JP2018168510A - Porous hollow fiber - Google Patents

Abstract

To provide a porous hollow fiber uniform in diameter of a hollow part even when percentage of the hollow part is large, having light weight and high in heat insulation property.SOLUTION: There is provided a porous hollow fiber obtained by removing an island component from a plurality of sea-island-type composite fibers containing an alkali solution easily soluble polymer as the island component and low soluble polymer as a sea component, in which the number of the hollow part observed in a fiber cross section with right angle to a length direction of the fiber is 100 or more per 1 porous hollow fiber, intervals of neighboring hollow parts are 100 nm or more, diameters of each hollow part are in a range of 10 to 1000 nm, variation of diameter of the hollow part (CV value) is 30% or less, the low soluble polymer contains a specific metal salt compound, the content of the same is 0.1 to 3.0 mol% based on 100 mol% of the low soluble polymer.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a porous hollow fiber and a sea-island type composite fiber used for the production thereof.

  Polyester fibers have various excellent properties including mechanical properties, and are used in various applications and fields including clothing applications. However, polyester fibers are said to be harder in texture than natural fibers, have no water absorption, and are not preferable in terms of touch, and these problems have been solved by changing the cross-sectional shape of the fibers. .

  In clothing applications, in order to obtain high fabric strength while being lightweight, hollow fibers having a hollow cross-sectional shape are used. In order to obtain hollow fibers, the spinneret is made into a hollow shape, or using a composite fiber (usually called conjugate spinning) device, polyvinyl alcohol resin is used at the fiber center (core), and the fibers A core-sheath composite fiber using a polyester resin on the outer periphery (sheath part) is made into a hollow fiber having a high hollow ratio by eluting the polyvinyl alcohol resin in the core part after spinning and leaving the polyester fiber in the sheath part. It has been proposed to obtain (for example, Patent Document 1). However, in the method of obtaining hollow fibers by forming the spinneret into a hollow shape, spun yarn is likely to occur, and it is difficult to perform stable production. On the other hand, in the method of obtaining hollow fibers from the core-sheath composite fiber, it is relatively easy to increase the hollow ratio, but the area per discharge hole of the spinneret becomes enormous, and the core portion It is difficult to control the position of the resin component, and it is difficult to obtain uniform fibers. In particular, with long fibers, it is difficult to completely elute the resin component in the core. So far, a good porous hollow fiber in which many hollow portions are uniformly formed in the yarn length direction and the yarn cross-sectional direction has not been obtained.

  By the way, Japanese Patent Application Laid-Open No. 9-241194 (Patent Document 2) and Japanese Patent Application Laid-Open No. 2001-115334 (Patent Document 3) describe a core part having a hollow cross section perpendicular to the fiber axis and an outside of the core part. A hollow fiber having a shape including a fin portion protruding from the surface and extending along the length direction of the core portion has been proposed. However, with this shape, the porosity in the multifilament state is low, resulting in inferior lightness.

  Moreover, although hollow fiber is described also in Unexamined-Japanese-Patent No. 2008-57060 (patent document 4), since this hollow fiber has few number of fins and is a highly atypical cross section, it is silk of a fiber. The factor (strength × √elongation) is low, fluff is frequently generated in the drawing process, and the hollowness and porosity are greatly reduced due to deformation of the fiber cross section.

JP 2002-173824 A JP-A-9-241941 JP 2001-115334 A JP 2008-57060 A

  An object of the present invention is to provide a porous hollow fiber that has a uniform hollow portion diameter even if the proportion of the hollow portion is large, is lightweight, and has high heat retention.

  The present invention is also a sea-island composite fiber used for obtaining a porous hollow fiber having a uniform hollow part diameter, light weight and high heat retention even when the proportion of the hollow part is large. Providing sea-island composite fibers that can easily remove island components even when the component content is high, have sufficient mechanical strength to withstand practical use, and obtain porous hollow fibers with an extremely large number of hollow portions The purpose is to do.

[Porous hollow fiber]
That is, the present invention is a porous hollow fiber obtained by removing the island component from a plurality of sea-island type composite fibers having an easily soluble polymer as an island component and a hardly soluble polymer as a sea component, The number of hollow portions observed in the fiber cross section perpendicular to the length direction is 100 or more per porous hollow fiber, the interval between adjacent hollow portions is 100 nm or more, and each of the hollow portions The diameter is in the range of 10 to 1000 nm, the variation in the diameter of the hollow part (CV value) is 30% or less, and the hardly soluble polymer contains a metal salt compound represented by the following formula. The porous hollow fiber is characterized in that the amount is 0.1 to 3.0% by weight per 100% by weight of the hardly soluble polymer.

[Sea-island type composite fiber]
The present invention is also a sea-island type composite fiber having an easily soluble polymer as an island component and a hardly soluble polymer as a sea component, and is observed in a fiber cross section perpendicular to the fiber length direction of the composite fiber. The number of island components is 100 or more, the interval between adjacent island components is 100 nm or more, and the diameter of each island component is in the range of 10 to 1000 nm. ) Is 30% or less, and the hardly soluble polymer contains a metal salt compound represented by the following formula, and the content thereof is 0.1 to 3.0% by weight per 100% by weight of the hardly soluble polymer. This is a sea-island type composite fiber.

  According to the present invention, it is possible to provide a porous hollow fiber that has a uniform hollow portion diameter and is lightweight and has high heat retention even when the proportion of the hollow portion is large.

  The present invention is also used to obtain porous hollow fibers, and can easily remove island components even when the content ratio of island components in sea-island composite fibers is high, and has sufficient mechanical strength to withstand practical use. It is possible to provide a sea-island type composite fiber that can obtain a porous hollow fiber having an extremely large number of hollow portions.

FIG. 2 is a cross-sectional explanatory view of a part of a spinneret used for spinning the sea-island type composite fiber of the present invention. FIG. 2 is a cross-sectional explanatory view of a part of a spinneret used for spinning the sea-island type composite fiber of the present invention. It is a cross-sectional explanatory drawing of an example of the sea-island type composite fiber of this invention.

  Hereinafter, the present invention will be described in detail.

[Porous hollow fiber]
In the porous hollow fiber of the present invention, the number of hollow portions observed in the fiber cross section perpendicular to the fiber length direction is 100 or more, preferably 500 or more per fiber. If the number of hollow portions is less than 100, sufficient performance cannot be obtained with respect to lightness, heat retention and soft feeling of the porous hollow fiber. If the number of hollow portions is excessively large, the manufacturing cost of the spinneret increases, and the processing accuracy of the spinneret itself tends to decrease. Therefore, the number of hollow portions is preferably 1000 or less.

  The diameter of the hollow part of the porous hollow fiber is 10 to 1000 nm, preferably 100 to 700 nm. If the diameter of the hollow portion is less than 10 nm, the fiber structure itself is unstable and the hollow forming property becomes unstable, and if it exceeds 1000 nm, the heat retention characteristic of the porous hollow fiber cannot be obtained. In addition, the quality of a fiber improves, so that the diameter of the hollow part of a porous hollow fiber is uniform.

  The interval between the adjacent hollow portions observed in the fiber cross section perpendicular to the fiber length direction is 100 nm or more, preferably 200 nm or more. When the thickness is less than 100 nm, the mechanical strength of the porous hollow fiber obtained after dissolving and removing the island component cannot be sufficiently secured. The space between the hollow part and the adjacent hollow part efficiently forms fine pores penetrating in the sea component of the sea-island composite fiber when producing the porous hollow fiber, thereby obtaining a highly uniform porous hollow fiber. From the viewpoint, it is preferably less than 500 nm.

  The variation (CV value) in the diameter of the hollow part is preferably 0 to 30%, more preferably 0 to 20%, particularly from the viewpoint of forming the hollow part uniformly in the yarn length direction and the yarn cross-sectional direction in long fibers. More preferably, it is 0 to 15%. A low CV value means that there is little variation in fineness and that the porous hollow fiber is uniform.

  The porous hollow fiber of the present invention preferably has a tensile strength of 1.0 to 6.0 cN / dtex. By providing a tensile strength in this range, it is possible to cope with many applications that require a tensile strength.

  The porous hollow fiber of the present invention preferably has a cutting elongation of 15 to 60%. By having a cut elongation in this range, it has strength that can be applied and developed for various purposes.

[Easily soluble polymer]
As the easily soluble polymer used for the island component of the sea-island type composite fiber used for obtaining the porous hollow fiber of the present invention, the solubility in an alkaline aqueous solution is higher than that of the hardly soluble polymer used for the sea component, which is higher than the hardly soluble polymer. Also use a polymer that dissolves easily. This easily soluble polymer is a polymer that dissolves easily in an alkaline aqueous solution. For example, polylactic acid, ultrahigh molecular weight polyalkylene oxide condensation polymer, polyethylene glycol compound copolymerized polyester, and polyethylene glycol compound and 5-sodium sulfoisophthalic acid. Copolyester with can be used.

  Among these, in order to achieve both easy solubility in alkali and sea-island cross-sectional formability, an easily soluble polymer is obtained by converting 6 to 12 mol% of 5-sodium sulfonic acid and 94 to 88 mol% of terephthalic acid into a dicarboxylic acid. It is preferably a copolyester comprising 3 to 10% by weight of polyethylene glycol having a molecular weight of 4000 to 12000 and 97 to 90% by weight of diethylene glycol as diol components. This copolyester preferably has an intrinsic viscosity of 0.4 to 0.6.

  Copolymerization component 5-sodium isophthalic acid in this copolymerized polyester contributes to improving the hydrophilicity and melt viscosity of the resulting copolymerized polyester, and polyethylene glycol improves the hydrophilicity of the resulting copolymer.

  The molecular weight of polyethylene glycol in this copolyester is 4000-12000. When the molecular weight exceeds 12,000, hydrophilicity, which is considered to be due to its higher order structure, is increased, but the reactivity with the dicarboxylic acid component is reduced, and the resulting reaction product becomes a blend system. Stability will be insufficient. On the other hand, if the molecular weight is less than 4000, the hydrophilicity is insufficient and it is difficult to remove the island components.

  When the copolymerization amount of polyethylene glycol in the copolymerized polyester is less than 3% by weight, the hydrophilicity is insufficient, and it is difficult to remove the island component with an alkaline aqueous solution, which is not preferable. On the other hand, when the copolymerization amount of polyethylene glycol exceeds 10% by weight, since polyethylene glycol originally has an effect of lowering melt viscosity, the viscosity of the resulting copolymer is too low, and the object of the present invention to provide a porous hollow fiber It is difficult to achieve this, which is not preferable.

[Dissolution rate ratio]
The dissolution rate ratio (island component / sea component) of the easily soluble polymer of the island component and the hardly soluble polymer of the sea component is preferably 200 or more. When the dissolution rate ratio is less than 200, while the island component at the center of the cross section of the obtained sea-island type composite fiber is dissolved with the alkaline aqueous solution, a part of the sea component at the surface of the fiber cross section is dissolved. Therefore, in order to completely dissolve and remove the island component, the sea component is also partially dissolved and the fiber is reduced, resulting in fiber thickness deterioration due to thick spots of hardly soluble polymer and solvent erosion. At the same time, fluff and fibrils are produced, and the quality of the product using the fibers may be lowered, which is not preferable.

[Slightly soluble polymer]
The hardly soluble polymer used for the sea component of the sea-island type composite fiber used for obtaining the porous hollow fiber of the present invention is a polymer that is not easily dissolved in an alkaline aqueous solution. The poorly soluble polymer may be any polymer that satisfies the above dissolution rate ratio with the easily soluble polymer used in combination as an island component in the sea-island composite fiber. In order to form a large number of hollow portions uniformly in the direction and the cross-sectional direction of the yarn, it contains a micropore forming agent. As the fine pore forming agent, a metal salt compound represented by the following general formula is used in the present invention.

上記一般式において、Ｍ およびＭ ′は、好ましくはアルカリ金属、アルカリ土類金属、マンガン、コバルト、亜鉛である。

In the above general formula, M 1 and M ′ are preferably alkali metals, alkaline earth metals, manganese, cobalt and zinc.

  As the metal salt compound of this general formula, for example, those described in Japanese Patent Publication No. 61-31231 can be used. Specifically, for example, sodium 3-carbomethoxybenzenesulfonate-5-carboxylate, Mention may be made of sodium 3-hydroxyethoxycarbonylbenzenesulfonate-5-magnesium 1/2 carbonate.

  The metal salt compound may be added to the hardly soluble polymer at any stage before melt spinning. For example, the metal salt compound may be added to the polymerization raw material of the hardly soluble polymer or may be added during the polymerization.

  The content of the metal salt compound in the hardly soluble polymer is 0.1 to 3.0% by weight, preferably 0.5 to 1.5% by weight, per 100% by weight of the hardly soluble polymer. This metal salt compound has an action of forming fine pores on the fiber surface of the sea component at the same time when the island component is dissolved and removed from the sea-island type composite fiber. By containing in this range, especially in long fibers, the solvent for removing the island component is infiltrated in the yarn length direction and the yarn cross-sectional direction, the island component is uniformly removed, and many hollow portions are formed. Can do.

[Sea-island type composite fiber]
The present invention is also a sea-island type composite fiber. That is, the present invention also provides a sea-island type composite fiber having an easily soluble polymer as an island component and a hardly soluble polymer as a sea component, and is observed in a fiber cross section perpendicular to the fiber length direction of the composite fiber. The number of island components is 100 or more, the interval between adjacent island components is 100 nm or more, and the diameter of each island component is in the range of 10 to 1000 nm. It is a composite fiber.

  This sea-island type composite fiber can be used to obtain the porous hollow fiber. In this sea-island type composite fiber, the number of island components needs to be 100 or more, preferably 500 or more. When the number is less than 100, the number of island components of the porous hollow fiber obtained from the sea-island composite fiber is also less than 100, and sufficient performance cannot be obtained with respect to the lightness, heat retention and soft feeling of the porous hollow fiber. If the number of island components is too large, the manufacturing cost of the spinneret increases, and the processing accuracy of the spinneret itself tends to decrease. Therefore, the number of island components is preferably 1000 or less.

  In the sea-island type composite fiber, the interval between adjacent island components is 100 nm or more, preferably 200 nm or more. In the porous hollow fiber obtained when the interval is less than 100 nm, the interval between the adjacent island components is also less than 100 nm, and the mechanical strength of the porous hollow fiber obtained after dissolving and removing the island components cannot be sufficiently ensured.

  Each of the island components has a diameter of 10 to 1000 nm, preferably 100 to 700 nm. When the diameter of the island component is less than 10 nm, the porous hollow fiber structure itself obtained from the sea-island type composite fiber is unstable and the hollow forming property becomes unstable. When the diameter exceeds 1000 nm, the heat retention characteristic of the porous hollow fiber is obtained. Absent. In addition, the quality of a fiber improves, so that the diameter of the hollow part of a porous hollow fiber is uniform.

  The mass ratio of the sea component to the island component (sea component: island component) is preferably 30:70 to 80:20, and more preferably 40:60 to 70:30. Within this range, it is easy to dissolve and remove the island component when obtaining the porous hollow fiber, and it is possible to obtain a porous hollow fiber having sufficient mechanical strength that can withstand practical use after the island component is dissolved and removed. .

From the viewpoint of obtaining a porous hollow fiber having mechanical strength that can withstand practical use in a fiber cross section perpendicular to the fiber length direction, the sea-island type composite fiber passes through the center of the island component diameter (r) and the fiber cross section. When four straight lines are drawn at an angular interval of 45 degrees from each other, the minimum value (S _min ) of the island component spacing on the four straight lines, and the fiber diameter (R) and the island component spacing It is preferable that the maximum value (S _max ) satisfies the relationship of the following formulas (I) and (II).
0.001 ≦ S _min /r≦1.0 (I)
S _max /R≦0.15 (II)
It is more preferable that these satisfy the following formulas (III) and (IV).
0.01 ≦ S _min /r≦0.7 (III)
S _max /R≦0.08 (IV)

  If these conditions are satisfied, it is possible to maintain good high-speed spinnability when producing sea-island type composite fibers, increase the draw ratio, obtain high mechanical strength and adhere to each other adjacent island components. Can be prevented.

  In the measurement of the interval between island components, when the central part of the sea-island type composite fiber is formed by the sea component, the interval between the adjacent island components is excluded from the measurement through the sea component of the central part. To do.

[Production method of sea-island type composite fiber]
The sea-island type composite fiber of the present invention can be produced, for example, by the following method.

  First, an easily soluble polymer and a hardly soluble polymer are melt-spun so that the former is an island component and the latter is a sea component. As a spinneret used for melt spinning, a spinneret having a hollow pin group or a fine hole group for forming an island component can be used. Specifically, for example, an island component flow pushed out from a hollow pin or a fine hole and a sea component flow supplied from a channel designed to fill the gap are merged, and the combined flow is gradually narrowed. However, a spinneret that is extruded from the discharge port to form a sea-island type composite fiber is used.

  An example of a spinneret that is preferably used is shown in FIGS. FIG. 1 is a cross-sectional explanatory view of a part of a spinneret used for spinning the sea-island type composite fiber of the present invention. FIG. 2 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.

  In the spinneret 1 shown in FIG. 1, the island component polymer (melt) in the pre-distribution island component polymer reservoir 2 is distributed in the island component polymer introduction path 3 formed by a plurality of hollow pins. Is done. On the other hand, the sea component polymer (melt) 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 path 3 passes through the sea component polymer reservoir 5 and is located at the center of the inlet of each of the plurality of core-sheath type composite flow passages 6 formed thereunder. The part opens downward.

  From the lower end of the island component polymer introduction path 3, the island component polymer flow is introduced 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 formed as a core-sheath type. An island component polymer flow is introduced into the composite flow passage 6 so as to form a core-sheath type composite flow having the island component polymer flow as a core and a sea component polymer flow as a sheath. It introduce | transduces in the funnel-shaped confluence | merging channel | path 7, In this confluence | merging channel | path 7, a plurality of core-sheath type | mold composite flows mutually join each sheath part, and a sea-island type | mold compound flow is formed. This 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 by an island component polymer introduction passage 13 composed of a plurality of through holes. The melt of island component polymer in the polymer reservoir 2 is distributed into a plurality of island component polymer introduction passages 13, through which it is introduced into the sea component polymer reservoir 5, and the introduced island component polymer stream is Then, it penetrates the sea component polymer (melt) accommodated in the sea component polymer reservoir 5, 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 type composite flow passage 6 so as to surround the island component polymer flow 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 flow down into the funnel-shaped join passage 7, and the sea-island type composite flow is made in the same manner as the spinneret of FIG. It is formed and flows down while reducing its horizontal cross-sectional area, and is discharged through the discharge port 8.

  The sea-island cross-section composite fiber discharged from the spinneret is solidified by cooling air, and wound at a speed of preferably 400 to 6000 m / min, more preferably 1000 to 3500 m / min, to obtain an unstretched sea-island composite fiber. When the spinning speed is 400 m / min or less, the productivity is insufficient and is not preferable. On the other hand, when the spinning speed is 6000 m / min or more, the spinning stability is unfavorable.

  Therefore, the present invention is a process for melting and extruding an island component composed of a readily soluble polymer and a sea component composed of a hardly soluble polymer from a spinneret for sea island type composite fiber in order to produce a sea island type composite fiber. And a method of drawing the extruded sea-island type composite fiber at a spinning speed of 400 to 6000 m / min in this order.

  The obtained unstretched sea-island type composite fiber is made into a stretched sea-island type composite fiber having a desired tensile strength, cutting elongation and heat shrinkage property through a separate stretching process, or is fixed without being wound once. The film is taken up by a roller at a speed, and subsequently wound through a drawing process to obtain a drawn sea-island type composite fiber.

  The stretching process will be specifically described. For example, the sea-island type composite fiber is preheated on a preheating roller having a temperature of 60 to 190 ° C., preferably 75 to 180 ° C., for example, 1.2 to 6.0 times, preferably 2 Stretch at a draw ratio of 0.0 to 5.0 times. In this case, it is preferable to perform heat setting, for example, heat setting is performed with a setting roller having a temperature of 120 to 220 ° C, preferably 130 to 200 ° C.

In the case where the preheating temperature is insufficient, the desired high-magnification stretching cannot be achieved. Moreover, when the heat setting temperature is too low, the contraction rate of the obtained drawn fiber is too high, which is not preferable. On the other hand, if the heat setting temperature is too high, the physical properties of the obtained drawn fiber are remarkably lowered.
In this way, the sea-island type composite fiber of the present invention can be obtained.

  FIG. 3 is a cross-sectional explanatory view of an example of the sea-island composite fiber of the present invention. It is composed of a sea component 22 that forms a matrix and a number of island components 23 that are spaced apart from each other.

  In order to measure the distance between island components in the sea-island type composite fiber of the present invention, four straight lines 25- are passed through the center 24 of the cross section 21 of FIG. 1, 25-2, 25-3, and 25-4 are subtracted to measure the interval between the island components on the four straight lines, and the maximum interval Smax and the minimum interval Smin are determined from them, and the average value Save of the island component intervals Is calculated. In FIG. 3, island components on the four straight lines are mainly described, and thus other island components are not illustrated in FIG. 3.

[Method for producing porous hollow fiber]
The porous hollow fiber of the present invention can be obtained by carrying out a weight reduction treatment by dissolving and removing island components from the sea-island type composite fiber. For example, the island component can be dissolved and removed by immersing in an aqueous sodium hydroxide solution. The concentration of the aqueous sodium hydroxide solution is, for example, 1 to 10% by weight, preferably 2 to 6% by weight. The temperature when the sea-island type composite fiber is immersed in this is, for example, 60 to 97 ° C, preferably 80 to 95 ° C.

  The invention is further illustrated by the following examples. Measurement and evaluation were performed by the following methods.

(1) Melt viscosity The test polymer is dried, set in an orifice set at the melting temperature of an extruder for melt spinning, held in a molten state for 5 minutes, and then extruded under a predetermined level of load. The shear rate and melt viscosity were plotted. The above operation was repeated under multiple levels of load. Based on the above data, a shear rate-one melt viscosity relationship curve was prepared. On this curve, the melt viscosity at a shear rate of 1000 sec- ¹ was estimated.

(2) Dissolution rate ratio Each of the sea component polymer and the island component polymer is extruded through a spinneret for the production of sea-island type composite fibers having 10 holes 0.3 mm in diameter and 0.6 mm in land length (hereinafter referred to as “spinner”). , “Melt spinning step”), and wound at a speed of 1000 to 2000 m / min. This fiber was drawn and controlled so that the elongation at break was in the range of 30 to 60% to produce a multifilament of 50 dtex / 10f. Cylinder knitting was made using this multifilament. The tubular knitting was immersed in a liquid temperature of 95 ° C. in a 4 wt% NaOH aqueous solution, and the weight loss rate ratio (dissolution rate ratio) was calculated from the dissolution time and the dissolution amount at this time. When the dissolution rate ratio of the island component polymer to the sea component polymer in the sea-island composite fiber was 200 or more, it was evaluated as “good”, and when it was less than 200, it was evaluated as “bad”.

(3) Spinnability In the melt spinning step of (2), the case where continuous operation was possible for 7 hours or more was evaluated as “good”, and the other cases were evaluated as “bad”.

(4) Thread properties A tubular knitted fabric having a mass of 1 g or more was produced using sea-island composite fibers. This knitted fabric was immersed in a 4 wt% NaOH aqueous solution at a temperature of 95 ° C. to remove island components. The tube was unwound to obtain a fiber bundle. A load-elongation curve chart of the obtained fiber bundle was prepared under the conditions of an initial sample length of 100 mm and a tensile speed of 200 m / min at room temperature. From this chart, the tensile strength (cN / dtex) and the breaking elongation (%) of the fiber bundle were determined. “Good” when the tensile strength is 1.5 cN / dtex or more and the breaking elongation is 15% or more, and “bad” when the tensile strength is less than 1.5 cN / dtex or the breaking elongation is less than 15%. Was determined.

(5) Intrinsic viscosity Measured at 35 ° C. using orthochlorophenol as a solvent.

(6) Cross section observation of yarn The test fiber was cut so that a cross section perpendicular to the length direction was obtained, and the cross section was photographed at a magnification of 30000 using a transmission electron microscope TEM. Using this electron micrograph, the diameter R of the composite fiber and the diameter r of the island component were measured. In the electron micrograph, draw four straight lines passing through the center point of the composite fiber and intersecting each other at an angle of 45 degrees, and measuring the maximum distance S _min and the maximum distance S _max between the island components on the straight line, The average interval S _ave between the island components was calculated.

(7) Variation in diameter of porous hollow part (CV value)
The island component was removed from the sea-island type composite fiber using a solvent, and the resulting porous hollow fiber bundle was observed with a transmission electron microscope (TEM) at a magnification of 30000 times to measure the diameter of the porous hollow part. The standard deviation (σ) and the hollow portion average diameter (r) were calculated, and the variation (CV value) was calculated by the following equation.
CV value = (standard deviation σ / hollow part average diameter r) × 100 (%)
The hollow portion average diameter (r) is an average value of the major axis and the minor axis of the hollow part measured by observing a cross section of the hollow fiber at a magnification of 30000 using a TEM.

(8) Uniformity of porous hollow fiber The test sea island type composite fiber was treated with an island component solvent, and when the mass reduction corresponding to the island component content ratio was observed, the dissolution treatment was stopped, and the resulting fiber bundle The cross section was observed with a TEM, and the uniformity of the hollow portion was evaluated as “uniform” and “non-uniform” based on the uniformity of the cross section of the single fiber.

(9) Weight reduction rate (%)
The basis weight (g / m ² ) and fabric thickness (mm) of a tubular knitted fabric using 10 filaments of polyester fiber 56 dtex composed of a normal solid section were measured, and a basis curve of fabric weight with respect to the fabric thickness was created. . The reduction rate of basis weight at the same thickness value of the reference curve when the same tubular knitted fabric was produced was defined as the weight reduction rate (%).

(10) Fabric heat retention property In a constant temperature and humidity environment with a temperature of 20 ° C. and a humidity of 60% RH, a 200 W reflex lamp light source is used as an energy source, and light is irradiated from a height of 50 cm. Measured in pairs. The case where this temperature was 30 degreeC or more was determined to be favorable, and the case where it was less than 30 degrees was determined to be defective.

(11) Raw materials Table 1 shows the raw materials used for producing the sea-island type composite fibers. The polymers described in Table 1 are as follows.
PET1:
Polyethylene terephthalate Ny-6 having a melt viscosity at 280 ° C. of 120 Pa · s:
Nylon 6 having a melt viscosity at 280 ° C. of 140 Pa · s
Modified PET1:
197 parts of dimethyl terephthalate, 124 parts of ethylene glycol, 3 parts of 3-carbomethoxy-benzenesulfonic acid Na-5-carboxylate (1.3 mol% with respect to dimethyl terephthalate), 0.118 part of calcium acetate monohydrate Is placed in a glass flask with a rectifying column and subjected to a transesterification according to a conventional method. After the theoretical amount of methanol is distilled off, the reaction product is put into a flask for polycondensation with a rectifying column, and trimethyl phosphate 0. 112 parts and 0.079 parts of antimony oxide as a polycondensation catalyst were added and reacted at a temperature of 280 ° C. under normal pressure for 20 minutes and under reduced pressure of 30 mmHg for 15 minutes, and then reacted under high vacuum for 80 minutes. The final internal pressure was 0.38 mmHg. The polymer obtained by this reaction had an intrinsic viscosity of 0.640 and a softening point of 258 ° C. The polymer was pelletized according to a conventional method.
Modified PET2:
In accordance with the production of the above modified PET1, 4 wt% polyethylene glycol (PEG) having an average molecular weight of 4000 having a melt viscosity of 1600 poise (160 Pa · s) at 285 ° C. and 8 mol% of 5-sodium sulfoisophthalic acid are combined. Polymerized copolymer polyethylene terephthalate was produced.

Example 1
Sea-island composite fibers were produced using the island component polymer and the sea component polymer shown in Table 1. In Example 1, the modified PET1 and the modified PET2 were used as a sea component polymer and an island component polymer in a weight ratio of 50:50, respectively, and both were heated and melted to form a sea island type composite fiber spinning base. Extruded at a spinning temperature of 290 ° C. and wound on a winding roller at the take-up speed shown in Table 1. The obtained unstretched fiber bundle was subjected to roller stretching, and the stretched fiber bundle was subjected to a heat treatment at a temperature of 150 ° C. and wound up. At this time, the spinning discharge flow rate and the draw ratio were adjusted so that the yarn count of the obtained fiber bundle subjected to the drawing heat treatment was 50 dtex / 10f.

Table 1 shows the results of measurement and evaluation of the obtained sea-island type composite fibers. The obtained sea-island type composite fiber had a thin sea component between the island component and the island component, and formed an island having a uniform diameter. The cross-section of this sea-island type composite fiber is observed with a TEM, and the minimum value (S _min ) of the island component diameter (r) and the island component interval, and the maximum value of the sea-island type composite fiber diameter (R) and the island component interval When the relationship of (S _max ) was examined, S _min /r=0.49 and S _max /R=0.1.

  Using this sea-island type composite fiber, a tubular knitting was prepared, immersed in a 4 wt% NaOH aqueous solution at a temperature of 95 ° C., and reduced by 50 wt% until the weight was reduced to 50 wt%. Observation of the cross section of the fiber bundle constituting the tubular knitted fabric after the weight loss treatment revealed that a porous hollow fiber having a uniform porous hollow was formed. The tensile strength of the fiber bundle after the weight reduction treatment was 2.5 cN / dtex, and the elongation at break was 45%.

Example 2
Sea-island type composite fibers were produced in the same manner as in Example 1. However, in Example 2, the same sea component polymer and island component polymer as in Example 1 were used, and both were used in a weight ratio of 60:40. Cylinder knitting was made in the same manner as in Example 1 and immersed in a 4 wt% NaOH aqueous solution at a temperature of 95 ° C, and the weight reduction treatment was performed until the fiber weight of the sea-island type composite fiber was reduced by 40 wt% to 60 wt% Did. When the cross section of the sea-island composite fiber after the weight reduction treatment was observed, a porous hollow fiber having a uniform porous hollow was formed. The tensile strength of the fiber bundle of the obtained porous hollow fiber was 3.0 cN / dtex, and the elongation at break was 35%.

Example 3
Sea-island type composite fibers were produced in the same manner as in Example 1. However, in Example 3, the same sea component polymer and island component polymer as in Example 1 were used, and both were used in a weight ratio of 80:20. When the cross section of the sea-island type composite fiber was observed, the sea component between the island component and the inter-island component was thin, and an island having a uniform diameter was formed. The cross section of the sea-island composite fiber is observed with a TEM, and the minimum value S _min of the island component diameter (r) and the island component interval, and the maximum value S _{max of the} sea-island composite fiber diameter (R) and the island component interval. As a result, S _min /r=0.30 and S _max /R=0.01.

  Using the obtained drawn yarn, a cylindrical knitting was made in the same manner as in Example 1, and the sea-island type composite fiber was reduced by 20% by weight to 80% by weight by immersing in a liquid temperature of 95 ° C. in a 4% by weight NaOH aqueous solution. Reduced weight until it was. When a cross section of the obtained fiber bundle was observed, fibers having a uniform porous hollow were formed. Spinning was performed so that the tensile strength of the fiber bundle after removal of the island component was 3.5 cN / dtex, the elongation at break was 50%, and the yarn count of the resulting heat-treated fiber bundle was 50 dtex / 10f. The discharge flow rate and the draw ratio were adjusted.

Examples 4 and 5
Sea-island type composite fibers were produced in the same manner as in Example 1. In Examples 4 and 5, the same sea component polymer and island component polymer as in Example 2 were used, the weight ratio of both was 60:40, and the number of islands and the island diameter were as shown in Table 1. Yarn was made with a die. The sea-island type composite fiber obtained had good cross-sectional formability.

  In the production of the porous hollow fiber, the same method as in Example 1 was used, and the weight reduction treatment was performed until the sea-island type composite fiber was reduced by 40% by weight to 60% by weight. The spinning discharge flow rate and the draw ratio were adjusted so that the yarn count of the obtained fiber bundle subjected to the drawing heat treatment was 50 dtex / 10f.

Examples 6-8
Sea-island type composite fibers were produced in the same manner as in Example 1. In Examples 6 and 7, the same sea component polymer and island component polymer as in Example 2 were used, the weight ratio of both was 60:40, and the number of islands and the diameter of the islands were as shown in Table 1. Made in The sea-island type composite fiber obtained had good cross-sectional formability.

Comparative Example 1
Sea-island type composite fibers were produced in the same manner as in Example 1. In Comparative Example 1, the same sea component polymer and island component polymer as in Example 1 were used, and both were spun and stretched with a weight ratio of 20:80 and an island number of 800. Although the cross-section formability of the obtained sea-island type composite fiber was good, since the sea component amount is too small, the thickness of the sea component between islands and islands is thin, and after elution of the island components by weight reduction treatment with an alkaline aqueous solution The strength of the resulting porous hollow fiber was weak and could not withstand practical use.

Comparative Example 2
Sea-island type composite fibers were produced in the same manner as in Example 1. In Comparative Example 2, the same sea component polymer and island component polymer as in Example 1 were used, and both were spun and stretched at a weight ratio of 90:10 and an island number of 800. The sea-island type composite fiber obtained had good cross-sectional formability, but because the amount of sea component was too large, the sea component thickness between islands and islands was so thick that the island component at the center of the fiber could not be dissolved and removed, The hollow was not formed uniformly.

Comparative Example 3
Sea-island type composite fibers were produced in the same manner as in Example 1. In Comparative Example 3, modified PET1 was used as a sea component polymer and PET1 was used as an island component polymer at a weight ratio of 60:40. Although the formation of sea islands was good, the rate of weight loss by the alkaline aqueous solution of the island component was insufficient compared to that of the sea component, so a considerable amount of the polymer for the sea component was reduced during the alkali weight reduction. Even though a considerable amount of the sea component polymer has been removed, the majority of the island component polymer distributed in the central portion of the composite fiber remains unreduced and is a uniform porous hollow fiber. Was not obtained.

Comparative Example 4
Sea-island type composite fibers were produced in the same manner as in Example 1. In Comparative Example 4, PET1 was used as the sea component polymer, and modified PET2 was used as the island component polymer at a weight ratio of 60:40. Sea-island formation was good, but the sea component polymer does not contain a micropore-forming agent, so even if a significant amount of sea component is reduced, a considerable amount of island component is not completely removed, It remained in the central part of the composite fiber, and a uniform porous hollow fiber could not be obtained.

  According to the porous hollow fiber of the present invention, a porous hollow fiber is uniformly formed in a single fiber, and it is possible to provide a polyester-based hollow fiber that achieves both lightness and heat retention.

  Further, the sea-island type composite fiber of the present invention can easily dissolve and remove the island component, so that a porous hollow can be uniformly formed in a single fiber, and is used for producing a polyester-based hollow fiber excellent in lightness and heat retention. be able to.

1 Spinneret 2 Pre-distribution island component polymer reservoir 3 Island component polymer introduction path 4 formed by a plurality of hollow pins 4 Sea component polymer introduction channel 5 Pre-distribution sea component polymer reservoir 6 Multiple core-sheath type composite flow Passage 7 funnel-like joining passage 8 discharge port 11 spinneret 13 introduction passage 21 for island component polymer composed of a plurality of through-holes 21 cross-sectional explanatory view of an example of sea-island type composite fiber 22 sea component 23 forming a matrix separated from each other A large number of island components 24 arranged at the center of the spinneret cross section 25 A straight line passing through the center of the spinneret cross section and having an angular interval of 45 degrees from each other

Claims (7)

A porous hollow fiber obtained by removing the island component from a plurality of sea-island type composite fibers having an easily soluble polymer as an island component and a hardly soluble polymer as a sea component, The number of hollow portions observed in a cross section perpendicular to the fiber is 100 or more per porous hollow fiber, the interval between adjacent hollow portions is 100 nm or more, and the diameter of each hollow portion is 10 to 1000 nm. The variation in the diameter of the hollow part (CV value) is 30% or less, the hardly soluble polymer contains a metal salt compound represented by the following formula, and the content thereof is a hardly soluble polymer. A porous hollow fiber characterized by being 0.1 to 3.0% by weight per 100% by weight.

  The easily soluble polymer is at least one selected from the group consisting of polylactic acid, ultrahigh molecular weight polyalkylene oxide condensation polymer, polyethylene glycol compound copolymer polyester, and copolymer polyester of polyethylene glycol compound and 5-sodium sulfoisophthalic acid. The porous hollow fiber according to claim 1, which is a seed.   The porous hollow fiber according to claim 1, wherein the number of hollow portions is 500 or more per porous hollow fiber. A sea-island type composite fiber having an easily soluble polymer as an island component and a hardly soluble polymer as a sea component, and the number of island components observed in a fiber cross section perpendicular to the fiber length direction of the composite fiber is 100 or more, the interval between adjacent island components is 100 nm or more, the diameter of each island component is in the range of 10 to 1000 nm, and the variation in the diameter of the hollow portion (CV value) is 30% or less And the hardly soluble polymer contains a metal salt compound represented by the following formula, and the content thereof is 0.1 to 3.0% by weight per 100% by weight of the hardly soluble polymer. Sea-island type composite fiber.

  The sea-island type composite fiber according to claim 4, which is used for producing a porous hollow fiber.   The sea-island type composite fiber according to claim 4, wherein a mass ratio of the sea component to the island component (sea: island) is 30:70 to 80:20.   The sea-island type composite fiber according to claim 4, wherein a dissolution rate ratio (island / sea) of the island component to the sea component is 200 or more.

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