the fiber axis direction was 1 cm. After that, the fibers are separated from the multifilament so as not to be plastically deformed, adjusted so that the space between the markings attached in advance is 1 cm, and fixed on the slide glass, and this sample is 1 cm with a digital microscope. The image was taken at a magnification at which the marking of was observable. When the multifilament had a crimped form in which the fibers were twisted as shown in FIG. 11 in the captured image, the number of crimped ridges existing between the markings was determined. A simple number average was obtained as a result of performing this operation on 10 fibers composed of the same polymer, and the value rounded to the first decimal place was taken as the number of crimped peaks (mountain / cm).

K. Coefficient of variation of rotation angle of long axis CV
In a multifilament fabric, an image is taken at a magnification that allows 20 or more fibers to be observed with a scanning electron microscope (SEM) manufactured by HITACHI on the cross section of the fabric that is perpendicular to the length direction of the fabric and perpendicular to the fiber axis direction of the multifilament. did. When the fiber of the obtained image has a flat cross section, it is analyzed by using image analysis software, and as shown in FIG. 5B, any point on the outer circumference of the fiber is formed. The long axis is the straight line (c1-c2) connecting the two points (c1 and c2) that are farthest apart, and the long line is the straight line that passes through the midpoint of the long axis of the flat hollow fiber and is parallel to the lower side of the photographed image. It was rotated counterclockwise around the midpoint of the axis, and the rotation angle (θ) when the slope of the long axis and the slope of the straight line matched was evaluated. The standard deviation and the average value of the results of this evaluation performed on 20 fibers randomly selected from the multifilaments were obtained. The standard deviation was divided by the average value and multiplied by 100, and the value rounded to the first decimal place was taken as the coefficient of variation CV (%) of the rotation angle of the long axis.

L. Texture evaluation (lightweight, flexible, repulsive, smooth, rough)
The number of fibers was adjusted so that the cover factor (CFA) in the warp direction was 800 and the cover factor (CFB) in the weft direction was 1200, and a 3/1 twill woven fabric was produced. However, CFA and CFB referred to here mean that the warp density and weft density of the woven fabric are measured in a section of 2.54 cm according to JIS-L-1096: 2010 8.6.1, and CFA = warp density × ( It is a value obtained from the formula of (fineness of warp) ^1/2 , CFB = weft density × (fineness of weft) ^1/2 . After scouring, heat-treating, alkali-treating, and heat-setting the obtained woven fabric, five textures of light weight, flexibility, repulsion, smoothness, and roughness were evaluated using the following methods.

The feeling of lightness was evaluated by the following method. That is, using a constant pressure thickness measuring device (PG-14J) manufactured by Telotech, the thickness (cm) of a 20 cm × 20 cm fabric is measured under a constant pressure (0.7 kPa), the volume of the fabric is calculated, and then the said. The value obtained by dividing the weight (g) of the fabric by the obtained volume was taken as the apparent density of the fabric (g / cm ³ ). From the obtained apparent density, the lightness was judged in three stages based on the following criteria.

⊚: Excellent lightweight feeling (apparent density ≤ 0.34)
◯: Good lightness (0.34 <apparent density ≤ 0.44)
×: Inferior in lightness (0.44 <apparent density)

The flexibility was evaluated by the following method using a pure bending tester (KES-FB2) manufactured by Katou Tech. That is, a woven fabric of 20 cm × 20 cm was grasped with an effective sample length of 20 cm × 1 cm and bent in the weft direction under the condition of maximum curvature ± 2.5 cm ^-1 . At that time, the difference between the bending moments (gf · cm / cm) per unit width of curvature 0.5 cm ^-1 and 1.5 cm ^-1 divided by the curvature difference 1 cm ^-1 and the curvature -0.5 cm ^-1 . The average value of the values obtained by dividing the difference in bending moment (gf · cm / cm) per unit width of −1.5 cm ^-1 by the curvature difference 1 cm ^-1 was calculated. This operation is performed 3 times per location, and the result of performing this operation for a total of 10 ^locations is to obtain a simple number average. gf · cm ² / cm). From the obtained bending hardness B × ^10-2 , the flexibility was judged in three stages based on the following criteria.

⊚: Excellent flexibility (flexural rigidity B × 10 ^-2- ≦ 1.0)
◯: Good flexibility (1.0 <flexural rigidity B × 10 ^-2- ≦ 2.0)
×: Inferior in flexibility (2.0 <flexural rigidity B × 10 ^-2 )

The feeling of repulsion was evaluated by the following method. That is, when a woven fabric of 20 cm × 20 cm is grasped with an effective sample length of 20 cm × 1 cm using a pure bending tester (KES-FB2) manufactured by Kato Tech and bent in the warp direction, the curvature is ± 1.0 cm ^-1 . The width of the hysteresis (gf · cm / cm) was calculated. This operation was performed 3 times per location, and the result of performing this operation for a total of 10 ^locations was calculated as a simple number average.・ Cm / cm). From the obtained bending recovery 2HB × ^10-2 , the repulsive feeling was judged in 3 stages based on the following criteria.

⊚: Excellent repulsion feeling (bending recovery 2HB × 10 ^-2 ≦ 1.0)
◯: Good repulsion (1.0 <bending recovery 2HB × 10 ^-2 ≦ 2.0)
×: Poor repulsion (2.0 <bending recovery 2HB × 10 ^-2 )

The smoothness and roughness were evaluated by the following method. That is, using an automated surface tester (KES-FB4) manufactured by Katou Tech, a load of 50 g is applied to a 1 cm × 1 cm terminal wound with a piano wire in a range of 10 cm × 10 cm of a 20 cm × 20 cm fabric. By sliding at a speed of 0.0 mm / sec, the average friction coefficient MIU and the fluctuation MMD of the average friction coefficient were obtained. This operation was performed 3 times per location, and this was performed for a total of 10 locations. Regarding the result, a simple number average was obtained for the average friction coefficient MIU, and the value rounded to the second decimal place was used as the friction coefficient. From the obtained friction coefficient, the smoothness was judged in three stages based on the following criteria.

⊚: Excellent smoothness (coefficient of friction <0.5)
◯: Good smoothness (0.5 ≤ friction coefficient <1.0)
×: Inferior in smoothness (1.0 ≤ friction coefficient)

For the fluctuation MMD of the average friction coefficient, a simple number average was obtained, and the value rounded to the fourth decimal place was taken as the friction fluctuation. From the obtained friction fluctuation, the feeling of roughness was judged in three stages based on the following criteria.

◎: Excellent roughness (0.9 ≤ friction fluctuation)
◯: Good roughness (0.5 ≤ friction coefficient <0.9)
×: Inferior in roughness (friction coefficient <0.5)

M. Functional evaluation (water absorption and quick drying, stretchability)
The number of fibers was adjusted so that the cover factor (CFA) in the warp direction was 800 and the cover factor (CFB) in the weft direction was 1200, and a 3/1 twill woven fabric was produced. However, CFA and CFB referred to here mean that the warp density and weft density of the woven fabric are measured in a section of 2.54 cm according to JIS-L-1096: 2010 8.6.1, and CFA = warp density × ( It is a value obtained from the formula of (fineness of warp) ^1/2 , CFB = weft density × (fineness of weft) ^1/2 . After scouring, moist heat treatment, alkali treatment, and heat setting of the obtained woven fabric, two functions of water absorption and quick drying and stretchability were evaluated using the following methods.

The water absorption and quick-drying property were evaluated by the following method. That is, after 0.1 cc of water was dropped onto a 10 cm × 10 cm woven fabric, the weight of the woven fabric was measured every 5 minutes at a temperature of 20 degrees and a relative humidity of 65 RH%, and the residual moisture content was 1.0% or less. I asked for the time (minutes) to be. A simple number average was obtained as a result of performing this operation for a total of three locations, and the value rounded off to the nearest whole number was taken as the water diffusion time (minutes). From the obtained water diffusion time, the water absorption and quick-drying property were determined in three stages based on the following criteria.

⊚: Excellent water absorption and quick drying (moisture diffusion time ≤ 20)
◯: Good water absorption and quick drying (20 <moisture diffusion time ≦ 40)
X: Poor in water absorption and quick-drying (40 <moisture diffusion time)

Stretchability was evaluated by the following method. That is, it was carried out according to the elongation rate A method (constant speed elongation method) described in Section 8.16.1 of JIS L1096: 2010. The strip method with a load of 17.6 N (1.8 kg) was adopted, and the test conditions were a sample width of 5 cm × a length of 20 cm, a clamp interval of 10 cm, and a tensile speed of 20 cm / min. As the initial load, a weight equivalent to a sample width of 1 m was used according to the method of JIS L1096: 2010. A simple number average of the results of three tests conducted in the horizontal direction of the woven fabric was obtained, and the value rounded off to the nearest whole number was taken as the fabric elongation rate (%). From the obtained fabric elongation rate, the stretchability was determined in three stages based on the following criteria.

⊚: Excellent stretchability (15 ≤ elongation rate)
◯: Good stretchability (5 ≤ elongation rate <15)
×: Inferior in stretchability (elongation rate <5)

N. Abrasion resistance The number of fibers was adjusted so that the cover factor (CFA) in the warp direction was 1100 and the cover factor (CFB) in the weft direction was 1100, and a plain woven fabric was produced. The obtained woven fabric was dyed black with the disperse dye Sumikaron Black S-3B (10% owf). The dyed woven fabric was cut into a circle with a diameter of 10 cm, moistened with distilled water, and attached to a disk. Further, the woven fabric cut into 30 cm squares was fixed on a horizontal plate while being dried.

A disk with a woven material moistened with distilled water is brought into horizontal contact with the woven material fixed on a horizontal plate, and the center of the disk draws a circle with a diameter of 10 cm at a load of 420 g and a speed of 50 rpm. The disk was rotated for 10 minutes and the two fabrics were rubbed. After leaving it for 4 hours after the end of friction, the degree of discoloration of the woven fabric attached to the disk was judged to be grades 1 to 5 in 0.5 grade increments using a gray scale for discoloration. From the obtained grade judgment results, the wear resistance was judged in three stages based on the following criteria.

◎: Excellent wear resistance (class judgment: 4th grade or higher)
◯: Good wear resistance (class judgment: class 3 or 3.5)
×: Inferior in wear resistance (class judgment: less than 3rd grade)

[Example 1]
As the polymer 1, polyethylene terephthalate (SSIA-PEG copolymerized PET, melt viscosity: 100 Pa · s, melting point: 233 ° C.) in which 8 mol% of 5-sodium sulfoisophthalic acid and 9% by mass of polyethylene glycol were copolymerized was prepared.
As the polymer 2, polyethylene terephthalate (IPA copolymerized PET, melt viscosity: 140 Pa · s, melting point: 232 ° C.) obtained by copolymerizing 7 mol% of isophthalic acid was prepared.
Polyethylene terephthalate (PET, melt viscosity: 130 Pa · s, melting point: 254 ° C.) was prepared as the polymer 3.

After melting these polymers separately at 290 ° C., the polymer 1 / polymer 2 / polymer 3 is weighed to a weight ratio of 20/40/40, and the spinning pack incorporating the composite base shown in FIG. Inflowed into. In the flat composite fiber as shown in FIG. 3A, the polymer 1 is arranged in the innermost layer and the communication portion from the fiber center to the fiber surface, and the polymer 2 and the polymer 3 are in a side-by-side type in the outermost layer. The inflow polymer was discharged from the discharge holes so as to form a bonded composite structure.

A 56 dtex-36 filament (fiber diameter 12 μm) was applied to the discharged composite polymer stream after cooling and solidifying, winding at a spinning speed of 1500 m / min, and stretching between rollers heated to 90 ° C and 130 ° C. The composite fiber of was manufactured.

The ratio RB / RA of the inscribed circle diameter RA and the circumscribed circle diameter RB of the obtained composite fiber was 1.8. Further, the communication width was 0.5 μm, which was 4% of the fiber diameter of 12 μm, and it was confirmed that the composite fiber of the present invention was used.

The obtained composite fiber was woven, subjected to a scouring treatment at 80 ° C. and a wet heat treatment at 130 ° C., and then heated to 90 ° C. in a 1% by mass sodium hydroxide aqueous solution (bath ratio 1:50). By the treatment, 99% or more of the polymer 1 which is an easily soluble polymer was removed. At this time, due to the presence of the communication portion from the center of the fiber to the surface of the fiber, the polymer 1 in the innermost layer was rapidly eluted within 10 minutes after the start of the elution treatment.

Then, by applying a heat set at 180 ° C., a multifilament composed of flat hollow fibers having a flatness of 1.8, a hollow ratio of 18%, and a number of crimped ridges of 17 ridges / cm as shown in FIG. 2 (b). A woven fabric composed of was obtained. Further, the flat hollow fiber had an opening, and the width of the opening was 0.5 μm, which was 4% of the fiber diameter.

The woven fabric composed of the multifilament had a coefficient of variation CV of the rotation angle of the long axis of 27% in the flat hollow fibers in the multifilament. Therefore, the unevenness of the long axis direction of the cross section caused unevenness on the textile surface. As a result, when you touch the surface of the fabric, you will feel a smooth feel (friction coefficient: 0.3) but a smooth feel due to the large roughness (friction fluctuation: 0.9 × ^10-2 ). Was made. Furthermore, in the woven fabric, complicated voids are created between the fibers, and in combination with the hollow portion inside the fibers, an appropriate repulsive feeling (bending recovery 2HB: 0.9 × ^10-2 gf · cm / cm) and swelling (apparent density) are created. : 0.33 g / cm ³ ) and had a soft texture (bending hardness B: 0.9 × 10 ^-2 gf · cm ² / cm). In addition, the woven fabric has excellent stretchability (fabric elongation rate: 16%) and water absorption and quick-drying property (moisture diffusion time: 25 minutes) due to the presence of openings, which is directly linked to human comfort. It was a woven fabric with excellent wearing comfort that had both texture and function.

Further, since the opening of the woven fabric is narrow, not only the voids inside the fibers are maintained without being crushed even after the processing of the woven fabric, but also the functional agent that has entered the hollow portion when the functional agent is applied is washed. It did not fall off due to such factors, and the performance and durability of the functional agent was greatly improved. It was also found that the woven fabric had good abrasion resistance (frosting: 4th grade) without discoloration due to fibrillation due to the opening. The results are shown in the table below.

[Examples 2 and 3]
All were carried out according to Example 1 except that the cross-sectional shape was changed to a multi-leaf shape (Example 2) as shown in FIG. 3 (b) and a flat multi-leaf shape (Example 3) as shown in FIG. 3 (c).

In Example 2, unevenness was formed on the fiber surface, so that uneven reflection of light suppressed uneven gloss (glare) of the fabric, and fine interfiber voids enhanced water absorption and quick-drying.

In Example 3, the flat and multi-leaf shape combines the complex interfiber voids caused by twisting the flat and the fine inter-fiber voids due to the unevenness of the fiber surface due to the multi-leaf shape, resulting in a feeling of lightness and repulsion. Functions such as texture and quick-drying water absorption were further improved. The results are shown in the table below.

[Example 4]
All were carried out according to Example 1 except that the composite structure was changed to a structure in which the easily soluble polymer was present in the outermost layer as shown in FIG. 3D.

In Example 4, due to the effect of the interfiber voids generated when the easily soluble polymer of the outermost layer is removed, the fibers fixed at the binding point of the woven or knitted fabric can move, so that the flexibility is improved and the porosity is high. The feeling of lightness was improved by the decrease in the apparent density of. The results are shown in the table below.

[Examples 5 and 6]
RB / RA (deformation degree), which is the ratio of the inscribed circle diameter RA and the circumscribed circle diameter RB of the fiber, is RB / RA = 1.3 (Example 5), and RB / RA = as shown in FIG. 1 (c). Everything was carried out according to Example 1 except that it was changed to 1.0 (Example 6).

In Examples 5 and 6, as the degree of deformation becomes smaller, the effect of steric hindrance when twisted becomes smaller, so that the feeling of roughness is reduced, while the crimped morphology developed by the heat treatment becomes finer. By approaching the coil shape, not only the stretchability is increased, but also the fine interfiber voids are increased and the flexibility is also improved. The results are shown in the table below.

[Example 7]
The cross-sectional shape of the composite fiber is a cross-sectional shape in which the bonding surface and the communicating portion of polymers having different melting points are on a straight line, and the direction (angle) of the straight line is random (the four types in FIG. 10 are examples of the cross-sectional shape). ), Except for the change, all were carried out according to Example 1.

In Example 7, the crimping morphology developed by the heat treatment differs for each single fiber due to the difference in the distance between the centers of gravity, so that the coefficient of variation CV of the rotation angle of the long axis also increases, and the feeling of roughness is strengthened. Not only was the tactile sensation more pronounced, but the lightweight feel was also improved by increasing the interfiber voids. The results are shown in the table below.

[Comparative Example 1]
This was carried out according to Example 1 except that the polymer 2 was changed to the same PET as the polymer 3.

In Comparative Example 1, although a certain light weight feeling can be obtained by the hollow portion inside the fiber, since the crimped morphology does not appear, there is no unevenness on the textile surface, the feeling of roughness is lacking, and the interfiber gaps. However, it lacked flexibility and repulsion. In addition, it did not have functions such as water absorption and quick drying and stretchability. The results are shown in the table below.

[Comparative Example 2]
After stretching, the number of false twists is 3000 T / m using a friction disc while heating with a heater set at 180 ° C. between rollers with a processing speed of 250 m / min and a draw ratio of 1.05 times. All were carried out according to Comparative Example 1 except that the false twisting process was performed at the rotation speed.

In Comparative Example 2, although the crimped form was obtained by false twisting, the unevenness of the textile surface became monotonous and lacked a rough feeling. The results are shown in the table below.

[Comparative Example 3]
The composite structure was carried out according to Example 1 except that the composite structure was changed to a structure in which round, sparingly soluble polymers having different melting points were laminated in the direction from the fiber center toward the fiber surface as shown in FIG. 4 (b).

In Comparative Example 2, although a certain lightweight feeling can be obtained by forming voids inside the fiber by removing the easily soluble polymer in the innermost layer, the poorly soluble polymers having different melting points are not unevenly distributed and are subjected to heat treatment. Since the crimped morphology was hardly expressed, it lacked flexibility, repulsion, and roughness, and did not have functions such as water absorption and quick drying and stretchability. The results are shown in the table below.

[Comparative Example 4]
Polyethylene terephthalate (IPA copolymer PET, melt viscosity: 140 Pa · s, melting point: 232 ° C.) in which 7 mol% of isophthalic acid is copolymerized as polymer 2, and polyethylene terephthalate (PET, melt viscosity: 130 Pa · s, melting point: 254) as polymer 3. ℃) was prepared.

After melting these polymers separately at 290 ° C., the polymer 2 / polymer 3 is weighed so as to have a weight ratio of 50/50 to obtain a hollow composite fiber as shown in FIG. 4 (a). The inflow polymer was discharged from the discharge holes so as to have a hollow ratio of 20% and a composite structure in which the polymer 2 and the polymer 3 were joined in a side-by-side manner.

A 56dtex-36 filament (fiber diameter 13 μm) was applied to the discharged composite polymer stream after cooling and solidifying, winding at a spinning speed of 1500 m / min, and stretching between rollers heated to 90 ° C and 130 ° C. The composite fiber of was manufactured.

The obtained composite fiber was woven, subjected to a scouring treatment at 80 ° C. and a wet heat treatment at 130 ° C., and then a heat set was applied at 180 ° C. to obtain a woven fabric composed of the above composite fiber.

In Comparative Example 4, since the fiber already has a hollow inside at the time of fiber production, the hollow is crushed by the occurrence of crimping due to the weaving process or heat treatment, and the lightness is only impaired when the fiber is made into a woven fabric. However, it lacked flexibility and repulsion. The results are shown in the table below.

[Examples 8 and 9]
All were carried out according to Example 1 except that the communication width of the easily soluble polymer was changed to 8% (Example 8) and 16% (Example 9) with respect to the fiber diameter.

In Examples 8 and 9, the larger the opening formed after the removal of the easily soluble polymer, the more the friction coefficient increases due to the opening being caught by the finger when touched by hand, and water droplets are dropped. By increasing the surface area of the fiber in contact with the water droplets, the water absorption and quick-drying property were also improved. The results are shown in the table below.

[Examples 10 and 11]
All were carried out according to Example 1 except that the weight ratio of the polymer 2 / polymer 3 was changed to 60/20 (Example 10) and 20/60 (Example 11).

In Examples 10 and 11, the larger the ratio of the polymer 2 on the high shrinkage side, the stronger the crimped morphology was expressed, and the lighter the weight of the obtained woven fabric was. Further, as the amount of the polymer 3 which is a low shrinkage component was increased, clogging due to a high shrinkage rate on the high shrinkage side in the heat set was suppressed, and the flexibility was excellent. The results are shown in the table below.

[Examples 12 and 13]
All were carried out according to Example 1 except that the weight ratio of Polymer 1 / Polymer 2 / Polymer 3 was changed to 10/45/45 (Example 12) and 30/35/35 (Example 13).

In Examples 12 and 13, when the weight ratio of the polymer 3 was reduced and the hollow ratio was reduced, the bending hardness was increased, so that a characteristic elastic tactile sensation could be obtained. Further, when the weight ratio of the polymer 3 is increased to increase the hollowness ratio, the amount of air contained in the fiber increases, so that not only the feeling of lightness is increased, but also the flexibility and the feeling of repulsion are excellent. The results are shown in the table below.

[Examples 14 and 15]
All were carried out according to Example 1 except that the discharge amount was changed so that the fiber diameter was 17 μm (Example 14) and 24 μm (Example 15).

In Examples 14 and 15, by increasing the fiber diameter, the loop of the crimped form developed by the heat treatment becomes large, and in addition to improving the feeling of roughness and light weight, the bending hardness becomes large. , A characteristic elastic tactile sensation was obtained. The results are shown in the table below.

[Example 16]
All were carried out according to Example 1 except that the polymer 3 was changed to polyethylene terephthalate (PET containing TiO ₂ ) containing 5.0% by mass of titanium oxide.

In Example 16, when the easily soluble polymer is removed, titanium oxide deposited on the surface of the polymer 3 also falls off to create irregularities on the surface, and diffuse reflection of light causes reflection by the incident angle of light. Not only the change in the appearance of the fabric such as the ability to suppress the increase / decrease (glare) of the fiber, but also the functionality such as see-through protection and UV shielding can be obtained by the titanium oxide inside the fiber. The results are shown in the table below.

[Example 17]
All were carried out according to Example 1 except that the polymer 2 was changed to polypropylene terephthalate (PPT).

In Example 17, in combination with the rubber elasticity characteristics of PPT, not only the texture having a lighter feeling and more excellent flexibility was exhibited, but also the stretching function was significantly improved. Further, since PPT has a low refractive index as compared with PET, the obtained woven fabric is also excellent in color development. The results are shown in the table below.

[Example 18]
As polymer 1, 8 mol% of 5-sodium sulfoisophthalic acid and 9% by mass of polyethylene glycol were copolymerized with polyethylene terephthalate (SSIA-PEG copolymerized PET, melt viscosity: 100 Pa · s, melting point: 233 ° C.), and polymer 2 was nylon. Prepare a 6-nylon 66 copolymer (N6-66 copolymer, melt viscosity: 240 Pa · s, melting point: 195 ° C.) and nylon 6 (N6, melt viscosity: 190 Pa · s, melting point: 223 ° C.) as the polymer 3. did.

After melting these polymers separately at 280 ° C., the polymer 1 / polymer 2 / polymer 3 is weighed to a weight ratio of 20/40/40, and the spinning pack incorporating the composite base shown in FIG. Inflowed into. The flat composite fiber as shown in FIG. 2A has a composite structure in which the polymer 1 is arranged in the innermost layer and the polymer 2 and the polymer 3 are joined in a side-by-side manner in the outermost layer. The inflow polymer was discharged from the discharge hole.

A 56 dtex-36 filament (fiber diameter 12 μm) was applied to the discharged composite polymer stream after cooling and solidifying, winding at a spinning speed of 1500 m / min, and stretching between rollers heated to 90 ° C and 130 ° C. The composite fiber of was manufactured.

The obtained composite fiber was woven, subjected to a scouring treatment at 80 ° C. and a wet heat treatment at 130 ° C., and then heated to 90 ° C. in a 1% by mass sodium hydroxide aqueous solution (bath ratio 1:50). By the treatment, 99% or more of the polymer 1 which is an easily soluble polymer was removed. Then, by applying a heat set at 180 ° C., a multifilament composed of flat hollow fibers having a flatness of 1.8, a hollow ratio of 20%, and a number of crimped ridges of 12 ridges / cm as shown in FIG. 6 (a). A woven fabric composed of was obtained.

In Example 18, in combination with the characteristics of nylon having a low density and low elasticity as compared with polyester, not only an excellent lightweight feeling was obtained, but also a more flexible texture was exhibited. The results are shown in the table below.

The meanings of the abbreviations in the table are as follows.
PET: Polyethylene terephthalate PEG: Polyethylene glycol SSIA: 5-Sodium sulfoisophthalic acid IPA: Isophthalic acid PPT: Polypropylene terephthalate N6: Nylon 6
N6-66 Copolymer: Nylon 6-Nylon 66 Copolymer TiO ₂ : Titanium Oxide

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on August 18, 2020 (Japanese Patent Application No. 2020-137899) and a Japanese patent application filed on November 24, 2020 (Japanese Patent Application No. 2020-194085). Is taken in as a reference.

The composite fiber, hollow fiber and multifilament of the present invention have a textile having excellent wearing comfort that realizes an appropriate repulsive feeling and a soft texture with a bulge by precisely controlling the void structure inside the fiber and between the fibers. can get. Therefore, the composite fiber, hollow fiber and multifilament of the present invention can be used for general clothing such as jackets, skirts, pants and underwear, as well as sports clothing and clothing materials, as well as interior products such as carpets and sofas by taking advantage of their comfort. , Car seats and other vehicle interiors, cosmetics, cosmetic masks, health products and other daily uses, etc., can be suitably used for a wide range of textile products.

x: Easily soluble polymer y: Low melting point side poorly soluble polymer z: High melting point side poorly soluble polymer a1, a2: Intersection point b1 and b2 between fiber surface and inscribed circle: Intersection point c1 between fiber surface and circumscribing circle , C2: Two points on the outer circumference of the fiber and the farthest distance d1, d2: A straight line on the outer circumference of the fiber and perpendicular to the midpoint of the straight line connecting the two points most distant from each other and the surface of the fiber. Intersection A: A circle that is inscribed at least at two points on the fiber surface, exists only inside the fiber, and has the maximum diameter that can be taken within the range where the circumference of the inscribed circle does not intersect the fiber surface. B: At least the fiber surface. A circle that is circumscribing at two points and has the smallest diameter that exists only inside the fiber and has the smallest possible diameter in the range where the circumference of the extrinsic circle does not intersect the fiber surface. Of the straight lines that evenly divide the fiber cross section into two, the area ratio of the sparingly soluble polymer on the high melting point side and the sparingly soluble polymer on the low melting point side in the left and right or upper and lower fiber cross sections with the straight line as the boundary is either. A straight line S: a straight line that passes through the fiber center G and is parallel to the communication portion W: a straight line that is 100: 0 to 70:30 in the fiber cross section of Width of communication portion in the direction perpendicular to S S': Straight line W'that is parallel to the opening through the fiber center G: Width of the opening in the direction perpendicular to the straight line S'1: Measuring plate 2: Distributing Plate 3: Discharge plate

Claims (10)

In the cross section of the fiber, two or more kinds of polymers having different dissolution rates in a solvent are laminated from the center of the fiber toward the surface of the fiber.
The innermost layer containing the fiber center contains an easily soluble polymer, and the innermost layer contains the easily soluble polymer.
A composite fiber in which two types of sparingly soluble polymers having different melting points are unevenly distributed in at least one layer other than the innermost layer. The composite fiber according to claim 1, wherein the relationship between the inscribed circle diameter RA and the circumscribed circle diameter RB of the fiber is 1.2 ≦ RB / RA ≦ 2.4 in the fiber cross section. The composite fiber according to claim 1 or 2, wherein in the cross section of the fiber, the easily soluble polymer communicates from the center of the fiber to the surface of the fiber, and the communication width is 10% or less of the fiber diameter. The composite fiber according to any one of claims 1 to 3, wherein the outermost layer contains the easily soluble polymer in the cross section of the fiber. Hollow fiber from which the easily soluble polymer has been removed from the composite fiber according to any one of claims 1 to 4. It is a multifilament containing flat hollow fibers and is a multifilament.
A multifilament having a coefficient of variation CV of 15 to 50% for the rotation angle of the long axis of the flat hollow fiber. The multifilament according to claim 6, wherein the flat hollow fiber has a flatness of 1.2 or more in the cross section of the fiber. The multifilament according to claim 6 or 7, wherein the flat hollow fiber is composed of at least two kinds of polymers having different melting points in the cross section of the fiber. The flat hollow fiber has an opening from the center of the fiber toward the surface of the fiber.
The multifilament according to any one of claims 6 to 8, wherein the width of the opening is 10% or less of the fiber diameter. A textile product partially containing the composite fiber according to any one of claims 1 to 4, the hollow fiber according to claim 5, or the multifilament according to any one of claims 6 to 9.

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