JP2017133122A - Sea-island type composite fiber for ultra fine fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sea-island type composite fiber capable of providing an ultra fine fiber excellent in fabric compactness even after elution removing a sea component and openability at rational cost.SOLUTION: There is provided a sea-island composite fiber for ultra fine fiber containing easily soluble polymer as a sea component and hardly soluble polymer as an island component and having area ratio of sea: island on a fiber surface of 10:90 to 60:40 and ebullition water shrinkage ratio of 12% or more. There is provided a sea-island composite fiber for ultra fine fiber wherein the island component of the fiber is eccentrically arranged and the island component is not exposed to a fiber surface.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sea-island type composite fiber for ultrafine fibers. More specifically, the present invention relates to a sea-island type composite fiber for ultrafine fibers that can provide an ultrafine fiber that is excellent in fabric density and excellent in spreadability even after elution and removal of sea components.

  Ultrafine fibers (microfibers) having a single fiber diameter of several micrometers are widely used as suede-like fabrics and wiping cloths because they exhibit a delicate and soft feel when made into fabrics. In particular, as a technique for easily producing microfibers, sea-island type composite fibers containing a hardly soluble island component in a sea component made of a readily soluble polymer, or hardly soluble microfibers are easily soluble polymers. The use of partitioned split fiber composite fibers is widely known (see Patent Document 1). These techniques are part of the technology, after winding up as a composite fiber, and then immersing the composite fiber or fabric product in a solubilizer to remove the easily soluble polymer and obtain a hardly soluble microfiber. It is.

  In recent years, ultrafine fibers (nanofibers) having a single fiber diameter of 1 micrometer or less have been proposed in pursuit of a more delicate touch and soft feeling. In addition to the ultimate softening by scaling down the fiber diameter, nanofibers have been suggested to have nanosize-specific effects due to the dramatic increase in specific surface area and porosity of single fiber groups. Therefore, early research, development and stable manufacturing are required.

  As one of the methods for producing nanofibers, a method for producing bundled nanofibers by combining a polymer blend technique and a polymer dissolution and removal technique has been proposed (see Patent Document 2). Although the nanofiber itself manufactured by this proposal is a short fiber, since it forms the aggregate | assembly which consists of a short fiber, it can be set as textile products, such as a textile fabric and a knitted fabric, as a long fiber-like thread. In addition, as a method for obtaining long-fiber nanofibers, the conventional sea-island type composite fiber technology has been developed, and the number of islands in the fiber cross section of one composite fiber is increased to super-islands. Techniques for obtaining fibers and the like have been disclosed. For example, in Patent Document 3, nanofibers with high productivity are obtained by using a copolymer polyester of 5-sodium sulfoisophthalic acid and polyethylene glycol as an easily soluble polymer (sea component) and further defining the island component arrangement in the sea-island type composite fiber. There has been proposed a method of manufacturing. However, in the sea-island type composite fibers exemplified in the prior art represented by these proposals, the ultrafine fibers obtained after elution of sea components are all straight, and the fiber bundles are like bundles of sawmen. Since the openability is poor, it is difficult to obtain the gaps between the ultrafine fibers, causing a decrease in color development and wiping when used as a textile, and functioning as an ultrafine fiber. It was not fully utilized. In addition, since the fibers are thinned by the elution treatment of the sea component, there is a disadvantage that the fabric density is lowered and the shape stability of the fabric is significantly lowered. For the purpose of improving the spreadability, a method of applying false twisting has also been proposed (see Patent Document 4). However, in addition to the increase in manufacturing cost, it is also necessary to compensate for the decrease in fabric density due to sea component elution treatment. The effect was insufficient.

  In view of the above circumstances, there has been a demand for a sea-island type composite fiber that can provide ultrafine fibers with excellent fabric density and excellent spreadability even at a reasonable cost after elution and removal of sea components.

JP 2005-163234 A JP 2004-162244 A JP 2007-100343 A JP 2008-75228 A

  The object of the present invention is to provide a sea-island type composite fiber that can overcome the above-mentioned problems and obtain ultrafine fibers that are excellent in fabric denseness and excellent in openability even after sea components are eluted and removed at a reasonable cost. There is to do.

The above problem is solved by the following means.
(1) A sea-island composite fiber having an easily soluble polymer as a sea component and a hardly soluble polymer as an island component, the sea: island area ratio in the fiber cross section being 10:90 to 60:40, and boiling water shrinkage A sea-island composite fiber for ultrafine fibers, characterized in that the rate is 12% or more.
(2) The sea-island type composite fiber for ultrafine fibers according to (1), wherein the island component is eccentrically arranged to satisfy the following requirements A to D in the fiber cross section.

      A. There is an island missing area where no island component exists on the radius line connecting the fiber center and the outer periphery.

      B. The area around the island lacking area should be covered with island components so that the area is not exposed on the fiber surface.

      C. The angle (A) formed by both ends in the circumferential direction of the island missing area and the fiber center is 60 ° ≦ A ≦ 270 °.

D. The ratio of the thickness (S) in the fiber diameter direction of the island missing area to the fiber diameter (R), S / R, is 0.18 ≦ S / R ≦ 0.45.
(3) The sea-island composite fiber for ultrafine fibers according to (1) or (2), wherein the island component fiber after elution of the sea component has a dry heat shrinkage at 150 ° C. of 18.0% or more.
(4) The ultrafine material as set forth in any one of (1) to (3), which has a latent crimp property in which a crimped coil having a crimp pitch of 10 or less appears in the fiber after dissolution of the sea component. Sea-island composite fiber for textiles.

  ADVANTAGE OF THE INVENTION According to this invention, the sea-island type | mold composite fiber for ultrafine fibers from which the ultrafine fiber which was excellent in the fabric denseness and excellent in the openability after the elution removal of the sea component can be obtained can be obtained at a reasonable cost. Specifically, the present invention provides a sea-island type composite fiber that can self-repair gaps between fabric structures caused by thinning of fibers during the elution treatment of sea components, and can maintain fabric density.

  Furthermore, the fabric obtained from the sea-island type composite fiber of the present invention is characterized by ultrafine fibers as sports clothing and outer materials that have been avoided so far due to the addition of the fineness of the fabric to the lightness of ultrafine fibers. As a new material that makes use of delicate touch and soft feeling, it can be used widely and suitably.

FIG. 1 is an example of a fiber cross section of the sea-island composite fiber for ultrafine fibers of the present invention. FIG. 2 is a fiber cross-section of a sea-island type composite fiber for ultrafine fibers outside the present invention. FIG. 3 is a schematic diagram for explaining a fiber diameter (R) and an island missing area in a fiber cross section of the sea-island composite fiber for ultrafine fibers of the present invention. FIG. 4 is a schematic diagram for explaining the thickness (S) in the fiber diameter direction in the fiber cross section of the sea-island composite fiber for ultrafine fibers of the present invention.

Hereinafter, the present invention will be described in detail together with preferred embodiments.
The sea-island type composite fiber of the present invention is a sea-island type composite fiber having a readily soluble polymer as a sea component and a hardly soluble polymer as an island component. The polymer forming the sea or island is not particularly limited as long as it is incompatible with each other and is a fiber-forming thermoplastic polymer, and examples thereof include polyester, polyamide, polyethylene, and polypropylene. Of these, polyester and polyamide are preferably used. It is done. More specifically, polyesters include, for example, polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, those obtained by copolymerizing a dicarboxylic acid component, a diol component or an oxycarboxylic acid component, or a blend of these polyesters. It is done. Furthermore, aliphatic polyesters such as polylactic acid, polybutylene succinate and polyε-caprolactam known as biodegradable polyesters may be used. Examples of the polyamide include nylon 6, nylon 66, nylon 69, nylon 46, nylon 610, nylon 12, polymetaxylene adipamide, and those obtained by copolymerizing or blending these components. If necessary, inorganic fine particles, organic compounds, and carbon black can be added to the thermoplastic resin as a matting agent such as titanium oxide, a flame retardant, a lubricant, an antioxidant, and a coloring pigment.

  As described above, the sea-island type composite fiber of the present invention comprises a sea component of an easily soluble polymer and an island component of a hardly soluble polymer with respect to a solubilizer. Both polymers are incompatible with each other, and it is important to produce yarns in as large a combination as possible within a range in which there is a difference in dissolution rate during sea removal treatment. As the range of the dissolution rate, it is necessary to select an island component polymer in which the dissolution rate of the sea component is at least 5 times that of the island component or not dissolved in the dissolving agent at all. By making the difference in dissolution rate 5 times or more, dissolution and removal of sea components are performed smoothly, and the difference in contact time of the island component solubilizer at the surface / core portion of the sea island single yarn is reduced, so the island fiber diameter variation is small. A group of nanofiber single yarns can be obtained. A more preferable range of the dissolution rate difference is 20 times or more.

  Examples of combinations of the above polymers are listed below. When the sea component polymer solubilizer is an alkaline aqueous solution, the sea component is combined with a copolymerized polyester resin or an aliphatic polyester resin, and the island component is combined with a homopolyester resin or a polyamide resin, a polyester resin composed of an aromatic dicarboxylic acid, or the like.

  When the dissolving agent is an acid aqueous solution, the sea component is combined with a polyamide resin and the island component is combined with a polyester resin. When the dissolving agent is an organic solvent such as toluene or trichlorethylene, the sea component is combined with a polyolefin resin, and the island component is combined with a polyester resin or a polyamide resin.

  When the dissolving agent is hot water, the sea component is combined with a polyvinyl alcohol resin, and the island component is combined with a polyester resin or a polyamide resin.

  As another example, even when different types of resins such as a polyester-based polymer and a polyamide-based polymer are used, a difference in shrinkage due to a difference in polymer characteristics (difference in molecular orientation) can be generated.

  The polymer used for the island component of the sea-island type composite fiber of the present invention can be polyester, for example, homopolyethylene terephthalate, but is preferably a highly shrinkable polymer. As a polymer used for polyester-based high shrinkage, a copolyester such as isophthalic acid can be suitably used. By dissolving and removing the sea component, the highly shrinkable fiber of the island component becomes an ultrafine single yarn, and this ultrafine highly shrinkable fiber needs to have latent crimpability. By having the latent crimpability, a difference occurs in the yarn length, and a random yarn length is preferable because the fiber-opening property is good. And because it is an ultra-fine fiber made of a highly shrinkable polymer, heat is applied in a high-order process (for example, high-temperature dyeing + high-temperature dry heat bulk-up treatment), the fiber shrinks greatly, the fabric swells, and the sea component dissolves. It is preferable because the thinness of the fabric due to the removal can be compensated and the denseness can be improved.

  In the sea-island type composite fiber of the present invention, after the sea component is dissolved and removed, the high-shrinking fiber of the island component becomes a superfine single yarn, but the reason why it has latent crimping property while being a single component yarn will be described in detail.

  The sea-island type composite fiber of the present invention exhibits excellent fabric density even in a multi-packed shape in which the island components are uniformly arranged in the entire cross section in the fiber cross section. If the components are arranged eccentrically, it is possible to obtain more excellent fabric density and texture.

  That is, in the fiber cross section, it is preferable that there is an island lack area where no island component exists on the radius line connecting the fiber center and the outer periphery. If the periphery of the island defect area is coated with an island component and the island defect area is not exposed on the fiber surface, gradation will occur in the molecular orientation of the island component, and the ultrafine fiber after elution of the sea component will have crimped coils. Present. This is because, due to the existence of the island missing area, the spinning stress distribution applied to the island components around the island missing area and the area away from the island missing area is different, resulting in an island component molecular orientation gradation. Furthermore, it is preferable to arrange the island components in one or two rows on the outer periphery of the island missing area because a difference in the island component molecular orientation gradation is further generated. Furthermore, since the island component arranged in the outer peripheral portion of the island missing area has an effect of suppressing the bending of the yarn discharged from the die, it is preferable from the viewpoint of the homogeneity of the composite fiber.

  In particular, the angle (A) between the circumferential ends of the island notch area and the fiber center is 60 ° ≦ A ≦ 270 °, and the thickness (S) in the fiber diameter direction of the island notch area and the fiber diameter ( When the ratio S / R and the ratio S / R are in the relationship of 0.18 ≦ S / R ≦ 0.45, crimped coils are easily developed efficiently, and the texture can be improved.

  In this crimp coil, if the value (crimp pitch) obtained by dividing the interval (L) between the crest and trough of the crimp by the height (H) of the crest and trough is 10 or less, the ultrafine fiber bundle is a bundle of straight rods. From the above, since it has a rod-like wave-like shape composed of curved portions, light reflection on the fiber surface is suppressed and excellent deep color properties are achieved. More preferably, it is 5 or less. If the angle (A) between the circumferential ends of the island-missing area and the fiber center is 60 ° or more, the molecular orientation gradation of the island component is likely to occur, and if it is 270 ° or less, the island component is reduced with a smaller sea component ratio. Easily form missing areas effectively. More preferably, it is 75 degrees or more and 180 degrees or less, More preferably, it is 90 degrees or more and 120 degrees or less.

  Further, when the relationship between the fiber diameter direction thickness (S) of the island lacking area and the fiber diameter (R) is in the range of 0.18 ≦ S / R ≦ 0.45, the crimped coil is most efficiently used. Can be expressed. More preferably, they are 0.20 or more and 0.40 or less, More preferably, they are 0.23 or more and 0.37 or less.

  As described above, the preferred sea-island type composite fiber of the present invention has a latent crimping performance even though it is a single component by arranging the island component in an eccentric manner. The ultra-fine high-shrinkable fibers develop crimped coils, resulting in random yarn length differences, greatly improving the spreadability and obtaining a fabric with high density.

  Here, it is important that the area ratio of sea: island in the fiber cross section is in the range of 10:90 to 60:40. By setting the sea component to 10% or more, the island components can be prevented from being fused to each other, so that a fabric having excellent sea removal properties and high strength and high quality can be obtained. Further, by setting the sea component to 60% or less, it is possible to suppress the thinning of the fiber that occurs when the sea component is dissolved and removed, and to effectively exhibit the self-healing ability of the fabric denseness. In addition, since product loss due to sea component elution can be reduced, productivity of ultrafine fibers is also increased, which is preferable. More preferably, it is the range of 20: 80-50: 50, More preferably, it is the range of 30: 70-40: 60.

  The number of islands in the sea-island composite fiber single yarn in the sea-island composite fiber of the present invention is preferably in the range of 30 to 200 islands. When the number of islands is 30 or more, the shape stability of the sea-island type composite fiber and the productivity of the ultrafine fiber are increased. Further, by setting the number of islands to 200 islands or less, it is possible to avoid the island component fusion defect, and further, the difference in the contact time of the solubilizer at the surface / core portion of the sea-island type composite fiber monofilament when the sea component is dissolved and removed. By reducing the number of fibers, it is possible to obtain ultra-fine fibers with small fiber diameter variations and high strength. A more preferable range of the number of islands in the sea-island type composite fiber single yarn is 50 to 180 islands, and more preferably 80 to 150 islands.

  The fiber diameter of the sea-island composite fiber of the present invention is preferably 30 to 300 dtex. By setting the fiber diameter to 30 dtex or more, a high-strength and high-quality fabric can be obtained. Moreover, the fine touch and soft feeling of an extra fine fiber are obtained by setting it as 250 dtex. More preferably, it is 40-150 dtex.

  In addition, it is preferable that the fiber diameter after the sea component removal of the island component of the sea-island type composite fiber of the present invention is 100 to 7000 nm. When the fiber diameter is 100 nm or more, fibrillation of the nanofiber single yarn group can be suppressed, which is preferable. On the other hand, it is preferable that the island component diameter is 7000 nm or less because the fabric product has a delicate touch and soft feeling that cannot be achieved with existing synthetic fibers. More preferably, it is 200-5000 nm, Most preferably, it is 300-1000 nm.

  When the boiling water shrinkage of the sea-island type composite fiber is 12% or more, it is important for enhancing the fabric density at the sea component elution stage. More preferably, it is 15% or more and 20% or more. Although there is no particular upper limit, it is 30% or less in consideration of the yarn forming property, the form stability of the fabric, and other physical property values.

  In the sea-island type composite fiber of the present invention, it is preferable that the 150 ° C. dry heat shrinkage ratio of the fiber after elution of sea components is 18% or more. By setting the ratio to 18% or more, it is possible to self-repair the gaps between the fabrics caused by the fiber thinning at the time of sea removal, and it is possible to maintain the denseness of the fabrics at a reasonable cost. More preferably, it is 20% or more, more preferably 25% or more. Although there is no particular upper limit, it is 40% or less in consideration of the yarn-forming properties, the form stability of the fabric, and other physical property values.

Next, a preferred method for producing the sea-island type composite fiber of the present invention will be described.
The composite fiber of the present invention is not limited to the two-step method in which the discharged polymer is once wound as an undrawn yarn and then drawn, and any of the direct spinning drawing method and the high-speed spinning method in which spinning and drawing steps are continuously performed It can also be manufactured in the process. Moreover, since the range of the spinning speed in the high-speed spinning method is not particularly defined, it may be a step of drawing after winding as a semi-drawn yarn. Furthermore, yarn processing such as false twisting can be performed as necessary.

  When the sea-island type composite fiber is produced by a two-step method, any known drawing method can be used in addition to hot roll-hot roll drawing or drawing using a hot pin. Moreover, you may extend | stretch, adding a confounding and false twist according to a use. In order to suppress composite abnormality such as generation of fuzz and peeling of both components, it is preferable to draw the drawn yarn so that the residual elongation is 25 to 50%.

  Heat setting in a stretched state and cooling to below the glass transition temperature while maintaining tension and structurally fixing the molecular chain can increase the shrinkage stress and is effective in improving the fabric texture. Specifically, it is preferable to pass a cold roll in a stretched state of about 0.3 to 3.0% because a high shrinkage stress is obtained.

  The spinning temperature is preferably set at a temperature +20 to + 50 ° C. higher than the polymer melting point. By setting it higher than the polymer melting point by + 20 ° C. or more, it is possible to prevent the polymer from solidifying and clogging in the spinning pipe, and to set the temperature to be higher than + 50 ° C. It is preferable because thermal deterioration can be suppressed.

  A polymer having a difference in dissolution rate of the sea-island component of 5 times or more is selected as the sea component, and weighed so that the sea component area ratio in the sea-island composite fiber is 10 to 60%. The island component is measured and melted and discharged so that the area ratio is 90 to 40%.

  The sea-island type composite fiber of the present invention is preferably obtained by a melt spinning method, but the die may be of any known internal structure, as long as it can be stably spun in quality and operation, Distribution plate type bases exemplified in JP 2011-174215 A, JP 2011-208313 A, and JP 2012-136804 A can be suitably used. At this time, if the spinning draft is 300 times or less, it is preferable to obtain a homogeneous fiber in which variation in physical properties between filaments is suppressed. The number of filaments can be appropriately set depending on the size of the die, but it is preferable to maintain the filament discharge hole interval at 10 mm or more because the filament can be cooled and solidified smoothly and uniform fibers can be easily obtained.

  Here, a method of forming the island missing area will be described. By using the above-described distribution plate type die, the island component of the sea-island composite fiber can be arbitrarily arranged, and the sea component is arranged at the place where the island component is usually arranged in the fiber cross section (the island component is not arranged). ), Form an island-only area by forming an area of sea components only.

The spinning draft represented by the following formula of the sea-island type composite fiber of the present invention is preferably 50 to 300.
Spinning draft = Vs / V0
Vs: Spinning speed (m / min)
V0: discharge linear velocity (m / min)
By setting the spinning draft to 50 or more, it is possible to prevent the polymer flow discharged from the die hole from staying directly under the die for a long time and to suppress the contamination of the die surface. Further, it is preferable to set the spinning draft to 300 or less because it is possible to suppress yarn breakage due to excessive spinning tension, and sea-island composite fibers can be obtained with stable yarn-making properties. More preferably, it is 80-250.

  The spinning tension of the sea-island composite fiber of the present invention is preferably 0.02 to 0.15 cN / dtex. By setting the spinning tension to 0.02 cN / dtex or more, there is no yarn interference between single yarns due to yarn swinging during spinning, and it is possible to achieve stable running because there is no reverse winding on the take-up roller as the first roller. Become. In addition, it is preferable to set the spinning tension to 0.15 cN / dtex or less because a sea-island type composite fiber can be obtained stably. A more preferable range of the spinning tension is 0.07 to 0.1 cN / dtex.

  It is preferable to strictly control the cooling and solidification of the discharged polymer when the sea-island type composite fiber of the present invention is operated and quality is stably produced. When the amount of discharged polymer is reduced as the fineness is reduced, the thinning of the polymer and the cooling and solidification approach the base (move upstream). Therefore, the cooling method assumed in the prior art can only obtain fibers with a lot of yarn in the longitudinal direction. Absent. In addition, the accompanying airflow due to the solidified fibers increases and the spinning tension increases, so a technique for reducing these is required. As a method for reducing the increase in spinning tension, the cooling start point is preferably set to 20 to 120 mm from the die surface. A cooling start point of 20 mm or more is preferable because it can suppress a decrease in the surface temperature of the die due to cooling air and can avoid various problems such as low-temperature yarn, clogging of the die hole, complex abnormality, and ejection spots. Moreover, it is preferable to set the cooling start point to 120 mm or less because a high-quality sea-island type composite fiber with little yarn unevenness in the longitudinal direction can be obtained. A more preferable range of the cooling start point is 25 to 100 mm.

  Moreover, in order to suppress the temperature reduction of the base surface due to the cooling air, a temperature control of the cooling air or a heating device may be installed in the periphery of the base as necessary.

  The distance from the die discharge surface to the oil supply position is preferably 1300 mm or less. By controlling the distance from the nozzle discharge surface to the oil supply position to 1300 mm or less, the width of yarn swaying by cooling air can be suppressed, the yarn unevenness in the longitudinal direction of the fiber can be improved, and the accompanying airflow until the yarn converges can be suppressed. Therefore, it is preferable because the spinning tension can be reduced and stable spinning with less fluff and yarn breakage is easily obtained. A more preferable range of the oil supply position in the spinning process of the sea-island type composite fiber is 1200 mm or less.

  This material is a new product that takes advantage of the delicate touch and softness characteristic of ultrafine fibers as sporting clothing and outer materials that have been avoided so far, due to the addition of lightweight fabric due to ultrafine fibers and the fineness of the fabric. It can be suitably used as a wide range of materials, and is suitable for general clothing as well as outdoor and swimwear sports clothing.

  The sea-island type composite fiber of the present invention will be specifically described below with reference to examples. About the Example and the comparative example, the following evaluation was performed.

(1) Intrinsic viscosity (IV)
Ηr of the definition formula is obtained by dissolving 0.8 g of a sample polymer in 10 mL of O-chlorophenol (OCP) having a purity of 98% or more, and obtaining the relative viscosity ηr by the following formula using an Ostwald viscometer at a temperature of 25 ° C. The intrinsic viscosity (IV) was calculated.

ηr = η / η0 = (t × d) / (t0 × d0)
Intrinsic viscosity (IV) = 0.0242 ηr + 0.2634
η: viscosity of polymer solution η0: viscosity of OCP t: drop time of solution (second)
d: density of the solution (g / cm ³ )
t0: OCP fall time (seconds)
d0: OCP density (g / cm ³ ).

(2) Difference in dissolution rate After preparing and weighing about 2g of each of the polymers used in the sea component polymer and the island component polymer, and weighing them with a 3 wt% sodium hydroxide aqueous solution at 95 ° C for 5 minutes, the following formula is obtained. The difference in dissolution rate was calculated.

Weight loss rate of sea component polymer (%: S) = ((weight before treatment) / (weight after treatment)) × 100
Reduction rate of island component polymer (%: I) = ((weight before treatment) / (weight after treatment)) × 100
Dissolution rate difference = S / I.

(3) High elongation In accordance with JIS L1013 (1999), using TENSILON / UTM-III-100 manufactured by TOYO BALDWIN, the strength (cN / dtex) at the filament breaking point under the measurement conditions of a sample length of 20 cm and a tensile speed of 20 cm / min. ), Elongation (%) was measured.

(4) Fineness of composite fiber 100 pieces of casserole were prepared using a measuring machine having a frame circumference of 1.0 m, and the fineness was measured according to the following formula.

  Fineness (dtex) = 100 weights of casserole (g) × 100

(5) Boiling water shrinkage of sea-island type composite fiber A load of 2.0 g / dtex was applied to the sea-island type composite fiber that was crushed 10 times using a measuring machine with a frame circumference of 1.0 m, and the sample length L1 (mm ). Remove the load and treat with boiling water for 15 minutes. A load of 2.0 g / dtex is again applied to the treated cassette, and the sample length L2 (mm) is measured. The dry heat shrinkage is calculated according to the following formula.

  Boiling water shrinkage rate (%) = ((sample length L1 (mm) −sample length L2 (mm)) / sample length L1 (mm)) × 100.

(6) Dry heat shrinkage rate of island component fibers Sea component using sea hydroxide type 1% aqueous solution at 98 ° C for sea island type composite fiber that has been crushed 10 times using a measuring machine with a frame circumference of 1.0m. Is dissolved and removed to obtain island component fibers (nanofiber single yarn group). A load of 4.0 g / dtex is applied to the resulting island component fiber case, and the sample length A (mm) is measured. Remove the load and treat in a dry heat oven at 150 ° C. for 15 minutes. After the treatment, a load of 4.0 g / dtex is again applied to the fiss of the island component fibers, and the sample length B (mm) is measured. The dry heat shrinkage is calculated according to the following formula.

  Dry heat shrinkage ratio (%) = ((sample length A (mm) −sample length B (mm)) / sample length A (mm)) × 100.

(7) Area composite ratio of sea-island type composite fiber “Reichert-Nissei ultracut N” (ultra microtome) equipped with a diamond knife, embedded in epoxy resin, frozen with Reichert FC-4E cryosectioning system After cutting, an observation image of the cut surface was taken with an H-7100FA transmission electron microscope (TEM) manufactured by Hitachi. From this image, arbitrary 10 fibers were selected, and using the image processing software (WINROOF), the area of the sea-island type composite fiber and the total area of the island components were calculated to obtain the area composite ratio.

(8) Measurement of S / R of Island Missing Area First, an island missing area is defined as an island missing area excluding a minute place between neighboring island components. That is, as shown by the diagonally downward slanting portion in FIG. 3, the polygon formed by connecting the vertices on the island missing area side of the island component existing outside the area is called an island missing area.

  Based on the image used in (7) above, the image processing software (WINROOF) was used to measure the diameters at any three locations of the sea-island composite fiber, and the result was taken as the fiber diameter (R).

  Next, when the point where the length in the fiber diameter direction of the island lacking area is the straight line passing through the center of the island-island composite fiber and the island missing area is defined as the thickness (S) in the fiber diameter direction of the island missing area, the following formula S / R is obtained from

  S / R = (Thickness in the fiber diameter direction of the island lacking area (S)) / (Fiber diameter (R)).

(9) Island missing area angle (A)
As shown in FIG. 4, the angle formed by the straight line connecting the vertices of both ends in the fiber circumferential direction of the island notch area (8) and the fiber center was measured as the angle (A) of the island notch area.

(10) Crimped pitch Sea-island composite fibers crushed to a sample length of 100 mm (loop) are dissolved and removed using a 1% aqueous solution of sodium hydroxide at 98 ° C to remove island components (nanofibers). Single yarn group). The obtained island component fibers were sandwiched between A4 size transparent films, and images were taken at an observation magnification of 500 to 1000 times using a KEYENCE microscope VHX-2000. The length in the fiber axis direction of the ridge and valley L (mm) is measured, the height H (mm) of the ridge and valley (direction perpendicular to the fiber axis) is measured, and the crimp pitch is calculated from the following formula (1) Is calculated. Further, among the arbitrary 20 lines, the maximum crimp pitch is set to the maximum value (−), the minimum crimp pitch is set to the minimum value (−), and the maximum / minimum ratio is obtained by the following equation (2).

Crimp pitch (-) = Valley interval L (mm) / Height H (mm) (1)
Maximum / minimum ratio (−) = maximum value (−) / minimum value (−) (2)

(11) Opening property When the opening property is evaluated in the observation image used in (10) above, the ultrafine fibers are present alone, and the case where the fibers are in a loose state is considered to have good opening property. When the number of bundles per image is less than 3, the spreadability is “「 ”. When the number is less than 6, the spreadability is“ good ”. When the number of bundles is 6 or more, the spreadability is not possible. "

(12) Yarn Stability Stabilization was performed for each example, and the yarn stability of the sea-island type composite fiber was evaluated in three stages from the number of yarn breaks per 10 million meters.
Very good ◎: Less than 0.8 times / 10,000,000 m ◯: 0.8 times / 10,000,000 m or more, 2.0 times / less than 10,000,000 m Defect x: 2.0 times / 10,000,000 m or more

(13) Breathability and denseness Create a Zokki fabric with a warp density of 5280 / m, a weft density of 3580 / m, and a raw machine width of 1.30m, refining at 95 ° C, and using a 3wt% aqueous sodium hydroxide solution Sea components were removed by alkali weight reduction of 95 wt% or more. Furthermore, after drying once at 130 ° C., finish heat setting was performed at 160 ° C. and a width of 110 cm. The fabric thus obtained was measured for air permeability according to JIS L1096 (1999) A method. Based on this, the denseness was evaluated in the following three stages, and a value of ○ or higher was regarded as acceptable.

◎: Less than 1 cc / cm ² · sec ○: 1 to 3 cc / cm ² · sec
X: 3 cc / cm2. Over sec.

(14) Fabric Evaluation The fabric produced in (13) above was dyed with 98 ° C. Terraseal Navy Blue SGL (0.4% owf) as a test fabric, and the fabric was touched by a skilled inspector (5 persons). The texture, density, surface uniformity, and dyeing uniformity were evaluated relative to each other. For each item, the sensory evaluation was performed in four stages: very good (4 points), good (3 points), not very good (2 points), and bad (1 point). Point) was calculated and evaluated as follows by the average value of the total value of each inspector.
Very good ◎: 14 points or better ◯: Less than 14 points, 9 points or more defective ×: Less than 9 points

Example 1
Preparation of copolymerized polyethylene terephthalate with IV = 0.67 obtained by copolymerizing 7.1 mol% and 4.4 mol% of isophthalic acid and bisphenol A ethylene oxide adduct as a hardly soluble island component, respectively, with respect to the total acid component did. As an easily soluble sea component polymer, an alkali easily soluble polyethylene terephthalate having IV = 0.55 containing 7.3 wt% of 5-sodium sulfoisophthalic acid as a copolymerization component was prepared. The difference in dissolution rate between the sea component and the island component in the alkaline aqueous solution was 25 times.

Both the island component polymer and the sea component polymer were melted at 270 ° C. and 280 ° C. using an extruder, respectively, and weighed with a pump. Each polymer has the highest melting point, which is 30 ° C. higher than the melting point of the sea component 290 The spinning temperature was set at 0 ° C., and the temperature was kept flowing into the die. The weight composite ratio of the sea component and the island component was 30/70, and was flown into the sea-island type composite spinneret having 84 islands and 112 discharge holes. Each polymer merged inside the base, formed a composite form in which the island component polymer was included in the sea component polymer, and was discharged from the base. In addition,
A distribution plate type base in which island components are arranged so that the island missing area shown in FIG. 1 is obtained and the island missing area is not exposed outside the island missing area is used.

  The yarn discharged from the base is cooled by an air-cooling device, applied with an oil agent, wound by a winder at a speed of 1500 m / min so that the spinning draft becomes 220, and stably wound as an undrawn yarn of 182 dtex-112 filament. I took it. At this time, the cooling start point is set to 97 mm from the nozzle discharge surface, and the oil supply position is set to 1130 mm from the nozzle discharge surface, so that the spinning stress becomes 0.10 cN / dtex, and the suppression of the longitudinal yarn unevenness and the stability of the yarn forming property are achieved. planned. With respect to the undrawn yarn obtained by this process, no fusion of island components was observed by microscopic observation at an observation magnification of 500 times.

  Subsequently, the obtained undrawn yarn was fed to a drawing device at a speed of 300 m / min, and drawn at a drawing temperature of 90 ° C. and a draw ratio of 2.56 times so that the elongation was about 20 to 40%. Heat setting was performed at 130 ° C., and a drawn yarn of 66 dtex-112 filament having a strength of 2.6 cN / dtex and an elongation of 31% was stably obtained through the spinning and drawing processes.

  Table 1 shows the results of evaluation performed using the obtained sea-island type composite fibers. The sea-island composite fiber had a boiling water shrinkage of 18%, and was a useful yarn as a yarn used for a fabric having high density and excellent spreadability.

  Further, the fiber after elution of the sea component of the island component had a dry heat shrinkage of 29%. The fiber form is bulky, and it is crimped as if some fibers have been false twisted. The minimum value of the crimped pitch is 4, and the openability is good due to random yarn length differences. It is in a state. The fabric obtained from this fiber had a high density and a soft and bulky fabric with a good texture.

Examples 2-9
Examples 2 to 4 are combinations of a hardly soluble component and a readily soluble component, Examples 5 to 8 are the size of the island lacking area, and Example 9 is a composite ratio, except that the composite ratio is changed as shown in Table 1, respectively. A sea-island type composite fiber was obtained in the same manner as in Example 1, and as shown in Table 2, it was possible to obtain a raw yarn useful as a raw yarn for use in a fabric having high density and excellent spreadability.

Comparative Examples 1-3
As shown in Table 1, Comparative Examples 1 and 2 used sea-island composite ratios and Comparative Example 3 used homopolyethylene terephthalate as a hardly soluble component. As shown in Table 2, the fabric obtained from any of the raw yarns was a fabric having low denseness and inferior opening properties, and was not a satisfactory raw yarn.

Claims (4)

  A sea-island composite fiber having an easily soluble polymer as a sea component and a hardly soluble polymer as an island component, and the sea: island area ratio in the fiber cross section is 10:90 to 60:40, and the boiling water shrinkage is A sea-island type composite fiber for ultrafine fibers, characterized by being 12% or more. 2. The island-shaped composite fiber for marine ultrafine fibers according to claim 1, wherein island components that satisfy the following requirements (1) to (4) are arranged eccentrically in the fiber cross section.
(1) There is an island missing area where no island component exists on the radial line connecting the fiber center and the outer periphery.
(2) The area around the island missing area is covered with an island component and the area is not exposed on the fiber surface.
(3) The angle (A) formed by both ends in the circumferential direction of the island missing area and the fiber center is 60 ° ≦ A ≦ 270 °.
(4) The ratio of the thickness (S) in the fiber diameter direction of the island missing area to the fiber diameter (R), S / R, is 0.18 ≦ S / R ≦ 0.45.   The sea-island composite fiber for ultrafine fibers according to claim 1 or 2, wherein the island component fiber after elution of sea component has a dry heat shrinkage at 150 ° C of 18.0% or more.   The sea-island type composite for ultrafine fibers according to any one of claims 1 to 3, which has a latent crimp property in which a crimped coil having a crimp pitch of 10 or less appears in the fiber after the sea component is dissolved. fiber.