JP2011069023A - Conjugate fiber having pores, and method for producing the same - Google Patents

Abstract

The present invention provides a composite fiber capable of expressing characteristics such as heat retention, water absorption, soft feeling, light weight, and swell, and a fiber structure including the fiber.
Two types of thermoplastic resins form a core-sheath structure in the fiber axis direction, and are composite fibers having pores 1 continuous in the fiber axis direction inside the core component, the core component 2 Is a thermoplastic resin (X), an ethylene-vinyl alcohol polymer resin (Y) having a content of ethylene units of 15 mol% or more that has wet heat adhesion of the sheath component 3 but is not hot water soluble, A composite fiber having a weight ratio (X) / (Y) of both resins of 80/20 to 20/80, a porosity of 5 to 30% per fiber cross-sectional area, and a fiber structure including the fiber.
[Selection] Figure 1

Description

  The present invention relates to a composite fiber having pores and a method for producing the same.

With recent changes in lifestyle, the demands for heat retention, water absorption, soft feeling, light weight, swell, etc. have been attracting attention. It is expected to be developed for various uses such as walls, flooring materials, and carpet bottom materials. In the conventional fiber material, in order to express the characteristics as described above, it is widely performed to form a composite fiber using a polymer such as polyester or polyamide and to provide pores in the fiber. The effect was not enough.
Furthermore, by having pores in the composite fiber of the ethylene-vinyl alcohol copolymer having excellent characteristics of heat retention, water absorption, and softness, it is possible to produce fibers with excellent lightness and swell. Although examined, ethylene-vinyl alcohol-based polymers are inferior in spinnability compared to other fiber-forming polymers, and thus have not led to the production of fibers having the above-mentioned swelled and good texture.

  As a method for producing a fiber having pores in a composite fiber for the purpose of imparting characteristics such as heat retention, water absorption, soft feeling, light weight, and swelling, a core is a polyester resin, and a sheath is ethylene -The core-sheath type composite fiber made of vinyl alcohol copolymer resin is subjected to alkali weight loss treatment, and a part of the polyester polymer in the core part (boundary surface part with the sheath part) is decomposed and removed so that pores are expressed. A method is described (for example, see Patent Document 1). However, in the production method described in Patent Document 1, it is difficult to reduce the amount uniformly in the fiber length direction, and the weight loss part becomes non-uniform, and the physical properties and color tone are likely to be uneven. There are problems such as the possibility that the residue may adversely affect the physical properties. In particular, the joint between the core and the sheath disappeared due to the alkali weight loss treatment (the disappeared part is a void), and the sheath and the core were peeled off. As a result, the inner pores are easily crushed, and the sheath has a wet-heat adhesive property, so the sheath and the core are bonded to each other when heat is applied. There was a problem that the structural shape could not be maintained. In addition, as a problem at the time of production, there is an alkali weight reduction process, which makes the process complicated or requires equipment for processing the extracted waste liquid. It was also necessary to consider the impact on the environment.

  Moreover, as an example of the use using the ethylene-vinyl alcohol copolymer fiber which is a wet heat bonding fiber, it is disclosed in the use of a non-woven fabric, and the purpose is to obtain a non-woven fabric having high bulkiness, high flexibility and sufficient strength. In addition, there is a report on a non-woven fabric application in which the ethylene-vinyl alcohol copolymer portion of the fiber is wet-heat bonded (the fiber surface is melt-fixed by contacting with high-temperature steam) (see, for example, Patent Document 2). . However, although these nonwoven fabrics have excellent characteristics in terms of bulkiness, flexibility, water absorption, and soft feeling, they have not been sufficiently effective in terms of heat retention and light weight.

JP-A-5-106118 International Publication No. 2007/116676 Pamphlet

The objective of this invention is providing the fiber structure containing the composite fiber which can express characteristics, such as heat retention, water absorption, soft feeling, lightness, and a swelling feeling.
Furthermore, an object of the present invention is to provide a production method in which a nonwoven fabric structure can be easily obtained by wet-heat bonding (melting and fixing the fiber surface by bringing it into contact with high-temperature steam) from the composite fiber. It is in.

  As a result of intensive investigations on fibers having heat retention, water absorption, soft feeling, light weight, swell feeling, etc., the present inventors constituted the core component with the thermoplastic resin (X), while the sheath component is wet-heat bonded. And a hot-water-soluble ethylene-vinyl alcohol polymer resin (Y), and after melt extrusion of the resins (X) and (Y) at a weight ratio within a predetermined range, a known hollow spinning nozzle The present invention has been achieved by producing a composite fiber having continuous pores in the fiber axis direction inside the core component immediately after spinning from the nozzle.

  That is, the present invention is a composite fiber having a core-sheath structure in the fiber axis direction and having pores continuous in the fiber axis direction inside the core component, the core component being a thermoplastic resin (X), The sheath component is an ethylene-vinyl alcohol polymer resin (Y) having an ethylene unit content of 15 mol% or more that has wet heat adhesiveness but is not hot water soluble, and the weight ratio (X) between the two resins. / (Y) is a composite fiber having 80/20 to 20/80 and a porosity per fiber cross-sectional area of 5 to 30%.

  Further, the present invention is preferably the above-described composite fiber wherein the thermoplastic resin (X) has a melt viscosity at 290 ° C. of 2000 to 12000 [Pa · s], more preferably a fiber structure containing the composite fiber. It is about.

  The present invention provides an ethylene-vinyl alcohol-based polymer resin having a thermoplastic resin (X) as a core component and an ethylene unit content of 15 mol% or more that has wet heat adhesiveness but is not hot water soluble in a sheath component. (Y) is used to melt-extrude the resin in a weight ratio of (X) / (Y) = 80/20 to 20/80, and then spin with a hollow spinning nozzle, so that the fibers inside the core component The present invention relates to a method for producing a composite fiber, characterized in that pores continuous in the axial direction are generated.

According to the present invention, a nonwoven fabric structure can be easily obtained from a composite fiber having the above-described structure by a production method by wet heat bonding (the fiber surface is melted and fixed by being brought into contact with high-temperature steam).
Furthermore, the fiber structure containing the conjugate fiber of the present invention can exhibit characteristics such as heat retention, water absorption, soft feeling, light weight, and swell feeling.

Hereinafter, the present invention will be described in detail. The composite fiber of the present invention is characterized in that it has pores inside the core component, and the pores are continuously present along the fiber axis direction of the fiber.
Such a composite fiber of the present invention is composed of a core component made of a thermoplastic resin (X) and a sheath component made of a resin (Y) that has wet heat adhesiveness but is not hot water soluble, The weight ratio (X) / (Y) between (X) and (Y) needs to be 80/20 to 20/80.
If the weight ratio (X) / (Y) is outside the above range, the sheath part is broken and the shape of the fiber cross-section is apt to be broken, such as hole collapse in the core part, and desired performance can be expressed in the resulting composite fiber. It can be difficult. In order to prevent poor shape of the fiber cross section, the (X) / (Y) ratio is preferably 70/30 to 30/70, more preferably 60/40 to 40/60.

Examples of the thermoplastic resin (X) constituting the core component include cellulose resins (C _1-3 alkyl cellulose ether, hydroxy C _1-3 alkyl cellulose ether, carboxy C _1-3 alkyl cellulose ether, or salts thereof). , Polyalkylene glycol resins (polyethylene oxide, polypropylene oxide, etc.), polyvinyl resins (polyvinyl pyrrolidone, polyvinyl ether, polyvinyl acetal, etc.), acrylic copolymers and alkali metal salts thereof, modified vinyl copolymers, polyolefin resins (Meth) acrylic resin, vinyl chloride resin, styrene resin, polyester resin, polyamide resin, polycarbonate resin, polyurethane resin, thermoplastic elastomer and the like. Particularly preferred are polyolefin resins, polyester resins and polyamide resins.

  Examples of the polyolefin resin include polymers such as polypropylene, polymethylpentene, polyethylene, polybutene, and copolymers thereof. In particular, it is preferable to use a polyolefin resin having a melting point of 130 ° C. or higher, more preferably 150 ° C. or higher because of excellent heat resistance.

  As a polyester-type resin, the structural unit induced | guided | derived from the bifunctional compound as an acid unit and a glycol unit may contain the 1 type (s) or 2 or more types as a copolymer unit as needed. Such structural units derived from other bifunctional compounds include terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, biphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid and the like. Aromatic dicarboxylic acids; Aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid and dodecanedioic acid; alicyclic dicarboxylic acids such as decalin dicarboxylic acid and cyclohexanedicarboxylic acid; glycolic acid , Hydroxy carboxylic acids such as hydroxybenzoic acid, mandelic acid, matrolactic acid; aliphatic lactones such as ε-caprolactone; ethylene glycol, trimethylene glycol, tetramethylene glycol, 1,5-pentanediol , 1,6-hexanediol, neopentyl glycol, diethylene glycol, polyethylene glycol, polybutylene glycol and other aliphatic diols; hydroxylene, catechol, naphthalenediol, resorcin, 1,4-bis (β-oxyentoxy) benzene, etc. Aromatic diols; structural units derived from bifunctional components such as cycloaliphatic diols such as cyclohexanedimethanol.

  Examples of polyamide resins include aliphatic polyamides such as polyamide 6, polyamide 66, polyamide 610, polyamide 10, polyamide 12, polyamide 612, and copolymers thereof, and semi-aromatic compounds synthesized from aromatic dicarboxylic acids and aliphatic diamines. A group polyamide is preferred. These polyamide-based resins may also contain other copolymerizable units.

  The thermoplastic resin (X) preferably has a melt viscosity at 290 ° C. in the range of 2000 to 12000 [Pa · s]. If the melt viscosity is higher than 12000 [Pa · s], the viscosity is too high, and as a result of increasing the nozzle pressure, the nozzle may be damaged. On the other hand, when the melt viscosity is 2000 [Pa · s] or less, the viscosity is too low, so that it is difficult to form a filament and the spinnability of the composite fiber may be deteriorated. It is more preferable that the melt viscosity is in the range of 10,000 to 4000 [Pa · s] because troubles such as yarn breakage in the spinning process are reduced and the productivity of the resulting composite fiber is excellent.

  Next, in the ethylene-vinyl alcohol copolymer forming the sheath component, the ethylene unit content (copolymerization ratio) is 15 mol% or more and 60 mol% or less, preferably 20 to 55 mol%, more preferably. 30 to 50 mol%. When the ethylene unit is in this range, a unique property of having wet heat adhesiveness but not hot water solubility is obtained in a wider range of hot water temperatures. When the proportion of the ethylene units is less than 15 mol%, the ethylene-vinyl alcohol copolymer easily swells or gels with low-temperature steam (water), and its form is likely to change only once it is wetted with water. On the other hand, when the proportion of ethylene units is more than 60 mol%, the hygroscopicity is lowered, and it becomes difficult to develop fiber fusion due to endotherm, so it is difficult to ensure practical strength. Preferably, the proportion of ethylene units is in the range of 20 to 55 mol%, and further the proportion of ethylene units is in the range of 30 to 50 mol%, since the processability to the nonwoven fabric is excellent.

  The saponification degree of the vinyl alcohol unit in the ethylene-vinyl alcohol copolymer is, for example, about 90 to 99.99 mol%, preferably 95 to 99.98 mol%, more preferably 96 to 99.97 mol%. Degree. When the degree of saponification is too small, the thermal stability is lowered, and the stability is lowered by thermal decomposition or gelation. On the other hand, if the degree of saponification is too large, it is difficult to produce the fiber itself.

Although the viscosity average degree of polymerization of an ethylene-vinyl alcohol-type copolymer can be selected as needed, it is 200-2500, for example, Preferably it is 300-2000, More preferably, it is about 400-1500. When the degree of polymerization is within this range, the balance between spinnability and wet heat adhesion is excellent.
Further, the melt index value (MI value) of the ethylene-vinyl alcohol copolymer is preferably in the range of 3-30. In addition, MI value is measured by the method mentioned later.

  The composite fiber of the present invention is characterized in that, as described above, the core component has pores, and the pores are continuous along the fiber axis direction of the fiber. The shape of the hole is not particularly limited, and may be a circular shape, an elliptical shape, a polygonal shape, a star shape, or the like, but it is a circular shape in view of the highest area ratio per outer periphery of the hole. It is desirable. Further, the number of holes is not limited to one and may be two or more.

The form of the conjugate fiber of the present invention may be a filament shape which is a long fiber and a short fiber shape having a length of about 1 to 100 mm. Moreover, you may provide crimp as needed.
The fineness of the composite fiber of the present invention can be arbitrarily determined in the range of 0.4 to 50 dtex depending on the application. Preferably, it is 0.7-40 dtex.

  Moreover, as a post-treatment method of the composite fiber of the present invention, heat setting may be performed after performing an unstretched treatment, a wet heat stretch treatment, and a dry heat stretch treatment.

The composite fiber of the present invention needs to have a porosity per fiber cross-sectional area of 5 to 30%. If the porosity is outside the above range, the processability such as spinning and drawing of the composite fiber is likely to deteriorate, and it may be difficult to express the desired performance. Preferably it is 7 to 27%, more preferably 10 to 25%.
In addition, the porosity as used in the field of this invention is computed by the following formula.
<(Hole area) / (Composite fiber area)> × 100
The composite fiber area here is the fiber area including the area of the pores.

The conjugate fiber of the present invention preferably has a core-sheath structure having a cross section as shown in FIG. The position of the core part with respect to the sheath part may be either concentric or eccentric, and the position of the hole with respect to the core part may be either concentric or eccentric.
Furthermore, although the position of the hole with respect to the sheath part may be either concentric or eccentric, the interface between the resin (X) and the resin (Y) and the interface between the resin (X) and the hole should not be in contact with each other. Is desirable.
In addition, the shape of the fiber cross section of the composite fiber itself may be circular, or other various cross sections.

  The composite fiber of the present invention may contain various additives as necessary. For example, metal powder, metal oxides such as silica, alumina and titanium oxide, inorganic particles such as calcium carbonate and barium sulfate, and oxidation. It may contain an inhibitor, an ultraviolet absorber, a flame retardant, a crosslinking agent, a heat-resistant agent, a fluorescent brightening agent, a coloring agent, an antibacterial agent, an fragrance, and the like.

The spinning nozzle used when spinning the conjugate fiber of the present invention may be a known nozzle as long as it has a hollow cross section. Specifically, it is preferable to use a core-sheath hollow spinning nozzle having a hollow ratio of 20 to 90% and supporting at one point. When a nozzle having a hollow ratio of less than 20% is used, the core hole is immediately after melt spinning. May be blocked, and it may be difficult to ensure the fiber cross-sectional shape. On the other hand, if the hollowness exceeds 90%, the cross-sectional shape of the composite fiber will be poor, such as sheath breakage and core hole crushing, or troubles such as yarn breakage will occur frequently and spinning will become extremely difficult. Therefore, it is more preferable to use a nozzle having a hollow ratio of 30 to 80%.
The spinning temperature of the composite fiber is preferably 260 to 310 ° C., and the melt viscosity during spinning is preferably 2000 to 24000 [Pa · s].

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by this Example. In the following examples, the melt viscosity of the thermoplastic resin (X), MI of the thermoplastic resin (Y), fiber fineness, fiber porosity, fiber cross-sectional shape evaluation, and spinnability evaluation were measured by the following methods. Show things.

[Melt viscosity Pa · s of thermoplastic resin (X)]
Using a melt viscometer, after preheating at a temperature of 290 ° C. for 10 minutes, the molten thermoplastic resin was extruded from a nozzle and measured.

[MI g / 10 min of thermoplastic resin (Y)]
A certain amount of synthetic resin (2160g) is heated and pressurized at a specified temperature (190 ° C) in a cylindrical container heated by a heater, and extruded from the opening (nozzle) provided at the bottom of the container every 10 minutes. The amount of resin formed was measured.

[Fiber fineness dtex]
Five sets of 30 single yarn samples cut to 30 mm were prepared, and the weight of each sample was measured twice.
Fineness (dtex) = weight (g) / (number of 30 × fiber length 30 mm) × 10000 m

[Fiber porosity%]
A cross-sectional photograph was taken using a microscope, and the diameter of the hollow portion of the composite fiber = φA and the diameter of the composite fiber = φB were measured from the cross-sectional photograph as shown in FIG. .
Hollow ratio (%) = (φA ² / φB ² ) × 100

[Fiber cross-sectional shape evaluation]
A cross-sectional photograph was taken using a microscope, the cross-sectional shape was observed with the photograph, and the following determination was made.
○: The sheath is not broken, the void portion is not lost or crushed, and the interface between the core portion and the hollow portion is not in contact.
(Triangle | delta): A sheath is torn and a void | hole part is crushed. Alternatively, the interface between the core portion and the hollow portion is in contact.
X: The sheath part or the core part has disappeared. Or vacancies have disappeared.

[Spinnability]
The spinnability was evaluated based on the following criteria. The evaluation of yarn breakage and wrinkling was evaluated as a result of spinning for 4 hours.
○: Can be scraped after spinning from the nozzle, and troubles such as yarn breakage and wrinkling do not occur.
Δ: Can be scraped after spinning from the nozzle, but troubles such as yarn breakage and tacking frequently occur.
X: Cannot be spun from the nozzle, or even if it can be spun, it cannot be wound up and a sample cannot be collected.

[Examples 1 to 3]
Polyethylene chips having an ethylene content of 44 mol% and an MI-value of 12 ethylene-vinyl alcohol copolymer having a sheath component and a core component having a melt viscosity of 12000 [Pa · s] at 290 ° C. (polyethylene terephthalate, intrinsic viscosity = 0. 61), and the polymer ratio is supplied at a ratio of core-sheath ratio = 75/25 (Example 1), 50/50 (Example 2), and 25/75 (Example 3), melt-extruded, and hollow ratio 50 % From the nozzle. As a result of spinning, although the yarn breakage occurred and the spinnability was poor, the porosity was 19% (Example 1), 15% (Example 2), 10% (Example 3) with a good cross-sectional shape, after wet heat stretching treatment A composite hollow fiber having a fineness of 3.3 dtex could be collected. The results are shown in Table 1.

[Examples 4 to 9]
The same ethylene-vinyl alcohol copolymer as in Examples 1 to 3 was used as the sheath component, and the melt viscosity at 290 ° C. was 8000 [Pa · s] (Examples 4 to 6) or 6000 [Pa · s] as the core component. The polyester ratio (polyethylene terephthalate, intrinsic viscosity: 0.51 to 0.57) of (Examples 7 to 9) was used, and the polymer ratio was 75/25 (Examples 4 and 7), 50/50. (Examples 5 and 8), 25/75 (Examples 6 and 9) The ratio was changed to melt extrusion, and spinning was performed from a nozzle having a hollow ratio of 50%. As a result, spinnability was good (breaking during a short test). No trouble occurs in the yarn), and the porosity is 16% (Example 4), 13% (Example 5), 8% (Examples 6 and 7), 6% (Example 8), And 5% (Example 9) of composite hollow fibers could be collected. As a result of wet heat drawing treatment using this raw yarn, fibers having a fineness of 3.2 dtex could be collected. The results are shown in Table 1.

[Examples 10 to 12]
The polymer of the sheath component is the same as in Examples 1 to 3, using a nozzle with a hollow ratio of 40%, and the core component has a melt viscosity at 290 ° C. of 10000 [Pa · s] (Example 10) and 8000 [Pa · s]. (Example 11), polyester chip of 6000 [Pa · s] (Example 12) (polyethylene terephthalate, intrinsic viscosity: 0.55 to 0.59), polymer ratio spun under the condition of core-sheath ratio = 50/50 did. As a result, the porosity decreased, but the fineness after wet heat stretching treatment was 3.3 dtex, and the porosity was 8% (Example 10), 6% (Example 11), and 5% (Example 12), respectively. Composite hollow fibers could be collected. The results are shown in Table 1.

[Examples 13 to 15]
Using a nozzle with a hollow ratio of 50%, an ethylene-vinyl alcohol copolymer having an ethylene content of 32 mol% and an MI value of 5 as the sheath component, and a melt viscosity at 290 ° C. of 12000 [Pa · s] (core component) Example 13), 8000 [Pa · s] (Example 14), 6000 [Pa · s] (Example 15) polyester chips (polyethylene terephthalate, intrinsic viscosity: 0.55 to 0.61) The ratio was spun at a ratio of core / sheath ratio = 50/50. As a result, the sheath was partially broken in the cross-sectional shape (FIG. 4), but the spinnability was good and the porosity was 20% (Example 13), 12% (Example 14), 6% ( The composite hollow fiber of Example 15) could be collected. As a result of wet heat drawing treatment using this raw yarn, fibers having a fineness of 3.2 dtex could be collected. The results are shown in Table 1.

[Examples 16 to 17]
An ethylene-vinyl alcohol copolymer having an ethylene content of 44 mol% and an MI value of 12 is used as a sheath component, and the melt viscosity at 290 ° C. is 11000 [Pa · s] (Example 16) and 6000 [Pa · s] as the core component. ] (Example 17) polypropylene chips ("Y-2005GP" (Example 16) manufactured by Prime Polymer Co., Ltd., "Y-3002G" (Example 17) manufactured by Prime Polymer Co., Ltd.)) The mixture was supplied at a ratio of 50/50, melt-extruded, and spun from a nozzle having a hollow ratio of 50%. As a result, the one having a melt viscosity of 11000 was good (porosity 12%). On the other hand, for the 6000 fiber, a partial sheath breakage occurred in the cross-sectional shape, but a composite hollow fiber having a porosity of 5% could be collected. As a result of wet heat drawing treatment using this raw yarn, fibers having a fineness of 3.2 dtex could be collected. The results are shown in Table 1.

[Comparative Examples 1-2]
An ethylene-vinyl alcohol copolymer having an ethylene content of 44 mol% and an MI value of 12 is used as a sheath component, and the core component is a polyester chip (polyethylene terephthalate, intrinsic viscosity: 0 at 290 ° C. but having a melt viscosity of 8000 [Pa · s]. .57), the core / sheath polymer ratio is supplied at a ratio of core / sheath ratio = 85/15 (Comparative Example 1) and 15/85 (Comparative Example 2), melt-extruded, and from a nozzle having a hollow ratio of 15%. Spinned. As a result, the spinnability was good, but the cross-sectional shape was poor, such as collapse of the pores and tearing of the sheath, and the target raw yarn could not be collected.

[Comparative Examples 3 to 4]
Polyester chip (polyethylene terephthalate, intrinsic viscosity: 0.001) having an ethylene content of 44 mol% and an ethylene-vinyl alcohol copolymer having an MI value of 12 as a sheath and a core component having a melt viscosity at 290 ° C. of 16000 [Pa · s]. 65), the polymer ratio of core / sheath is supplied at a ratio of core / sheath ratio = 85/15 (Comparative Example 3), 15/85 (Comparative Example 4), melt-extruded, and with a nozzle having a hollow ratio of 50%. Spinned. The result was that the melt viscosity was too high, resulting in poor spinnability (many unmelted yarns from the nozzle), and the target raw yarn could not be collected.

[Comparative Examples 5-6]
Polyester chips (polyethylene terephthalate, intrinsic viscosity: 0) having an ethylene content of 44 mol% and an ethylene-vinyl alcohol copolymer having an MI value of 12 as a sheath component and a core component having a melt viscosity of 10000 [Pa · s] at 290 ° C. 59), the polymer ratio of the core / sheath is supplied at a ratio of core / sheath ratio = 85/15 (Comparative Example 5), 15/85 (Comparative Example 6), melt-extruded, and a nozzle having a hollow ratio of 50% And spun. As a result, the spinnability was poor (troubles such as yarn breakage occurred), the cross-sectional shape was also ruptured in the sheath and collapsed the holes, and the target raw yarn could not be collected.

[Comparative Examples 7-8]
Polyester chips (ethylene terephthalate, intrinsic viscosity: 0.57) having an ethylene content of 44 mol% and an MI-value of 12 ethylene-vinyl alcohol copolymer as a sheath component, and a core component having a melt viscosity at 290 ° C. reduced to 8000. ), The core / sheath polymer ratio is supplied at a ratio of core / sheath ratio = 85/15 (Comparative Example 7), 15/85 (Comparative Example 8), melt-extruded, and spun by a nozzle having a hollow ratio of 50%. As a result, the spinnability was improved, but the sheath breakage and void collapse were not improved, the cross-sectional shape was poor, and the target raw yarn could not be collected.

  The composite fiber of the present invention can be used in various applications by taking advantage of the heat retention, water absorption, softness, lightness, swell, etc. of the fiber, such as curtains, wall coverings, flooring, ceilings, etc. It is also suitable for interior interior materials, interior materials for vehicles, etc., and filling products such as hard cotton by using the fibers as the filled cotton. Furthermore, it is preferably used as a fiber constituting a fabric such as a woven fabric, a knitted fabric or a nonwoven fabric as a short fiber or a long fiber.

The schematic diagram which shows an example (example which made the core and the void | hole part concentric with respect to the sheath part) of the cross section of the composite fiber of this invention. The schematic diagram which shows an example (example which made the core and the void | hole part eccentric with respect to the sheath part) of the cross section of the composite fiber of this invention. The schematic diagram which shows the measuring method of the porosity of the composite fiber of this invention. The schematic diagram which shows an example of the cross-sectional shape of the composite fiber in which sheath tearing generate | occur | produced partially in this invention.

1 Hole 2 Core component 3 Sheath component

Claims (4)

  A composite fiber having a core-sheath structure in the fiber axis direction and having pores continuous in the fiber axis direction inside the core component, the core component being thermoplastic resin (X), and the sheath component being wet heat bonded Is an ethylene-vinyl alcohol polymer resin (Y) having an ethylene unit content of not less than hot water solubility but 15 mol% or more, and the weight ratio (X) / (Y) of the two resins is A composite fiber having a porosity of 80/20 to 20/80 and a fiber cross-sectional area of 5 to 30%.   The composite fiber according to claim 1, wherein the thermoplastic resin (X) has a melt viscosity of 2,000 to 12000 [Pa · s] at 290 ° C.   A fiber structure comprising the conjugate fiber according to claim 1.   A thermoplastic resin (X) is used for the core component, and an ethylene-vinyl alcohol polymer resin (Y) containing 15 mol% or more of an ethylene unit that has wet heat adhesiveness but is not hot water soluble is used for the sheath component. The resin was melt-extruded under the condition of the weight ratio of the resin (X) / (Y) = 80/20 to 20/80, and then spun by a hollow spinning nozzle, thereby being continuous in the fiber axis direction inside the core component. A method for producing a composite fiber, characterized by generating pores.

Images