JP6897085B2 - Split type composite fiber - Google Patents

Description

The present invention relates to a composite fiber capable of easily peeling and splitting by physical impact, heat treatment, or the like to generate ultrafine fibers, and is suitable for manufacturing a high-performance filter or a high-performance wiper that collects fine dust. It relates to a composite fiber.

The development of sheet-like materials such as filters for the purpose of cleaning the environment and non-woven fabrics for the sophistication of industrial and household wiping is progressing, and characteristics such as increased specific surface area and high frictional force are being developed to improve performance. Ultra-fine fibers with a surface area are used.

As a method for obtaining such ultrafine fibers, a direct spinning method typified by melt blowing and electrospinning, and a method using a sea-island type or split type composite fiber are widely used.

The direct spinning method is a highly productive manufacturing method because the generated ultrafine fibers are directly collected in the form of a sheet, and only one step is required from spinning to sheeting. Among them, melt blow, which produces ultrafine fibers by pulling a molten polymer with a high-temperature air flow, is widely used as a method for manufacturing ultrafine fiber non-woven fabrics, but the sheet obtained here is composed only of ultrafine fibers and has low mechanical properties. Therefore, when actually using it, it was necessary to combine it with other base materials.

In recent years, electrospinning has been attracting attention as a method for producing nanofiber non-woven fabrics. In this production method, the polymer solution or melt can be blown off by electrostatic force, and the nanofibers can be accumulated at the collector portion to form a sheet. However, it is used by blowing off a solution in which at most several% of the resin is dissolved, and the productivity is extremely low as compared with other methods. In addition, although the obtained fiber can be made relatively thin, it has low mechanical properties and has a problem of being combined with other base materials as described above, and further, a recovery facility for the solvent used in the undiluted solution of nanofiber is required. In some cases.

In the method using a sea-island type composite fiber, a polymer of a plurality of components is used for spinning to obtain a sea-island composite fiber having a cross section in which a plurality of island components are scattered in the sea component, and then the sea component is used as a solvent or the like. By dissolving and removing with, ultrafine fibers derived from island components can be obtained. With the advancement of the base technology for forming the sea-island cross section, it is possible to form nano-order island components, and very fine fibers can be obtained. However, even in this case, it is necessary to combine it with other materials from the viewpoint of the mechanical properties of the sheet. In addition, since a solvent is used to elute the sea component, the type of base material to be combined may be limited due to the functional agent or the like charged in the ultrafine fibers falling off. In order to generate ultrafine fibers from sea-island type composite fibers, special equipment for dissolving, removing and cleaning sea components is also required.

The method using the split type composite fiber is the same as the Kaijima type in that the composite fiber is obtained by spinning using a polymer having a plurality of components. Here, in order to facilitate the peeling division, incompatible polymers are used in combination, or a peeling accelerator is added to the polymer. In the case of such a split type composite fiber, a large number of ultrafine fibers are generated by causing interfacial peeling between the components by utilizing the shrinkage difference of the polymer with respect to physical impact, heat and chemicals. For this reason, any of the polymers that make up the composite fiber can be used without being discarded, and the production of ultrafine fibers can be handled by using existing processes or adding simple equipment, making it suitable for high-performance filters and wipers. It is suitable for obtaining raw yarn, and further, the fibers having a high fineness generated after division can be used as the skeleton of the sheet as it is, together with the ultrafine fibers. Therefore, there is a possibility that the combination with another base material serving as a support material can be omitted.

Various developments have been made for this split-type composite fiber. For example, in Patent Document 1, the split is promoted by permeating a chemical. After heat-treating a split-type composite fiber in which a petroleum resin is added to a low melting point component having a large heat shrinkage rate, it is immersed in a solvent soluble in the petroleum resin (solvent treatment) and pressed to improve the splittability. It is improving. For this reason, the number of production processes increases, such as the need for solvent treatment, and special equipment such as collecting the solvent is required. Further, since the press treatment is performed during the division treatment, the non-woven fabric tends to have a high density, and it is difficult to manufacture the non-woven fabric used for applications requiring bulkiness.

Patent Document 2 discloses a split-type composite fiber having a hollow portion in the cross section of the fiber and combining a polypropylene-based resin and a polyethylene-based resin. Having a hollow cross section enhances the peelability between the two components, and a method of dividing by using a physical impact such as a water jet is exemplified. However, in Patent Document 2, the number of divisions is limited, and the fine fibers generated after the division are naturally limited to those having a large fiber diameter.

Further, Patent Document 3 discloses a split type composite fiber in which incompatible polymers are combined and the composite spinneret is divided into structural units having 50 or more polygonal shapes by a method of dividing the composite spinneret into multiple stages. There is. It is true that the ultrafine fibers obtained by the split-type composite fibers are those having a very fine fiber diameter region, but the sizes of the generated ultrafine fibers are not uniform, and the fiber length is about several cm, which is high. In applications such as performance filters that require a precise non-woven fabric design, the size of the generated ultrafine fibers is not sufficiently controlled.

JP-A-9-31755 (Claims) Japanese Unexamined Patent Publication No. 2002-220740 (Claims) JP-A-5-25710 (Claims)

An object of the present invention is to solve the above-mentioned problems of the prior art, and the split type composite fiber of the present invention is a split type composite fiber capable of easily generating ultrafine fibers by heat or physical treatment. To provide.

The above object is achieved by the following means.

(1) In the fiber cross section in the direction perpendicular to the fiber axis, the polymers A and B are composite fibers in which the polymers A and B are alternately arranged while being exposed on the fiber surface, and the polymer A forms one continuous segment a, and the polymer. B is a split-type composite fiber composed of a plurality of segments b , having a segment b2 in which the average area of the segment b is 0.01 to 4.0 μm ² and the area is 2.5 times or more the average area of the segment b. ..
( Segment b2 is one continuous segment without intrusion of segment a.)

(2) The split type composite fiber according to (1), wherein the average major axis of the segment b is 0.1 to 3.0 μm.

( 3 ) A textile product in which the split-type composite fiber according to (1) or (2) constitutes at least a part.

The split-type composite fiber of the present invention is excellent in process passability without generating fluff or the like in a higher-order process, and can easily generate ultrafine fibers and thick fine fibers by thermal treatment or physical treatment. ..

FIG. 1 is a cross-sectional view of the split type composite fiber of the present invention. FIG. 2 is a cross-sectional view of the split type composite fiber of the present invention having a hollow portion. FIG. 3 is a schematic view for showing the degree of deformation in the fiber cross section. FIG. 4 is a diagram showing the shape of the discharge hole of the base used for forming the hollow cross-section fiber. FIG. 5 is a cross-sectional view of a split type composite fiber in which the segment a is divided by the segment b2.

Hereinafter, the present invention will be described in detail together with desirable embodiments.
In the split type composite fiber of the present invention, it is necessary that the polymers A and B constituting the composite fiber are alternately arranged while being exposed on the fiber surface in the fiber cross section in the direction perpendicular to the fiber axis. FIG. 1 shows a cross-sectional view of the split type composite fiber of the present invention as an example. Since at least a part of each polymer is exposed on the fiber surface, an impact force is applied to the composite fiber to form each polymer. When peeling occurs at the interface of the segments to be formed, there is an effect that each segment is easily divided and becomes independent. Further, when an external impact is applied to the composite fiber, the external force is easily transmitted directly to the interface of the segment formed by each polymer, so that the peeling division is promoted.

It is necessary that the polymer A constituting the split type composite fiber of the present invention forms one continuous segment a, the polymer B forms a plurality of segments b, and the average area of the segments b is 8.0 μm ² or less. Is.

The segment a or b in the present invention means a region composed of the polymer A or B in the fiber cross section in the direction perpendicular to the fiber axis of the split type composite fiber. In the fiber cross-section example of FIG. 1, the portion 1 in the figure refers to the segment a and the portion 2 in the figure refers to the segment b. Further, one continuous segment in the present invention means that the segment a is not completely divided by another segment. For example, as shown in the portion 1 in FIG. 1, the segment a is a continuous region. Consists of. By forming one continuous segment a of the polymer A, the cross-sectional area is larger than that of the plurality of segments b made of the polymer B, and the fibers have a high fineness after division. It will be responsible for the function. Non-woven fabric sheets made of ultrafine fibers are often used in filters and wipers to improve their performance, but such sheets have low rigidity by themselves and are combined with support materials or mixed with thick fibers. Therefore, it is common to have rigidity that can withstand practical use. Therefore, there is no particular problem even if the split-type composite fiber of the present invention contains the ultrafine fiber generated by peeling and splitting and the split fiber derived from segment a in a mixed state in the sheet, rather than the ultrafine fiber. Since it has a large diameter, it contributes to the support of the non-woven fabric sheet.

Further, since the average area of the segment b composed of the polymer B is 8.0 μm ² or less, the characteristics such as high friction and increase in specific surface area unique to the ultrafine fiber are exhibited after the division, which is excellent. It becomes possible to make a non-woven fabric having a function.

In order to improve the function peculiar to the ultrafine fibers after division, it is possible to increase the specific surface area, that is, to reduce the diameter of the segment b, and the average area of the segment b referred to in the present invention is 6.0 μm ² or less. If the average area is 4.0 μm ² or less, the performance of substance adsorption and filtration collection will be dramatically improved when applied to a filter medium for a filter, and thus it can be mentioned as a particularly preferable range. .. ^{The practical lower limit of the area of the segment b is 0.01 μm 2} from the viewpoint of enabling division into ultrafine fibers after the non-woven fabric.

Further, for the purpose of the present invention, it is preferable that the amount of the fine fibers after division is large, and ^{the number of segments b having an area of 8.0 μm 2} or less is 25% or more of the total number of segments b. It is preferable, and if it is 50% or more of the total number of segments b, it can be applied to a non-woven fabric that requires collection of fine dust on the order of nanometers and super-mirror finish, and thus can be listed as a more preferable range. .. At this time, it goes without saying that the smaller the area of the segment b and the higher the blending amount of the minimized segment, the more effective it is for dust collection and wiping, but in consideration of the balance with other characteristics. , It is preferable to adjust.

In the split type composite fiber of the present invention, the average major axis of the segment b is preferably 5.0 μm or less in the fiber cross section in the direction perpendicular to the fiber axis. The major axis in the present invention means the distance of the longest straight line among the straight lines connecting the contours of each segment region.

When the average major axis of the segment b is 5.0 μm or less, it becomes difficult for the impact in the processing process to propagate to the entire composite fiber, which leads to suppression of peeling and division, so that the process passability is well ensured. It is preferable from the viewpoint of Further, from the viewpoint of promoting stabilization of process passability, the average major axis of the segment b is more preferably 4.0 μm or less, and the shorter segment major axis reduces the aspect ratio of the ultrafine fibers generated after division. , It becomes easy to face in a random direction, and it becomes easy to evenly disperse the ultrafine fibers in the sheet when the non-woven fabric is formed. Therefore, in applications such as filters where the structure inside the sheet affects the performance, the average major axis of the segment b is more preferably 3.0 μm or less from the viewpoint of enhancing the performance. The substantially lower limit of the average major axis of the segment b is 0.1 μm.

The split type composite fiber of the present invention preferably has a segment b2 having an area equal to or more than twice the average area of the segment b in the fiber cross section in the direction perpendicular to the fiber axis. For example, by having a segment having a large area such as segment b2 as shown in the portions 2 and 3 in FIG. 1, asymmetry occurs in the fiber cross section, stress at the time of division is difficult to disperse, and division is easy to proceed. Become. Further, since the area of the segment b2 is 2.0 times or more the average area of the segment b, stress at the time of division is likely to be applied to the segment b2, and the segment b2 is preferentially removed in the fiber cross section. A movable space is created, and the remaining segments are easily detached.

As the number of divisions of the finely divided segments in the fiber cross section increases, the contact area with the core portion that divides the segments increases, so that the adhesive force due to the anchor effect increases and the peeling division is suppressed. Tend to be. Therefore, as a result of diligent studies, the inventors have made a structure in which a large-sized division starting point is formed in the fiber cross section to create a space after the division starting point is removed, so that the core portion is easily distorted and becomes fine. It was found that the peeling division at the boundary between the divided segment and the core portion is promoted. From the viewpoint of securing a movable space that promotes peeling and division, the area of the segment b2 is more preferably 2.5 times or more, more preferably 3.0 times or more the average area of the segment b. Due to the remarkable size difference between the segment b2 and the segment b other than b2, the stress applied to the boundary between the segments becomes larger than that of other parts of the fiber, and the segment b2 portion is easily detached. As a result, a movable space is created, and the peeling division of the finely divided portion is promoted. ^{Here, the practical upper limit of the area of the segment b2 is 200 μm 2} from the viewpoint of achieving both the passability of the silk reeling process and the splittability into the ultrafine fibers after the non-woven fabric.

In the split-type composite fiber of the present invention, the arrangement of the segment b is not particularly limited as long as it is arranged alternately with the segment a while a part of the segment b is exposed on the fiber surface layer, but it enhances the splittability of the composite fiber. From the viewpoint, it is preferable that the major axis of the segment b is radially arranged from the surface layer toward the center of the cross section in the fiber cross section in the direction perpendicular to the fiber axis. By arranging the major axis radially in the cross section of the fiber, it becomes easy to be distorted due to the shrinkage difference when the heat treatment is applied, and as a result, the effect of facilitating the progress of the peeling division can be obtained.

Further, from the viewpoint that the split-type composite fiber of the present invention exhibits good splittability, when a split treatment such as heat treatment or physical impact is applied, the segment b2 having a large area is the earliest among the segments b made of the polymer B. It is important to peel off to create a movable space. The effect can be further exerted by exposing the segment b2 to the fiber surface. The shape of the segment b corresponding to the split segment is not particularly limited, but the shape of the segment b is also a factor that affects the peeling and splitting property, and the contact length between the segment b and the segment a in the fiber cross section is The shape is preferably as small as possible. Specific examples include a fan shape and a similar shape. For example, since the segment b has a fan shape, there are only two sides in contact with the segment a, the adhesive force at the interface is reduced, and the segment b portion expands toward the fiber surface layer. Therefore, when it receives an external force, it has a structure that easily moves outward and easily comes off.

The split type composite fiber of the present invention preferably has a hollow portion in the fiber cross section in the direction perpendicular to the fiber axis, and the hollow ratio is 5 to 30%. The hollow ratio referred to here means that after cutting a fiber having a hollow cross section, the cut surface is photographed two-dimensionally with an electron microscope (SEM) at a magnification at which 10 or more fibers can be observed. Ten fibers randomly selected from the captured image are extracted, the areas of the fibers and the hollow portion are measured using image processing software, and the area ratio is obtained. All of the above values were measured for each image at 10 locations, and the average value of the 10 images was taken as the hollow ratio of the hollow cross-section fiber of the present invention. Further, in order to easily evaluate this hollowness ratio, the side surface of the fiber is observed with a microscope or the like, and the fiber diameter converted to a round cross section is measured from the image. It is also possible to calculate the hollow ratio by evaluating the ratio of the measured fineness (measured weight) to the fineness (converted weight) converted as a solid fiber from the fiber diameter.

FIG. 2 shows a cross-sectional view of the split type composite fiber of the present invention having a hollow portion as an example, and the portion 4 in the figure points to the hollow portion. By having a hollow portion in the cross section of the fiber, the structure becomes asymmetrical in the cooling process in spinning, so that the composite fiber is liable to be distorted by applying heat treatment or physical impact. For this reason, the adhesive force of the split segment is reduced, the external force is easily received, and the peeling split is more likely to proceed, which is preferable. Further, when the hollow ratio is in the range of 5 to 30%, it is possible to ensure the splittability in the post-treatment while suppressing the peeling split in the silk reeling process. From the viewpoint of promoting peeling and splitting by an external force, the larger the area of the hollow portion in the fiber cross section, the easier it is for the fiber to be deformed and the peeling and splitting to proceed, and the hollow ratio is more preferably 10% or more. Further, the hollow ratio is more preferably 15% or more from the viewpoint of good division even when the split type composite fiber is fixed in the sheet so as to be heat-bonded with a binder or the like. On the other hand, from the viewpoint of maintaining good silk reeling process passability, it is more preferable that the hollow ratio is 25% or less by suppressing peeling and splitting during silk reeling. In particular, in dry non-woven fabrics and the like, when a fiber opening process using a card is passed as a pretreatment for forming a sheet, a large impact is transmitted to the fibers, and peeling and division are likely to proceed, leading to a decrease in process passability. Therefore, the hollow ratio is more preferably 20% or less from the viewpoint of suppressing peeling and splitting and maintaining good process passability. In addition, FIG. 2 shows an example of the cross section of the split type composite fiber of the present invention having a hollow portion.

The single yarn fineness of the split type composite fiber of the present invention is not particularly limited, but when it is used for a filter or the like that requires high collection performance, the size of the ultrafine fiber after splitting is as small as possible. As a guide, the single yarn fineness of the split type composite fiber is preferably 8.0 dtex or less. Further, the substantially lower limit of the single yarn fineness of the split type composite fiber of the present invention is 0.5 dtex from the viewpoint of ensuring good operability in the spinning process.

In the split type composite fiber of the present invention, the total number of segments b made of the polymer B may be 2 or more, but it is desirable to increase the number of split segments per cross section from the viewpoint of increasing the production efficiency of the ultrafine fibers. The total number of segments b is preferably 4 or more, and more preferably 8 or more. The practical upper limit of the total number of segments b is 300.
The composition of the fibers is an important factor in developing the desired properties of the non-woven fabric, but in the split type composite fiber of the present invention, the number and size of the divided segments b should be within the above range as a guide. By setting appropriately, it is possible to adjust the fiber composition after division.

The cross-sectional shape of the split type composite fiber of the present invention is not limited to a round cross section, and may be a deformed cross section such as triangular, Y-shaped, or flat. By making it a deformed cross section, it gives a different texture from the round cross section when it is made into a non-woven fabric, and by taking a peculiar shape, it leads to exhibiting excellent performance when used in applications such as filters and wipers. The degree of deformation referred to here is obtained as follows. The cross section of the composite fiber is photographed two-dimensionally, and from the image, the diameter of the perfect circle circumscribing the cross section of the composite fiber is defined as the circumscribed circle diameter, and the diameter of the inscribed perfect circle is defined as the inscribed circle diameter. From the circumscribed circle diameter ÷ inscribed circle diameter, the second digit after the decimal point was rounded off, and the value obtained up to the first digit after the decimal point was defined as the degree of deformity. The circumscribed circle referred to here is the part 5 in FIG. 3, and the inscribed circle is the part 7 in FIG. This degree of deformation was measured for 10 randomly selected fibers, and a simple number average value of the measured values in each image was obtained and used as the degree of deformation. If the degree of deformation is 1.0, the shape of the fiber cross section is a perfect circle. The degree of cross-sectional deformation of the split type composite fiber of the present invention is not particularly limited, but the range of the degree of deformation that can be substantially taken is 1.0 to 10.0. Further, even when the split type composite fiber of the present invention has a modified cross section, a hollow portion may be provided in the fiber cross section from the viewpoint of improving the splittability.

The polymer used for the split type composite fiber of the present invention is not particularly limited as long as it is used for producing a general synthetic fiber, and examples thereof include polyester, polyamide, polyolefin, and acrylic. Although the polymers A and B can be arbitrarily combined, it is preferable to select a combination in which the polymers A and B are incompatible with each other in order to promote the peeling division, and polyester and polyamide, polyester and polyolefin, etc. An example is a combination of polyolefin and polyamide.
Examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate and a copolymer thereof.

Examples of the polyamide include nylon 6, nylon 66, nylon 46, nylon 11, nylon 12, and copolymers thereof.

Examples of the polyolefin include polypropylene, polyethylene, polymethylpentene polybutene, and copolymers thereof.

Examples of other polymers include liquid crystal polyesters such as polyphenylene sulfide, polystyrene and polyarylate, polyethylene naphthalate, polyphenylene sulfide, polycarbonate and copolymers thereof.

Further, from the viewpoint of reducing the environmental load at the time of disposal, a biodegradable polymer may be used, for example, polylactic acid, polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, polybutylene succinate carbonate, etc. Examples thereof include polybutylene adipate terephthalate and polyethylene terephthalate succinate or polymers thereof.

The split type composite fiber of the present invention may contain various additives from the viewpoint of imparting functionality. Antibacterial / antibacterial agent, fragrance / deodorant, antioxidant, antistatic agent, antistatic stabilizer, light stabilizer, water repellent, oil repellent, hydrophilic agent, base oil agent, metal particles, etc. As appropriate, a single or a plurality of additives may be selected and contained, and examples of the addition method include a method of kneading in advance into the polymer used for the fiber, a method of adding at the time of spinning, a method of adding by coating by post-processing, and the like. Can be mentioned. Further, to the split type composite fiber of the present invention, a release agent or the like is appropriately added for the purpose of reducing the adhesive force at the interface within a range in which the passability of the silk reeling process can be ensured from the viewpoint of promoting separation and division in the post-treatment. May be good.

An example of a manufacturing method for the split type composite fiber of the present invention is shown. The method for producing the split type composite fiber of the present invention is not limited by the specific examples described.
As a method for producing a split-type composite fiber of the present invention, if conditions such as a desired single yarn fineness and a desired cross-sectional shape in the above range are adopted, a melt spinning method or a solution spinning method such as wet or dry wet is adopted. It is possible to use a general yarn-making method. Among them, the melt spinning method is mentioned as a preferable method from the viewpoint of high productivity and no need for a solvent recovery step. The mouthpiece used for spinning the composite fiber of the present invention by the melt spinning method is not particularly limited as long as it can composite a polymer of two or more components, but a polymer of a plurality of components can be used as a desired segment. From the viewpoint of precisely controlling the number and its size, the composite base described in Japanese Patent Application Laid-Open No. 2011-174215 is preferably used. Since the cross-sectional shape can be formed with high accuracy by using this composite spinneret, it is possible to control the shape, size, arrangement, etc. of each segment in the fiber cross section. Further, in order to obtain a hollow cross-section yarn, it is also preferable to use a spinneret whose final discharge holes are arranged concentrically in a slit shape as illustrated in FIG.

The ratio of the polymer A and the polymer B used when spinning the composite fiber can be selected in the range of 5/95 to 95/5 in the A / B ratio based on the discharge amount (volume). From the viewpoint of reducing the diameter of the ultrafine fibers generated after the division, it can be said that it is preferable to reduce the ratio of the polymer B constituting the fine segment. However, from the viewpoint of long-term stability of the composite cross section, the A / B ratio is preferably 50/50 to 90/10 as a range for manufacturing efficiently and while maintaining stability.

When the split type composite fiber of the present invention is melt-spun, the temperature at which the polymer used exhibits fluidity is set as the spinning temperature, and when the composite fiber is used, it is mainly higher than the two or more types of polymers. The temperature at which the melting point or high-viscosity polymer exhibits fluidity. The temperature at which this fluidity is exhibited varies depending on the molecular weight, but the melting point of the polymer is a guide, and the temperature may be set at a melting point of + 60 ° C. or lower. If it is less than this, the decrease in molecular weight can be suppressed by suppressing the thermal decomposition of the polymer in the spinning head or the spinning pack, which is preferable.

The composite polymer stream flowing through the spinning pack and discharged from the mouthpiece is cooled and solidified, and then taken up by a roller to which an oil agent is applied and a peripheral speed is regulated to obtain composite fibers. The take-up speed may be determined from the discharge amount and the target fiber diameter, but the take-up speed is preferably in the range of 100 to 3000 m / min for stable production.

The split type composite fiber of the present invention may be wound once and then stretched or wound in order to crystallize a part thereof to fix the fiber structure to impart dimensional stability and to make the fiber finer. It is also good to continue stretching. As the drawing conditions, for example, in a drawing machine consisting of a pair or more of rollers, if the fiber is made of a polymer generally capable of melt spinning, the first roller is set to a temperature equal to or higher than the glass transition temperature and lower than the melting point. Due to the peripheral speed ratio of the second roller, which is equivalent to the crystallization temperature, it is possible to stretch the fiber in the axial direction without difficulty, and to heat-set and wind the fiber. Further, in the case of a polymer showing no glass transition, dynamic viscoelasticity measurement (tan δ) of the fiber may be performed, and a temperature equal to or higher than the peak temperature on the high temperature side of the obtained tan δ may be selected as the preheating temperature. Here, from the viewpoint of increasing the stretching ratio, it is also a preferable means to perform this stretching step in multiple stages. Further, from the viewpoint of controlling the splittability of the split-type composite fiber of the present invention, it is also preferable to apply heat setting between stretching and winding.

When a non-woven fabric is manufactured using the split-type composite fiber of the present invention, it can be widely applied to long-fiber non-woven fabrics such as spunbond and melt blow, short-fiber non-woven fabrics which are short-cut and manufactured by dry or wet method. Yes, the method for producing the non-woven fabric is not particularly limited. In the case of producing a direct-spun non-woven fabric such as a long-fiber non-woven fabric, the obtained fiber is placed on a conveyor or the like without winding up in the above-mentioned example of the method for producing a split-type composite fiber of the present invention. It can be applied by directly spinning and making it into a sheet. At this time, the split type composite fiber may be peeled and split at the time of spinning, but if the split type composite fiber is peeled and split during spinning, the fiber diameter may vary widely or the scattered fiber pieces may cause process troubles. Because of its properties, it is preferable to peel and divide it after forming a sheet. Further, in the case of producing a short fiber non-woven fabric, it is also possible to divide the split type composite fiber of the present invention in advance and use it as a mixture of ultrafine fibers and thick fiber, but the ultrafine fibers are non-woven fabrics. May deteriorate the process passability due to adhesion and accumulation on the manufacturing process and equipment. Therefore, from the viewpoint of ensuring the passability of the non-woven fabric in the manufacturing process, it is preferable that the split-type composite fiber of the present invention is made into a sheet in a composite state and then split. In the production of the short fiber non-woven fabric, it is also preferable to impart crimping to the split type composite fiber of the present invention by a crimper or the like in order to make the sheet a bulkier structure for the purpose of retaining dust and the like. is there. Since the manufacturing process of the non-woven fabric or the like often includes a heat treatment step for the purpose of drying the sheet, setting the heat, etc., it is possible to continuously manufacture the ultrafine fiber sheet by dividing using the difference in heat shrinkage. In addition, stress may be applied to the split interface by other methods, such as high-pressure water flow by the water jet process and impact force by ultrasonic waves. These processes may be performed individually or in combination. It is also possible to do.
Of course, the split-type composite fiber of the present invention can be split by weight loss treatment with a solvent or the like or by utilizing the difference in solvent swelling of the polymer, but from the viewpoint of omitting the manufacturing process and promoting cost reduction, heat It can be said that the method of utilizing the shrinkage difference or the physical impact is preferable.

When a non-woven fabric is produced using the split-type composite fiber of the present invention, it is possible to use only the split-type composite fiber, but for example, in order to satisfy the required properties such as strength retention and bulkiness, the synthetic fiber is used. Not limited to this, different kinds of fibers including natural fibers and inorganic fibers may be appropriately mixed. It is also possible to laminate a plurality of non-woven fabrics containing the split-type composite fibers of the present invention, or to appropriately select and combine and laminate other sheet materials such as non-woven fabrics made of different fibers, woven fabrics, and films.

Since the split-type composite fiber of the present invention suppresses peeling during the silk-reeling process and generates ultrafine fibers after division in the post-process, it is possible to obtain a sheet material having various functions added by the ultrafine fibers with high production efficiency. it can. Suitable for constructing high-textured clothing and non-woven fabric materials with functionality, filter media for air purifiers, air conditioners, building air conditioners, industrial clean rooms, and passenger compartments such as automobiles and trains. It can be suitably used for applications such as surgical masks, face masks, dust masks, medical materials, sanitary materials, wipers, battery separators, artificial leathers, interior materials, and other industrial materials.

Hereinafter, the split type composite fiber of the present invention will be specifically described with reference to Examples.
The following evaluations were carried out for Examples and Comparative Examples.

A. Melt Viscosity of Polymer The chip-shaped polymer was vacuum-dried to a moisture content of 200 ppm or less, and the strain rate was changed stepwise by Capillograph 1B manufactured by Toyo Seiki Co., Ltd. to measure the melt viscosity. The measurement temperature is the same as the spinning temperature, and the melt viscosity of ^{1216s -1 is described in Examples or Comparative Examples.} By the way, it took 5 minutes from the time when the sample was put into the heating furnace to the start of the measurement, and the measurement was performed in a nitrogen atmosphere.

B. Single yarn fineness The weight of 100 m of the produced split type composite fiber was measured, and the fineness was calculated by multiplying by 100. This was repeated 10 times, and the value obtained by rounding off the second decimal place of the simple average value was taken as the fineness of the fiber. The single yarn fineness was calculated by dividing the above-mentioned fineness by the number of filaments constituting the fiber. In this case as well, the value obtained by rounding off the second decimal place was taken as the single yarn fineness.

C. Fiber cross-section The fibers were cut perpendicular to the longitudinal direction, and the fiber cross-section was photographed with a scanning electron microscope SU-1510 manufactured by Hitachi High-Technologies Corporation. From this cross-sectional image, the cross-sectional areas of segments a and b in the fiber cross-section were calculated by the image analysis software Winroof. This was performed for 10 fibers, and the value obtained by rounding off the second decimal place of the average value was taken as the fiber cross-sectional area. The average area of the segment b was obtained by dividing the total area of the segment b in the fiber cross section by the number of segments b and rounding off to the second decimal place.

D. Fibers were cut in the direction perpendicular to the fiber axis with an average major axis razor of segment b, and the cut surface was photographed with a scanning electron microscope SU-1510 manufactured by Hitachi High-Technologies Corporation. From this cross-sectional image, the distance of the longest straight line among the straight lines connecting the contours of the segments b in the fiber cross section was measured by the image analysis software Winrow and used as the major axis. This was performed for 10 fibers, and the value obtained by rounding off the second decimal place of the average value was taken as the segment average major axis of the fibers.

E. Fibers were cut in the direction perpendicular to the fiber axis with a hollow ratio razor, and the cut surface was photographed with a scanning electron microscope SU-1510 manufactured by Hitachi High-Technologies Corporation. From this cross-sectional image, the outer diameter and inner diameter (diameter of the hollow portion) of the fiber cross section were measured by the image analysis software Winroof, and the apparent cross-sectional area of the fiber and the cross-sectional area of the hollow portion were calculated. The hollow ratio of the short fibers was calculated by the following formula as the ratio of the cross-sectional area of the hollow portion to the apparent cross-sectional area of the fibers.
Hollow ratio (%) = (cross-sectional area of hollow part) / (cross-sectional area of fiber (including hollow part)) × 100
This was obtained for 10 randomly selected fibers, and the value obtained by rounding off the first decimal place of the average to an integer was defined as the hollow ratio.

F. Degree of Cross-sectional Deformity The split-type composite fiber of the present invention was cut in the direction perpendicular to the fiber axis with a sword, and the cut surface was photographed with a scanning electron microscope SU-1510 manufactured by Hitachi High-Technologies Corporation. From this image, the diameter of the perfect circle circumscribing the cut surface was defined as the diameter of the circumscribed circle, and the diameter of the inscribed perfect circle was defined as the diameter of the inscribed circle.
Deformity = (circumscribed circle diameter of fiber cross section) / (inscribed circle diameter of fiber cross section)
This was obtained for 10 randomly selected lines, and the average value obtained by rounding off the second digit after the decimal point to the first digit after the decimal point was defined as the degree of variantness.

G. Passability in the processing process As a pre-processing for producing a toe for short cutting using the split type composite fiber of the present invention, a bobbin was rewound and the passability in the processing process was evaluated. The evaluation was made in the following four stages. In the processing method, the split type composite fiber was unwound from the wound yarn and rewound to the bobbin installed on the spindle at a processing speed of 600 m / min via an unheated roller. The fluff of the raw yarn used for the evaluation was counted based on the image taken with an optical microscope.
⊚: No fluff was observed and the process passability was excellent. ○: Slight fluff was observed, but the process process passability was good. Δ: Multiple fluffs were confirmed. , It had sufficient passability in the processing process for practical use. ×: The generation of fluff was remarkable and it was not practical.

H. Split ratio of split-type composite fibers in non-woven fabric The non-woven fabric produced by the methods described in each Example and Comparative Example was densely inserted and filled in a polyurethane tube, and the non-woven fabric was cut perpendicular to the longitudinal direction of the tube. This cut surface was observed with a scanning electron microscope SU-1510 manufactured by Hitachi High-Technologies Corporation, and any 30 fibers derived from segment A were selected from the image obtained by taking a cross-sectional photograph, and the division ratio was calculated by the following formula. Was calculated.
Divided ratio (%) = S _a / S _ab x 100
S _ab: Total surface slit groove and the segment b undivided portion of the segment a in the nonwoven fabric S _a: the number of surface slit grooves of the segments a derived fibers in the nonwoven fabric.

I. Tactile sensation of non-woven fabric With respect to the non-woven fabric produced by using the split type composite fiber, the tactile sensation when the surface of the non-woven fabric was touched by hand was evaluated in the following four stages.
⊚: Has excellent tactile sensation derived from ultrafine fibers ○: Has good tactile sensation derived from ultrafine fibers Δ: Can feel flexibility derived from ultrafine fibers ×: Flexibility derived from ultrafine fibers Poor sex.

Example 1
Using the technique of the composite base described in Japanese Patent Application Laid-Open No. 2011-174215, a large fan shape (segment b2) in which the segment b made of the polymer B is one large fan shape and 16 fine fan shapes are formed around the segment a made of the polymer A. Using a base designed and manufactured to form, polybutylene terephthalate (PBT) resin (melt viscosity 130 Pa · s) is used as polymer A, and polypropylene (PP) resin (melt viscosity 70 Pa · s) is used as polymer B. The composite ratio was A / B = 80/20, and melt spinning was performed at a spinning temperature of 270 ° C. and a spinning speed of 1200 m / min. As a result, unstretched fibers of 250 dtex-72 filaments (total discharge amount 30.0 g / min) were collected, and then the stretching speed was set to 600 m / min between the rollers heated to 50 ° C. and 90 ° C., and 2.05 times stretching was performed. went.

The obtained Kaijima composite fiber was 125 dtex-72 filament, and the single yarn fineness was 1.7 dtex. The segment a in the cross section perpendicular to the fiber axis of the split type composite fiber of Example 1 forms one continuous region, and the segment b has ^{one segment b2 having an area of 6.8 μm 2} and an area of 1. It had 16 7 μm ² segments (average area of segment b: 1.7 μm ² ). The average major axis of the segment b was 1.6 μm. When the split type composite fiber was rewound to the bobbin installed on the spindle at a processing speed of 600 m / min via an unheated roller, there was no problem in the processing process such as fluffing and thread breakage, and the processing process passability was achieved. (Processing process passability: ◎).
After short-cutting the obtained split-type composite fiber to a fiber length of 5 mm, a heat-sealing composite core-sheath composite fiber having a fiber length of 5 mm (core component: PET, sheath component: terephthalic acid 60 mol%, isophthalic acid 40 mol%, ethylene A polyester having a melting point of 110 ° C. (copolymerized polyester 1) copolymerized at a ratio of 85 mol% of glycol and 15 mol% of diethylene glycol is mixed at a ratio of 80/20 (divided composite fiber / core-sheath composite fiber) by weight and wet. After making a non-woven fabric so that the basis weight was 45 g / m ² by paper making, heat treatment was performed at 160 ° C. for 15 minutes in a roll-type dryer. Next, as a water jet process, the obtained non-woven fabric was placed on a 90-mesh net, placed on a conveyor of a water flow injection processing device, and pressure was applied from nozzles arranged in a straight line with a hole diameter of 0.08 mm and a pitch of 0.6 mm. A water stream was ejected once on each side at a feed rate of 10 m / min at 100 kg / cm ^2. The treated non-woven fabric was dried with hot air at 110 ° C. The split ratio of the split type composite fibers in the non-woven fabric after the water jet processing was 83%, which was excellent in splittability. Further, the non-woven fabric had an excellent tactile sensation derived from ultrafine fibers (tactile sensation evaluation: ⊚). The results are shown in Table 1.

Example 2 and Reference Example 3
It was carried out according to Example 1 except that the composite ratio (volume) of Polymer A and Polymer B was changed to 90/10 (Example 2) and 50/50 (Reference Example 3).
The split type composite fiber obtained in Example 2 has a single yarn fineness of 1.7 dtex, an average area of ^{segment b of 0.85 μm 2} , an area of b2 of ^{segment b of 3.4 μm 2} , and a segment b. The average major axis was 1.0 μm. This split-type composite fiber had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in process passability (processing process passability: ⊚). In addition, the split ratio of the non-woven fabric was 80%, which was excellent in splittability, and it had an excellent tactile sensation derived from ultrafine fibers (tactile sensation evaluation: ⊚).

The split type composite fiber obtained in Reference Example 3 has a single yarn fineness of 1.7 dtex, an average area of segment b of 4.3 μm ² , an area of b2 of ^{segment b of 17.0 μm 2} , and a segment b. The average major axis was 2.0 μm. Although slight fluffing was observed in this split-type composite fiber during the rewinding process, the process passability was good (process passability: ◯). In addition, the split ratio of the non-woven fabric was 86%, which was excellent in splittability, and the flexibility derived from the ultrafine fibers had a good tactile sensation (tactile sensation evaluation: ◯). The results are shown in Table 1.

Reference example 4
This was carried out according to Reference Example 3 except that the total discharge rate was changed to 53.0 g / min and melt spinning was performed. The resulting splittable conjugate fiber is a single yarn fineness of 3.0 dtex, the average area of the segment b is 7.5 [mu] m ^2, the area of b2 of segment b is 30.0 ^2, the average major axis of the segment b 2 It was 0.7 μm. Although fluffing was observed in this split-type composite fiber during the rewinding process, the process passability was practically acceptable (process passability: Δ). In addition, the split ratio of the non-woven fabric was 90%, which was excellent in splittability, and had a tactile sensation in which the flexibility derived from the ultrafine fibers could be felt (tactile sensation evaluation: Δ). The results are shown in Table 1.

Reference example 5
This was carried out according to Example 1 except that the base used for spinning was changed and the polymer B was changed to a hole arrangement for dividing the polymer B into 66 segments. The single yarn fineness of the obtained split type composite fiber was 1.7 dtex, the shape of each segment b was flat, the average area was 0.5 μm ² , and the average major axis of the segment b was 1.7 μm. The obtained composite fiber was excellent in rewinding process passability (processing process passability: ⊚). In addition, the split ratio of the non-woven fabric was 60%, which was sufficient for practical use, and had a tactile sensation in which the flexibility derived from the ultrafine fibers could be felt (tactile sensation evaluation: Δ). The results are shown in Table 1.

Comparative Example 1
This was carried out according to Example 1 except that the mouthpiece used for spinning was changed and the hole arrangement was changed so that the segment b2 made of the polymer B had a flat shape and crossed the fiber cross section. The obtained split-type composite fiber had a single yarn fineness of 1.7 dtex, and as shown in FIG. 5, the segment b2 had a flat shape and crossed the fiber cross section, and the segment a was a divided cross section. The average area of the segment b is 1.7 [mu] m ^2, the area of the segment b2 flat shape 6.8 [mu] m ^2, average length of the segment b was 2.4 [mu] m. The obtained composite fiber was peeled and divided during the rewinding process, and the process passability was insufficient (processing process passability: ×). Therefore, the obtained fiber has a lot of fluff and is of a quality that cannot be put into practical use, and cannot be normally made into a non-woven fabric. The results are shown in Table 1.

Comparative Example 2
According to Example 1, except that the base used for spinning was changed, the polymer B was changed to a hole arrangement for dividing the polymer B into eight segments, and the composite ratio in the volume of the polymer A / polymer B was changed to 60/40. Carried out. The obtained split-type composite fiber had a single yarn fineness of 1.7 dtex, the shape of the segment b was fan-shaped, the average area was 8.5 μm ² , and the average major axis of the segment b was 4.7 μm. The fiber was peeled and divided in the middle of the rewinding process, and the process passability was insufficient (processing process passability: ×). Therefore, the obtained fiber has a lot of fluff and is of a quality that cannot be put into practical use, and cannot be normally made into a non-woven fabric. The results are shown in Table 1.

Examples 6-8
Implementation except that the hole arrangement of the base used for spinning was changed so that the average major axis of the segment b was 3.2 μm (Example 6), 4.4 μm (Example 7), and 5.8 μm (Example 8). It was carried out according to Example 1. Average area of the even segment b in any of the embodiments 1.7 [mu] m ^2, the area of the b2 of the segment b was 6.8 [mu] m ^2.

The split-type composite fiber obtained in Example 6 had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in process passability (processing process passability: ⊚). In addition, the fibrability of the non-woven fabric was as high as 83%, and it had a tactile sensation with excellent flexibility derived from ultrafine fibers (tactile sensation evaluation: ⊚).

The split-type composite fiber obtained in Example 7 had good passability in the processing process, although slight fluff was observed in the rewinding process (process passability: ◯). In addition, the fibrability of the non-woven fabric was 86%, which was excellent in splittability, and had an excellent tactile sensation derived from ultrafine fibers (tactile sensation evaluation: ⊚).

Although fluff was observed in the rewinding process of the split composite fiber obtained in Example 8, the process passability was practically acceptable (process passability: Δ). Further, the fibrability of the non-woven fabric was 93%, which was excellent in splittability, and the flexibility derived from the ultrafine fibers had a good tactile sensation (tactile sensation evaluation: ◯). The results are shown in Table 2.

Examples 9 to 10, Reference Example 11
In the mouthpiece used for spinning, the discharge hole arrangement of the polymer B is changed to multiply the area of the segment b2 in the segment b and the average area of the segment b by 3.0 times (Example 9) and 2.5 times (Example 9). 10), except that it was changed to be 2.0 times (Reference Example 11), it was carried out according to Example 1.

The split-type composite fiber obtained in Example 9 has a single yarn fineness of 1.7 dtex, an average area of ^{segment b of 1.8 μm 2} , an area of b2 of ^{segment b of 5.4 μm 2} , and a segment b. The average major axis was 1.6 μm. This split-type composite fiber had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in the process passability (processing process passability: ⊚). In addition, the split ratio of the non-woven fabric was 80%, which was an excellent split property, and the non-woven fabric had an excellent tactile sensation derived from ultrafine fibers (tactile sensation evaluation: ⊚).

The split-type composite fiber obtained in Example 10 has a single yarn fineness of 1.7 dtex, an average area of segment B of 1.8 μm ² , an area of b2 of ^{segment b of 4.6 μm 2} , and a segment b. The average major axis was 1.6 μm. This split-type composite fiber had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in the process passability (processing process passability: ⊚). In addition, the split ratio of the non-woven fabric was 71%, which was a good split property, and the flexibility derived from the ultrafine fibers had a good tactile sensation (tactile sensation evaluation: ◯).

The splittable conjugate fiber obtained in Reference Example 11, the single yarn fineness is 1.7 dtex, the average area of the segment b is 1.9 .mu.m ^2, the area of b2 of segment b is 3.8 .mu.m ^2, segment b The average major axis was 1.6 μm. This split-type composite fiber had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in the process passability (processing process passability: ⊚). In addition, the split ratio of the non-woven fabric was 62%, which was sufficient for practical use, and had a tactile sensation in which the flexibility derived from the ultrafine fibers could be felt (tactile sensation evaluation: Δ). The results are shown in Table 2.

Example 12
The final discharge hole of the base used for spinning was changed to one in which four slit holes were arranged concentrically, and the cross section was changed to have a hollow portion, and the procedure was carried out according to Example 1. The obtained split-type composite fiber has a hollow cross section having a single yarn fineness of 1.5 dtex and a hollow ratio of 5%, the average area of ^{the segment b is 1.5 μm 2} , and the area of b2 of the segments b. Was 6.0 μm ² , and the average major axis of the segment b was 1.6 μm. This split-type composite fiber had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in the process passability (processing process passability: ⊚). In addition, the non-woven fabric had a split ratio of 85%, which was excellent in splittability, and had a tactile sensation derived from ultrafine fibers and had excellent flexibility (tactile sensation evaluation: ⊚). The evaluation results are shown in Table 3.

Examples 13-17
Discharge and cooling conditions so that the hollow ratio is 10% (Example 13), 15% (Example 14), 20% (Example 15), 25% (Example 16), 30% (Example 17). Was changed, but it was carried out according to Example 12.
The split type composite fiber obtained in Example 13 has a single yarn fineness of 1.4 dtex, a hollow cross section having a hollow ratio of 10%, an average area of segment b of 1.4 μm ² , and segment b. Of these, the area of b2 was 5.6 ^{μm 2} , and the average major axis of segment b was 1.6 μm. This split-type composite fiber had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in the process passability (processing process passability: ⊚). In addition, the non-woven fabric had a split ratio of 91%, which was excellent in splittability, and had a tactile sensation derived from ultrafine fibers and had excellent flexibility (tactile sensation evaluation: ⊚).
The split type composite fiber obtained in Example 14 has a single yarn fineness of 1.3 dtex, a hollow cross section having a hollow ratio of 15%, an average area of segment b of 1.3 μm ² , and segment b. Of these, the maximum area of b2 was 5.2 μm ² , and the average major axis of segment b was 1.6 μm. This split-type composite fiber had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in the process passability (processing process passability: ⊚). In addition, the non-woven fabric had a split ratio of 95%, which was excellent in splittability, and had a tactile sensation derived from ultrafine fibers and had excellent flexibility (tactile sensation evaluation: ⊚).
The split type composite fiber obtained in Example 15 has a single yarn fineness of 1.2 dtex, a hollow cross section having a hollow ratio of 20%, an average area of segment b of 1.2 μm ² , and segment b. Of these, the maximum area of b2 was 4.8 ^{μm 2} , and the average major axis of segment b was 1.6 μm. This split-type composite fiber had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in the process passability (processing process passability: ⊚). In addition, the non-woven fabric had a split ratio of 96%, which was excellent in splittability, and had a tactile sensation derived from ultrafine fibers and had excellent flexibility (tactile sensation evaluation: ⊚).
The split type composite fiber obtained in Example 16 has a single yarn fineness of 1.2 dtex, a hollow cross section having a hollow ratio of 25%, an average area of segment b of 1.2 μm ² , and segment b. Of these, the area of b2 was 4.8 ^{μm 2} , and the average major axis of segment b was 1.6 μm. Although slight fluff was observed in the rewinding process, the split-type composite fiber had good passability in the process (process passability: ◯). In addition, the non-woven fabric had a split ratio of 97%, which was excellent in splittability, and had a tactile sensation derived from ultrafine fibers and had excellent flexibility (tactile sensation evaluation: ⊚).
The split type composite fiber obtained in Example 17 has a single yarn fineness of 1.1 dtex, a hollow cross section having a hollow ratio of 30%, an average area of segment b of 1.1 μm ² , and segment b. Of these, the area of b2 was 4.4 ^{μm 2} , and the average major axis of segment b was 1.6 μm. Although fluff was observed in the rewinding process of this split-type composite fiber, the process passability was practically acceptable (process passability: Δ). In addition, the non-woven fabric had a split ratio of 97%, which was excellent in splittability, and had a tactile sensation derived from ultrafine fibers and had excellent flexibility (tactile sensation evaluation: ⊚). The results are shown in Table 3.

Reference Examples 18-19 , Examples 20-21
By changing the hole arrangement of the base used for spinning, the number of segments b is changed to 2 ( Reference Example 18), 4 ( Reference Example 19), 8 (Example 20), 33 (Example 21), 300 (Example 22). ), Except for the change to Example 1.

The splittable conjugate fiber obtained in Reference Example 18, the single yarn fineness is 1.7 dtex, the average area of the segment b is 6.8 [mu] m ^2, the area of the b2 of the segment b is 27.2Myuemu ^2, segment b The average major axis was 2.6 μm. Although fluff was observed in the rewinding process of this split-type composite fiber, the process passability was practically acceptable (process passability: Δ). In addition, the split ratio of the non-woven fabric was 95%, which was excellent in splittability, and had a tactile sensation in which the flexibility derived from the ultrafine fibers could be felt (tactile sensation evaluation: Δ).

The splittable conjugate fiber obtained in Reference Example 19, the single yarn fineness is 1.7 dtex, the average area of the segment b is 4.9 [mu] m ^2, the area of the b2 of the segment b is 19.4Myuemu ^2, segment b The average major axis was 2.3 μm. Although slight fluff was observed in the rewinding process of this split-type composite fiber, the process passability was good (process passability: ◯). In addition, the split ratio of the non-woven fabric was 93%, which was excellent in splittability, and had a tactile sensation in which the flexibility derived from the ultrafine fibers could be felt (tactile sensation evaluation: Δ).

The split type composite fiber obtained in Example 20 has a single yarn fineness of 1.7 dtex, an average area of ^{segment b is 3.1 μm 2} , an area of b2 of ^{segment b is 12.4 μm 2} , and segment b. The average major axis was 1.6 μm. Although slight fluff was observed in the rewinding process of this split-type composite fiber, the process passability was good (process passability: ◯). In addition, the split ratio of the non-woven fabric was 90%, which was excellent in splittability, and the flexibility derived from the ultrafine fibers had a good tactile sensation (tactile sensation evaluation: ◯).

Splittable conjugate fiber obtained in Example 21, a single yarn fineness is 1.7 dtex, the average area of the segment b is the area of the b2 of 0.9 .mu.m ^2, segment b 3.8 .mu.m ² ,, segment b The average major axis was 1.2 μm. This split-type composite fiber had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in the process passability (processing process passability: ⊚). In addition, the split ratio of the non-woven fabric was 84%, which was excellent in splittability, and had a tactile sensation with excellent flexibility derived from ultrafine fibers (tactile sensation evaluation: ⊚). The results are shown in Table 4.

Example 22
According to Reference Example 4, except that the hole arrangement of the base used for spinning was changed, the number of segments b was changed to 300, and the area of segment b2 was 16.0 times the average area of segment b. Carried out. The obtained split-type composite fiber has a single yarn fineness of 3.0 dtex, the average area of ^{segment b is 0.2 μm 2} , the area of b2 of ^{segment b is 3.0 μm 2} , and the average major axis of segment b is 1. It was 0.0 μm. This split-type composite fiber had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in the process passability (processing process passability: ⊚). In addition, the split ratio of the non-woven fabric was 81%, which was excellent in splittability, and had a tactile sensation with excellent flexibility derived from ultrafine fibers (tactile sensation evaluation: ⊚). The results are shown in Table 4.

Examples 23-25
This was carried out according to Example 1 except that the shape of the final discharge hole of the base used for spinning was changed to a triangular shape (Example 23), a flat shape (Example 24), and a Y shape (Example 25).
The split type composite fiber obtained in Example 23 had a single yarn fineness of 1.7 dtex, and the fiber cross section was a triangle having a degree of deformation of 2.0. The average area of the segment b is 1.7 [mu] m ^2, the area of the b2 of the segment b is 6.8 [mu] m ^2, average length of the segment b was 2.1 .mu.m. This split-type composite fiber had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in the process passability (processing process passability: ⊚). In addition, the non-woven fabric had a split ratio of 87%, which was excellent in splittability, and had a tactile sensation derived from ultrafine fibers and had excellent flexibility (tactile sensation evaluation: ⊚).
The split-type composite fiber obtained in Example 24 had a single yarn fineness of 1.7 dtex, and the fiber cross section had a flat shape with a degree of deformation of 5.5. The average area of the segment b is 1.7 [mu] m ^2, the maximum area of the b2 of the segment b is 6.8 [mu] m ^2, average length of the segment b was 2.6 [mu] m. This split-type composite fiber had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in the process passability (processing process passability: ⊚). In addition, the non-woven fabric had a split ratio of 82%, which was excellent in splittability, and had a tactile sensation derived from ultrafine fibers and had excellent flexibility (tactile sensation evaluation: ⊚).
The split-type composite fiber obtained in Example 25 had a single yarn fineness of 1.7 dtex, and the fiber cross section had a Y shape with a degree of deformation of 3.1. The average area of the segment b is 1.7 [mu] m ^2, the maximum area of the b2 of the segment b is 6.8 [mu] m ^2, average length of the segment b was 2.8 .mu.m. This split-type composite fiber had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in the process passability (processing process passability: ⊚). In addition, the non-woven fabric had a split ratio of 90%, which was excellent in splittability, and had a tactile sensation derived from ultrafine fibers and had excellent flexibility (tactile sensation evaluation: ⊚). The results are shown in Table 5.

Example 26
It was carried out according to Example 1 except that the polymer of component A was changed to polyethylene terephthalate (melt viscosity 150 Pa · s), the polymer of component B was changed to nylon 6 (melt viscosity 115 Pa · s), and the spinning temperature was changed to 280 ° C. did. The resulting splittable conjugate fiber, the single yarn fineness is 1.7 dtex, the average area of the segment b is 1.7 [mu] m ^2, the area of b2 of segment b 6.8 [mu] m ^2, the average major axis of the segment b 1 It was 0.6 μm. This split-type composite fiber had no problems such as fluffing and thread breakage during the rewinding process, and was excellent in process passability (processing process passability: ⊚). In addition, the split ratio of the non-woven fabric was 80%, which was excellent in splittability, and had a tactile sensation derived from ultrafine fibers and having excellent flexibility (tactile sensation evaluation: ⊚). The results are shown in Table 5.

Example 27
It was carried out according to Example 1 except that the polymer of component A was changed to nylon 6 (melt viscosity 160 Pa · s), the polymer of component B was changed to polylactic acid (melt viscosity 90 Pa · s), and the spinning temperature was changed to 260 ° C. did. The resulting splittable conjugate fiber, the single yarn fineness is 1.7 dtex, the average area of the segment b is 1.7 [mu] m ^2, the area of the b2 of the segment b has an average major axis of 6.8 [mu] m ^2, segment b is 1 It was 0.6 μm. This split-type composite fiber had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in the process passability (processing process passability: ⊚). In addition, the split ratio of the non-woven fabric was 83%, which was excellent in splittability, and had a tactile sensation with excellent flexibility derived from ultrafine fibers (tactile sensation evaluation: ⊚). The results are shown in Table 5.

Example 28
The procedure was carried out according to Example 1 except that the polymer of the component A was changed to nylon 6 (melt viscosity 160 Pa · s), the component B was changed to polypropylene (melt viscosity 82 Pa · s), and the spinning temperature was changed to 260 ° C. The resulting splittable conjugate fiber, the single yarn fineness is 1.7 dtex, the average area of the segment b is 1.7 [mu] m ^2, the area of the b2 of the segment b has an average major axis of 6.8 [mu] m ^2, segment b is 1 It was 0.6 μm. This split-type composite fiber had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in the process passability (processing process passability: ⊚). In addition, the split ratio of the non-woven fabric was 87%, which was excellent in splittability, and had a tactile sensation with excellent flexibility derived from ultrafine fibers (tactile sensation evaluation: ⊚). The results are shown in Table 5.

Example 29
The procedure was carried out according to Example 1 except that the polymer of the component A was changed to PET (melt viscosity 135 Pa · s), the component B was changed to polypropylene (melt viscosity 91 Pa · s), and the spinning temperature was changed to 290 ° C. The resulting splittable conjugate fiber, the single yarn fineness is 1.7 dtex, the average area of the segment b is 1.7 [mu] m ^2, the area of the b2 of the segment b is the average major axis of 6.8 [mu] m ² ,, segment b It was 1.6 μm. This split-type composite fiber had no problem of fluffing, thread breakage, etc. during the rewinding process, and was excellent in the process passability (processing process passability: ⊚). In addition, the split ratio of the non-woven fabric was 81%, which was excellent in splittability, and had a tactile sensation with excellent flexibility derived from ultrafine fibers (tactile sensation evaluation: ⊚). The results are shown in Table 5.

Example 30
Using the same base and polymers A and B as in Example 1, the composite ratio by volume is A / B = 80/20, melt spinning is performed at a spinning temperature of 270 ° C., and then the spinning speed is 2500 m / min by an ejector. It was spun and collected in the form of a web on a moving net conveyor. The split-type composite fibers constituting this web-like non-woven fabric were not peeled and split, had excellent process passability, and had a single yarn fineness of 1.6 dtex. The average area of the segment b is 1.7 [mu] m ^2, the maximum area of the b2 of the segment b is 6.8 [mu] m ^2, average length of the segment b was 1.6 [mu] m. The basis weight of the obtained web was 45 g / m ² . When the split-type composite fiber was extracted from the web and rewound, there was no problem with fluffing or thread breakage during the process, and the processability was excellent (processing process passability: ◎). The non-woven fabric is heat-treated at 160 ° C. for 15 minutes in a roll-type dryer, and as water jet processing, the non-woven fabric after the heat treatment is placed on a 90-mesh net and placed on the conveyor of the water flow injection processing device, and the pore diameter is 0.08 mm. Water streams were ejected once on each side at a feed rate of 10 m / min at ^{a pressure of 100 kg / cm 2} from nozzles arranged in a straight line with a pitch of 0.6 mm. The treated non-woven fabric was dried with hot air at 110 ° C.

The split ratio of the finally obtained non-woven fabric was 86%, which was excellent in splittability, and had an excellent tactile sensation derived from ultrafine fibers (tactile sensation evaluation: ⊚). The results are shown in Table 5.

Since the split-type composite fiber of the present invention can be easily peeled and split by physical impact, heat treatment, etc. to generate ultrafine fibers and high-fineness fibers, a non-woven fabric containing ultrafine fibers can be easily obtained. It is useful as a filter filter medium, surgical mask, face mask and dustproof mask for air purifiers, air conditioners, building air conditioners, industrial clean rooms and passenger compartments such as automobiles and trains used in hospitals and offices.

1 Segment a in the cross section of the split type composite fiber of the present invention
2 Segment b in the cross section of the split type composite fiber of the present invention
3 Segment b2 having an area more than twice the average area of segment b in the cross section of the split type composite fiber of the present invention.
4 Hollow portion in the cross section of the split type composite fiber of the present invention
5 Circumscribed circle in cross section of deformed cross section fiber 6 Cross section of deformed cross section fiber 7 Inscribed circle in cross section of deformed cross section fiber 8 Slit-shaped discharge hole

Claims (3)

In the fiber cross section in the direction perpendicular to the fiber axis, the polymers A and B are both composite fibers in which the polymers A and B are alternately arranged while being exposed on the fiber surface, the polymer A forms one continuous segment a, and the polymers B are plural. A split-type composite fiber comprising the segment b of the above, having an average area of 0.01 to 4.0 μm ² and having a segment b2 having an area of 2.5 times or more the average area of the segment b.
(Segment b2 is one continuous segment without intrusion of segment a.) The split type composite fiber according to claim 1, wherein the average major axis of the segment b is 0.1 to 3.0 μm. A textile product in which the split-type composite fiber according to claim 1 or 2 constitutes at least a part.

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