JP4705451B2 - Manufacturing method of sea-island type composite fiber - Google Patents

Description

  The present invention relates to a method for producing a sea-island composite fiber having a readily soluble polymer as a sea component and a hardly soluble polymer as an island component.

  In the practical application of ultrafine fibers, there is an issue of improving the fiber diameter uniformity and productivity of the ultrafine fibers. Examples of the method for producing such ultrafine fibers include a sea-island type composite spinning method, a direct spinning method, and electrospinning which has recently attracted attention. Among these, the direct spinning method has a problem that it is difficult to reduce the fineness, and electrospinning can produce a nonwoven fabric having a fiber diameter of several tens of nanometers. Due to the large variation and weak strength, there is a limit in application, and the manufacturing method has a problem from the viewpoint of equipment safety and environmental load, such as using solvents and high voltage.

  In contrast, in the sea-island type composite spinning method, for example, a sea component and a polymer that is an island component are blended in a chip state to extract and remove the sea component from the spun fiber to obtain ultrafine fibers (for example, patents). Documents 2 and 3) are known, and such a method is widely used because it can be easily manufactured by a conventional apparatus. However, there is a problem that the ultrafine fibers obtained by this method have a large variation in fiber diameter.

  On the other hand, in order to create ultra-fine fibers having a uniform fiber diameter, a method of dissolving and removing one component from a composite fiber having a sea-island cross-sectional shape is known. What is important here is the high dissolution rate of the sea polymer. When the dissolution rate of the sea component polymer is slow, while the sea component at the center of the fiber cross-section is dissolved, the island component that was in the separated outermost layer is dissolved, causing strength deterioration due to the thickness variation of the island component, Fluff and dyed spots occur.

  In order to increase the dissolution rate of the sea component polymer for such a problem, Patent Document 4 discloses that polyethylene terephthalate obtained by copolymerizing 8 to 15 mol% of 5-sodium sulfoisophthalic acid, isophthalic acid or terephthalic acid in a specific range is used. A composite fiber used for one component has been proposed. However, the spinning speed specifically exemplified in the above prior art is about 1000 to 1200 m / min. In addition, polyethylene terephthalate obtained by copolymerizing a large amount of 5-sodium sulfoisophthalic acid has a problem in that high-speed spinnability is deteriorated and productivity is not improved.

JP 2004-68161 A Japanese Patent Laid-Open No. 3-113082 JP-A-4-126815 Japanese Patent Publication No.61-296120

  An object of the present invention is to overcome the above-mentioned problems and to provide a method for producing a sea-island type composite fiber capable of obtaining ultrafine fibers having a uniform fiber diameter with high productivity.

As a result of intensive studies to solve the above problems, the present inventors have reached the present invention. That is, according to the present invention, a melted polymer in which an easily soluble polymer is composed of a sea component and a hardly soluble polymer is composed of an island component is melt-discharged from a spinneret and wound up to produce a sea-island composite fiber. In this method, the weight ratio of the sea component to the island component is 40:60 to 10:90, and the easily soluble polymer constituting the sea component is polyethylene having 6 to 12 mol% of 5-sodium sulfoisophthalic acid and a molecular weight of 4000 to 12000. Polyethylene terephthalate copolymerized with 3 to 10% by weight of glycol, and the fiber diameter (R) of the composite fiber, the average diameter (r) of island components in the cross section of the composite fiber, and the cross section of the composite fiber When four straight lines are drawn every 45 degrees through the center, the average value (S) of the distance between the island components on this straight line and A sea-island type composite characterized in that the distance (So) between the island component and the fiber outer periphery satisfies the following relational expressions (I) to (III), and the take-up speed is 2000 to 5000 m / min. A method of manufacturing a fiber is provided.
0.01 ≦ r / R ≦ 0.06 (I)
0.001 ≦ S / R ≦ 0.015 (II)
0.5 ≦ So / S ≦ 1.5 (III)

  ADVANTAGE OF THE INVENTION According to this invention, the sea-island type | mold composite fiber from which the melt | dissolution rate of a sea component is quick and the ultrafine fiber with a uniform fiber diameter is obtained can be manufactured stably with high spinning speed with high productivity. For this reason, it not only improves productivity but also saves energy, and exhibits excellent effects in terms of cost performance and the environment.

The present invention is a method for producing a sea-island type composite fiber by melt-discharging a molten polymer, which is a sea-island type compound comprising an easily soluble polymer as a sea component and a hardly soluble polymer as an island component, from a composite spinneret and winding it up. is there.
In the present invention, the easily soluble polymer and the hardly soluble polymer are the two types of polymers having different solubility in the alkaline aqueous solution. It is called a soluble polymer.

  In the present invention, the weight ratio of sea component: island component of the sea-island type composite fiber needs to be in the range of 40:60 to 10:90, preferably in the range of 30:70 to 15:85. When the proportion of the sea component exceeds 40%, the amount of the solvent necessary for dissolving the sea component increases, which not only decreases productivity but also is not preferable in terms of safety and environmental load. On the other hand, when the proportion of the sea component is less than 10%, there is a high possibility that the islands are stuck together, and it becomes difficult to obtain ultrafine fibers having a uniform fiber diameter.

In the present invention, the readily soluble polymer constituting the sea component is a specific copolymer polyester described below, and in the sea-island type composite fiber, the fiber diameter (R) of the composite fiber, the cross section of the composite fiber The average diameter (r) of the island components at, and the average value (S) of the spacing of the island components on this straight line when four straight lines are drawn at 45 degree angles to each other through the center of the composite fiber cross section, It is important that the distance (So) between the island component closest to the fiber outer periphery and the fiber outer periphery satisfy the following relational expressions (I) to (III). Thereby, the sea-island type composite fiber from which ultrafine fibers having a uniform fiber diameter can be obtained can be produced with high productivity at a fast take-up speed described later.
r / R ≦ 0.08 (I)
S / R ≦ 0.02 (II)
0.1 ≦ So / S ≦ 1.5 (III)

  That is, the easily soluble polymer constituting the sea component of the sea-island composite fiber is a polyethylene terephthalate system obtained by copolymerizing 6 to 12 mol% of 5-sodium sulfoisophthalic acid and 3 to 10 wt% of polyethylene glycol having a molecular weight of 4000 to 12000. It must be a copolyester. In addition, 5-sodium sulfoisophthalic acid contributes to hydrophilicity and melt viscosity improvement, and polyethylene glycol (PEG) contributes to hydrophilicity improvement.

  At this time, if the amount of 5-sodium sulfoisophthalic acid is less than 6 mol%, the dissolution rate of the easily soluble polymer constituting the sea component is low, and the sea component in the center of the fiber cross section is not completely dissolved and removed. Regardless, the island component of the surface section of the already separated fiber cross-section is further eroded, causing not only the thickness of the island component, but also the deterioration of strength, which causes fluff and dyed spots. Arise. On the other hand, when it exceeds 12 mol%, the intrinsic viscosity is lowered and the high-speed spinnability is deteriorated.

  Moreover, when the copolymerization amount of PEG exceeds 3% by weight, the dissolution rate of the sea component decreases, and the same problem as in the case where 5-sodium sulfoisophthalic acid is less than 6 mol% occurs. On the other hand, when the copolymerization amount of PEG exceeds 10% by weight, the melt viscosity is lowered and the high-speed spinnability is deteriorated. In addition, as the molecular weight of PEG increases, there is an effect of increasing hydrophilicity, which is considered to be due to its higher order structure, but since the reactivity becomes poor and a blend system is formed, in terms of heat resistance in spinning and high-speed spinning stability Since a problem arises, the molecular weight needs to be in the range of 4000-12000.

  The combination of polymers constituting the sea-island composite fiber of the present invention preferably satisfies the following two points. The two points are (1) the melt viscosity of the sea component during melt spinning is larger than the melt viscosity of the island component, and (2) the dissolution rate ratio of the polymer constituting the sea component to the polymer constituting the island component is 500 times. That is all.

  When the melt viscosity of the sea component at the time of melt spinning is larger than the melt viscosity of the island component, the sea-island cross-section formability is improved. If this condition is satisfied, even if the composite weight ratio of the sea components is 50% or less, it is difficult to form fibers in which the islands are mostly stuck together. When the islands are stuck together, when sea components are dissolved and removed, not only ultrafine fibers but also irregular fibers are created, and problems such as dyed spots and pilling are likely to occur. A particularly preferred melt viscosity ratio (sea / island) is in the range of 1.1 to 2.0, particularly 1.3 to 1.5. If this ratio is less than 1.1, the island components are likely to stick together during melt spinning, whereas if it exceeds 2.0, the difference in viscosity is too large and the spinning tone tends to decrease. In addition, as the temperature at the time of melt spinning, it is assumed that spinning is performed at a temperature that is 10 to 40 ° C. higher than the melting point or softening point of the higher melting point or softening point of the polymer constituting the sea component or island component.

  When the dissolution rate ratio of the polymer constituting the sea component to the polymer constituting the island component is 500 times or more, the island separability is improved. When the dissolution rate ratio is less than 500 times, the island component of the separated fiber cross-section surface layer is dissolved because the fiber diameter is small while the sea component at the center of the fiber cross-section is dissolved. Despite being reduced in weight, the sea component at the center of the fiber cross-section cannot be completely dissolved and removed, resulting in the thickness deterioration of the island component and the deterioration of strength due to solvent erosion, resulting in fluff and dyed spots. Problems arise. Here, the dissolution rate ratio is the dissolution rate constant of each polymer, and the dissolution rate constant is a weight loss rate (insoluble weight fraction = 1−weight reduction rate) with respect to the weight loss time at 95 ° C. in a 4% NaOH aqueous solution. ), Treatment time, and fiber radius.

ｋは溶解速度定数、Ｒｗは不溶解重量分率、ｔは処理時間、ｒ0は繊維半径である。

k is the dissolution rate constant, Rw is the insoluble weight fraction, t is the treatment time, and r0 is the fiber radius.

  The polymer constituting the island component preferably satisfies the above-mentioned two points, and examples thereof include any polymer such as a polyester polymer, a polyamide polymer, a polystyrene polymer, and a polyethylene polymer that have particularly good fiber formation. Among these, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, nylon 6, and nylon 66 are preferable for clothing. On the other hand, in industrial materials and medical applications, polystyrene, polyethylene and the like that are resistant to water, acid, and alkali are preferable in terms of durability. Furthermore, the island component is not limited to a round cross section, and may be an irregular cross section.

In the present invention, as described above, when the sea-island type composite fiber passes through the center of the cross-section of the composite fiber and draws four straight lines at an angle of 45 degrees to each other, the interval between the island components on the straight line is reduced. The average value (S) needs to satisfy the following relational expressions (I) to (II).
r / R ≦ 0.08 (I)
S / R ≦ 0.02 (II)
0.1 ≦ So / S ≦ 1.5 (III)

Here, when the r / R value exceeds 0.08, the S / R value exceeds 0.02, or the So / S exceeds 1.5, the high-speed spinnability is deteriorated. . More preferably, it is the following range. Moreover, when So / S is less than 0.1, island components are easily stuck together, and ultrafine fibers having a uniform fiber diameter cannot be obtained.
0.01 ≦ r / R ≦ 0.06
0.001 ≦ S / R ≦ 0.015
0.5 ≦ So / S ≦ 1.5

  In the composite fiber, the number of islands is particularly preferably 400 or more. The large number of islands allows the sea components to be finely dispersed on the cross section, improving high-speed spinnability and improving productivity. What is important here is that the sea components are uniformly finely dispersed in the cross section of the sea island. There should be no bias in sea components. Thereby, the poor high-speed spinnability can be overcome. Further, by increasing the number of islands, the fineness of the ultrafine fibers obtained by dissolving and removing the sea components becomes remarkable, and the softness, glossiness, etc. specific to the ultrafine fibers can be expressed. Here, when the number of islands is less than 400, it is not dispersed so much, so that the high-speed spinnability is deteriorated and the cost performance is deteriorated. Further, even if sea components are dissolved and removed, ultrafine fibers having a small fiber diameter cannot be obtained. If the number of islands increases too much, not only the production cost of the spinneret increases, but also the workability itself tends to decrease.

  Next, the diameter of the island component needs to be in the range of 10 to 1500 nm, preferably 100 to 1000 nm. If the diameter is less than 50 nm, the physical properties and the fiber form are unstable due to the instability of the fiber structure. On the other hand, if it exceeds 1500 nm, the softness and glossiness peculiar to ultrafine fibers cannot be obtained.

  Some of these sea-island composite undrawn yarns for ultrafine fibers exhibit a yield point corresponding to a partial breakage of sea components in the unloading curve at room temperature. This is a phenomenon observed when the sea part solidifies faster than the island part, and the island part is oriented due to the influence of the sea part. The first yield point means a partial break point of the sea component, and after the yield point, an island portion having a low orientation extends. And the sea island part breaks at the breaking point of the load-elongation curve. These phenomena can also be explained from the fact that the primary yield point shifts to the initial stage as the spinning speed increases. Of course, the unloading curve at room temperature is not limited to the above, and may be a normal unloading curve.

  As the spinneret used for melt spinning in the present invention, any one such as a hollow pin group for forming an island component or a group having a fine hole group can be used. For example, a spinneret may be used in which an island component extruded from a hollow pin or a fine hole and a sea component flow that is designed to fill the gap between the island component are joined and compressed to form a cross section of the sea island. . Examples of spinnerets that are preferably used are shown in FIGS. 1 and 2, but are not necessarily limited thereto. FIG. 1 shows a method of discharging a hollow pin into a sea component resin reservoir and compressing it by joining, and FIG. 2 shows a method of forming an island by a fine hole method.

  Each figure will be described more specifically. In the spinneret 1 shown in FIG. 1, the melted island component polymer in the island component polymer reservoir 2 before distribution is in the island component polymer introduction passage 3 formed by a plurality of hollow pins. On the other hand, the molten sea component polymer is introduced into the pre-distribution sea component polymer reservoir 5 through the sea component polymer introduction passage 4. The hollow pin forming the island component polymer introduction passage 3 passes through the sea component polymer reservoir 5 and is located at the center of the entrance of each of the plurality of core-sheath type composite flow passages 6 formed thereunder. The part opens downward. The island component polymer flow is introduced from the lower end of the island component polymer introduction passage 3 into the central portion of the core-sheath type composite flow passage 6, and the sea component polymer flow in the sea component polymer reservoir 5 is Is introduced so as to enclose the island component polymer, and a core-sheath type composite flow having the island component polymer flow as a core and a sea component polymer flow as a sheath is formed. It introduce | transduces in the funnel-shaped confluence | merging channel | path 7, and in this confluence | merging channel | path 7, each sheath part adjoins each other, and a sea-island type compound flow is formed. The sea-island type composite flow gradually decreases in the horizontal cross-sectional area while flowing down in the funnel-shaped merge passage 7 and is discharged from the discharge port 8 at the lower end of the merge passage 7.

  In the spinneret 11 shown in FIG. 2, the island component polymer reservoir 2 and the sea component polymer reservoir 5 are connected to an island component polymer introduction passage 13 formed of a plurality of through holes. The molten island component polymer in the island component polymer reservoir 2 is distributed to the plurality of island component polymer introduction passages 13 and is accommodated in the sea component polymer reservoir 5 through the plurality of island component polymer introduction passages 13. It passes through the melted sea component polymer and flows into the core-sheath type composite flow passage 6 and flows down the central portion thereof. On the other hand, the sea component polymer in the sea component polymer reservoir 5 flows down into the core-sheath composite flow passage 6 so as to surround the island component polymer flowing down the central portion thereof. As a result, a plurality of core-sheath type composite flows are formed in the plurality of core-sheath type composite flow passages 6, and a plurality of core-sheath type composite flows are formed in the funnel-shaped join passage 6. In the same manner as in FIG. 1, it flows down while forming a sea-island type composite flow, further reduces its horizontal cross-sectional area, and is discharged from the discharge port 8.

  The discharged sea-island type composite fiber is solidified by cooling air and wound up. The winding speed is preferably 2000 to 5000 m / min. Particularly preferred is 2500 to 4000 m / min. If it is less than 2000 m / min, the productivity is not sufficient. If it exceeds 5000 m / min, the spinning stability is poor.

The elongation of the sea-island composite fiber obtained in the present invention is preferably 100% or more. If it is more than this, a high-strength ultrafine fiber can be produced because of a high draw ratio, and application development is possible not only for fiber products but also in a wide range of fields.
The obtained undrawn yarn can be adjusted to desired strength, elongation and heat shrinkage characteristics. The stretching step may be any of a method such as a separate stretching step after winding, or a method of simultaneously spinning and performing winding after the stretching step.
The obtained undrawn yarn can be false twisted, and the obtained processed yarn has excellent processed physical properties.

  FIG. 3 is a cross-sectional explanatory view of an embodiment (21) of the sea-island type composite fiber of the present invention, which is composed of a sea component 22 and a large number of island components 23 arranged separately from each other in the sea component 22. Yes. A method for measuring the interval between island components will be described with reference to FIG. In FIG. 3, when the four straight lines 25-1, 25-2, 25-3, and 25-4 are drawn on the cross section 21 through the center 24 at an angle of 45 degrees with respect to each other, The distance between the island components on the four straight lines is measured, and the maximum value Sm and the distance So between the island component closest to the fiber outer periphery and the fiber outer periphery are determined, and the average value of the intervals between the island components is determined. S is calculated. In FIG. 3, four linear island components are drawn and described, and the description of the island components is omitted.

  The sea-island type composite fiber produced according to the present invention, or the ultrafine fiber bundle obtained by removing sea components from the composite fiber is a yarn, braided yarn, spun yarn, woven fabric using at least a part thereof, It can be used as an intermediate product such as felt, nonwoven fabric, and artificial leather.

  In addition, since the above-mentioned ultrafine fiber bundle has high toughness, the intermediate products include jackets, skirts, pants, underwear and other clothing, sports clothing, clothing materials, carpets, sofas, curtains, interiors, and car seats. Interior goods, cosmetics, cosmetic masks, wiping cloths, health goods, and other daily necessities, environment and industrial materials such as abrasive cloths, filters, harmful substance removal products, battery separators, sutures, scaffolds, artificial blood vessels, blood filters It can be used for a wide range of medical purposes.

  Furthermore, because the above-mentioned ultrafine fiber side has a large specific area, it has excellent adsorption and absorption characteristics.For example, it can adsorb drugs such as proteins and vitamins, health and beauty promoting drugs, anti-inflammatory agents, disinfectants, etc. Can be used. On the other hand, since it has sustained release properties, it can be used for pharmaceutical and hygiene applications such as drug delivery systems.

Hereinafter, the present invention will be described more specifically with reference to examples. Each evaluation item was measured by the following method.
(1) Melt viscosity measurement The polymer after drying is set in an orifice set at the melter melting temperature at the time of spinning, melted and held for 5 minutes, and then extruded under several levels of load. The shear rate and melt viscosity at that time Plot. By gently connecting the plots, a shear rate-melt viscosity curve is created, and the melt viscosity when the shear rate is 1000 sec- ¹ is observed.
(2) Sea-island cross-section formation The sea-island state was observed using an optical microscope and evaluated in two stages.
○: No island sticking part ×: With island sticking part (3) Dissolution rate measurement Winding the yarn at a spinning speed of 2000 m / min with a 0.3φ-0.6L × 24H base for each of the sea and island components, and further Stretching is performed so that the residual elongation is in the range of 30 to 60%, and a 75 de / 24 fil multifilament is produced. The weight loss rate was calculated from the dissolution time and the dissolution amount at a bath ratio of 100 at a temperature at which the solvent was dissolved in each solvent.
(4) When the fiber diameter (R), the average diameter (r) of the island component, and four straight lines are drawn every 45 degrees through the center of the fiber cross section, the island component on this straight line Average spacing (S) and spacing between the island component closest to the fiber circumference and the circumference (So)
Fiber cross-sectional photographs were taken with a transmission electron microscope TEM at a magnification of 30000, and measured and calculated by the method described above.
(5) Load-elongation curve The weight of 9000 m of the sea-island type composite fiber was measured three times to obtain the fineness from the average value. Then, a load-elongation curve was obtained at room temperature with an initial sample length of 100 mm and a pulling speed of 200 m / min. When the yield point corresponding to the partial breakage of the sea component appeared in the load-elongation curve, the difference between the intermediate yield point and the breaking elongation was obtained from the chart paper.
(6) High-speed spinnability The semi-stretched yarns in the examples were manufactured, and those that could be wound for 30 minutes were marked with ◯, and those that could not be wound were marked with ×.
(7) Fiber diameter of ultrafine fiber and uniformity of fiber diameter By 30,000 times TEM observation of ultrafine fiber after dissolution and removal of sea components, the average fiber diameter is calculated for the ultrafine fiber in one composite fiber, and the maximum − A sample having a minimum width smaller than 50% of the average fiber diameter was evaluated as “◯”, and a sample having a minimum width as “×”.
(8) Productivity As an index of productivity, a draw ratio × spinning speed of 5000 or more was evaluated as ◯, and 5000 or less was evaluated as ×. This index means the winding amount per unit time when manufacturing FOY having the same elongation.
(9) Texture of ultrafine fibers A sensory test was conducted on seven monitors and evaluated in two stages.
○: 5 or more people who evaluated that there was a slimy feeling peculiar to ultrafine fibers ×: 5 or less who evaluated that there was a slimy feeling peculiar to ultrafine fibers

[Example 1]
Polyethylene terephthalate having a melt viscosity of 1,200 poise at 285 ° C. for the island component, and 4 wt%, 5-sodium sulfoisophthalic acid (SIP) of polyethylene glycol (PEG) having an average molecular weight of 4000 having a melt viscosity of 1,600 poise at 285 ° C. A modified polyethylene terephthalate copolymerized with 8 mol% was melt-discharged at a spinning temperature of 285 ° C. using a spinneret shown in FIG. The melt-discharged yarn could be stably wound at a winding speed of 3000 m / min. The results are shown in Table 1. As a result, a yield point corresponding to a partial fracture of the sea component is expressed in a load-elongation curve at room temperature (hereinafter sometimes referred to as a load-elongation curve), and a high stretch ratio with an elongation of 330%. A possible high elongation undrawn yarn was obtained. The obtained undrawn yarn was roller-drawn at a drawing temperature of 90 ° C. and a draw ratio of 2.4 times, and then heat-set at 150 ° C. and wound to obtain a drawn yarn of 20 dtex / 10 fil. Tube knitting was made and reduced by 40% at 95 ° C. with 4% NaOH aqueous solution. Here, the dissolution rate ratio of the sea component polymer to the island component polymer was 1200 times. When the cross section of the fiber was observed, a uniform ultrafine fiber group was formed. The average value of the ultrafine fiber diameter was 470 nm. The productivity index was 7200, and it was possible to efficiently produce ultra-fine fibers with a uniform fiber diameter by high-speed spinning. The results are further shown in Table 1. In the table, the numbers described in parentheses below the polymers of the sea and island components respectively indicate the melt viscosity.

[Example 2]
The same sea-island polymer as in Example 1 was used at the same sea-island ratio, spun using a base having 980 islands, and wound at a winding speed of 5000 m / min. As a result, a high elongation undrawn yarn capable of a high draw ratio with an elongation of 200% in which a yield point corresponding to the partial breakage of the sea component was expressed in the unloading curve at room temperature was obtained. The obtained undrawn yarn was roller-drawn at a drawing temperature of 90 ° C. and a draw ratio of 2.0 times, and then heat-set at 150 ° C. and wound to obtain a drawn yarn of 20 dtex / 10 fil. Cylinder knitting was made and reduced by 40% at 95 ° C. with 4% NaOH aqueous solution. The results are shown in Table 1.

[Example 3]
The island component was copolymerized with polyethylene terephthalate having a melt viscosity at 285 ° C. of 1200 poise, and the sea component was copolymerized with 3 wt% of polyethylene glycol having an average molecular weight of 4000 having a melt viscosity of 1700 poise at 285 ° C. and 10 mol% of 5-sodium sulfoisophthalic acid. The modified polyethylene terephthalate was used, the ratio of sea: island was 10:90, spinning was performed using a die having 800 islands, and wound at a winding speed of 4000 m / min. As a result, the yield point corresponding to the partial breakage of the sea component is not expressed in the unwinding curve at room temperature, and the elongation is 250%, and a high elongation unstretched yarn capable of a high draw ratio is obtained. It was. The obtained undrawn yarn was roller-drawn at a drawing temperature of 90 ° C. and a draw ratio of 2.2 times, and then heat-set at 150 ° C. and wound to obtain a drawn yarn of 20 dtex / 10 fil. Cylinder knitting was made and reduced by 10% at 95 ° C. with 4% NaOH aqueous solution. Here, the dissolution rate ratio of the sea component polymer to the island component polymer was 1500 times. The results are shown in Table 1.

[Example 4]
The island component was copolymerized with polyethylene terephthalate having a melt viscosity of 1300 poise at 285 ° C., and the sea component was copolymerized with 8 wt% of polyethylene glycol having an average molecular weight of 4000 having a melt viscosity of 1800 poise at 285 ° C. and 7 mol% of 5-sodium sulfoisophthalic acid. Using modified polyethylene terephthalate, the weight ratio of sea: island was 30:70, and spinning was performed using a die having 500 islands, and wound at a winding speed of 2000 m / min. As a result, an undrawn yarn having an elongation of 350% in which a yield point corresponding to the partial breakage of the sea component was developed in the unloading curve at room temperature was obtained. The obtained undrawn yarn was roller-drawn at a drawing temperature of 90 ° C. and a draw ratio of 2.7 times, and then heat-set at 150 ° C. and wound to obtain a 20 dtex / 10 fil false twisted yarn. Cylinder knitting was made and reduced by 10% at 95 ° C. with 4% NaOH aqueous solution. Here, the dissolution rate ratio of the sea component polymer to the island component polymer was 1200 times. The results are shown in Table 1.

[Comparative Example 1]
The same sea-island polymer as in Example 1 was used and spun at the same sea-island ratio using the same number of islands but different bases. So / S was 3, and after about 5 minutes from the start of winding, the single yarn fell from the spinning tube, so that it could not be wound up, and the high-speed spinning property was poor, so that an ultrafine fiber could not be produced.

[Comparative Example 2]
The same sea-island polymer as in Example 1 was used, and the sea: island was spun at 30:70 using a base having 100 islands. Sea-island cross-section formation was good, but r / R was 0.08, S / R was 0.015, and winding took place because the single yarn fell from the spinning tube in about 1 minute after starting winding. It was not possible to produce ultra-fine fibers due to poor high-speed spinnability.

[Comparative Example 3]
The island component was copolymerized with polyethylene terephthalate having a melt viscosity at 285 ° C. of 1200 poise, and the sea component was copolymerized with 2 wt% of polyethylene glycol having an average molecular weight of 4000 having a melt viscosity of 1650 poise at 285 ° C. and 3 mol% of 5-sodium sulfoisophthalic acid. The modified polyethylene terephthalate was spun using the same number of islands with the same sea-island ratio as in Example 3 and wound up at a winding speed of 3000 m / min. Reduced by 10% at 95 ° C. with aqueous solution. Since the dissolution rate ratio of the sea component polymer to the island component polymer is 100 times, which is insufficient, the island on the fiber surface is also reduced, although the sea equivalent is reduced, and most of the center of the fiber cross section is reduced. Since the sea was not reduced, the ultrafine fiber did not have a uniform fiber diameter, and a specific softness could not be obtained.

[Comparative Example 4]
The island component was copolymerized with polyethylene terephthalate having a melt viscosity at 285 ° C. of 1200 poise, and the sea component was copolymerized with 20 wt% of polyethylene glycol having an average molecular weight of 4000 having a melt viscosity of 900 poise at 285 ° C. and 8 mol% of 5-sodium sulfoisophthalic acid. The modified polyethylene terephthalate was spun with a weight ratio of sea: island 40:60 using a die having 400 islands and wound at a winding speed of 4000 m / min. However, the sea-island cross-sectional formability was poor. Specifically, although islands exist independently on the fiber surface portion, a cross section is formed in the fiber center portion so that the sea component surrounds the joined island. Therefore, even if the amount was reduced, ultrafine fibers could not be formed.

  ADVANTAGE OF THE INVENTION According to this invention, the sea-island type | mold composite fiber from which the melt | dissolution rate of a sea component is quick and the ultrafine fiber with a uniform fiber diameter is obtained can be manufactured stably with high spinning speed with high productivity. For this reason, it not only improves productivity but also saves energy, and exhibits excellent effects in terms of cost performance and the environment. Therefore, the industrial value is extremely high.

FIG. 2 is a partial cross-sectional explanatory view of an example of a spinneret used for spinning the sea-island type composite fiber of the present invention. FIG. 6 is a cross-sectional explanatory view of a part of another example of the spinneret used for spinning the sea-island type composite fiber of the present invention. It is a section explanatory view of one embodiment of the sea-island type composite fiber of the present invention.

Claims (4)

In a method of manufacturing a sea-island type composite fiber by melting and discharging a melt polymer, which is composed of an easily soluble polymer as a sea component and a hardly soluble polymer as an island component, in a sea-island shape, and winding this from a spinneret, The weight ratio of the components is 40:60 to 10:90, and the easily soluble polymer constituting the sea component is 6 to 12 mol% of 5-sodium sulfoisophthalic acid and 3 to 10 wt% of polyethylene glycol having a molecular weight of 4000 to 12000. Copolymerized polyethylene terephthalate, and the fiber diameter (R) of the composite fiber, the average diameter (r) of the island component in the cross section of the composite fiber, and the angle of 45 degrees to each other through the center of the cross section of the composite fiber When four straight lines are drawn, the average value (S) of the distance between the island components on the straight line and the distance between the island component closest to the fiber outer periphery and the fiber outer periphery (S ) Has to satisfy the following relational formula (I) ~ (III), the method of producing sea-island type composite fiber characterized by a further take-up speed of 2000~5000m / min.
0.01 ≦ r / R ≦ 0.06 (I)
0.001 ≦ S / R ≦ 0.015 (II)
0.5 ≦ So / S ≦ 1.5 (III)   The method for producing a sea-island type composite fiber according to claim 1, wherein the number of islands is 400 or more and the average diameter (r) of the island component is 10 to 1500 nm in the cross section of the sea-island type composite fiber.   The method for producing a sea-island composite fiber according to claim 1, wherein the elongation of the sea-island composite fiber is 100% or more. The method for producing a sea-island composite fiber according to claim 1, wherein the dissolution rate ratio of the easily soluble polymer to the hardly soluble polymer is 500 times or more.
The above dissolution rate ratio is the dissolution rate constant of each polymer, and the dissolution rate constant is a 4% NaOH aqueous solution at 95 ° C. and the weight loss rate (insoluble weight fraction = 1−weight loss rate). ), Treatment time, and fiber radius.

k is the dissolution rate constant, Rw is the insoluble weight fraction, t is the treatment time, and r0 is the fiber radius.

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