JPH0367122B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Field of Application) The present invention relates to a crimped porous hollow fiber that exhibits highly excellent three-dimensional crimp, excellent bulkiness, bulk recovery, heat retention, and soft feel, and a method for producing the same. More specifically, the present invention relates to crimped porous hollow fibers that exhibit excellent feather-like properties when used in carpets, high piles, moquettes, clothing, etc., and especially in stuffing, and a method for producing the same. (Prior Art) Methods for imparting three-dimensional crimp to fibers by melt spinning have been proposed in the past, but these methods cannot be said to be practically satisfactory. That is, (A) there is a method in which two types of polymers with different contractility are composite-spun into a bimetal type or a core-sheath type in which the core component is eccentric. With this method, the spinning operation is quite difficult and it is difficult to obtain products with stable quality.
Further, it has drawbacks such as a complicated spinning device and high equipment costs. (B) A method of heating one side of the solution-spun yarn to impart anisotropy in the cross-sectional direction, for example (Japanese Patent Publication No. 43-13351
(See Publication No.). With this method, it is difficult to obtain a satisfactory product because fusion occurs between each single fiber during the spinning operation. (C) A method in which a non-uniform structure is created in the cross-sectional direction of the fiber by creating a certain angle between the direction in which the polymer is discharged from the nozzle and the direction in which the discharged yarn is taken (see, for example, Japanese Patent Publication No. 43-27539). There is.
This method has drawbacks such as extremely poor spinning performance and very low operability since the flow state of the polymer at the nozzle outlet is extremely disturbed. (D) A method for obtaining three-dimensional crimped fibers by blowing a cooling air stream onto the yarn immediately after discharge and imparting birefringence anisotropy in the cross-sectional direction (for example, see Japanese Patent Publication No. 7511/1983). However, as an improvement method to this, a method was proposed by Tokuko Sho to further increase the anisotropy by providing a single hollow section at the substantial center or eccentric position of the fiber cross section.
Publication No. 44-20497, Publication No. 45-36330, Publication No. 56-
It is described in Publication No. 29007. Further, JP-A-54-112242 describes a method of rapidly cooling the cross section of a nylon discharged yarn having a substantially rectangular cross-sectional shape and four hollow portions. However, with the crimped fibers obtained by these methods, it is not possible to obtain crimped fibers that exhibit sufficiently satisfactory bulk, bulk recovery, heat retention, and texture, and the range of optimal conditions is very limited. It is narrow and productivity is low. (Objective of the Invention) The present invention has been made against the background of the above circumstances, and its purpose is to provide a highly superior three-dimensional crimp, excellent bulkiness, bulk recovery, and heat retention. An object of the present invention is to provide a crimped porous hollow fiber exhibiting a flexible texture and an industrial method for producing the same. (Structure) As a result of studies to achieve the above object, the inventors of the present invention discovered that a nozzle in which each of three hollow discharge holes is individually connected to one hollow discharge hole through a slit. The inventors have discovered that by rapidly cooling one side of a porous hollow fiber, the anisotropy in the cross-sectional direction of the fiber is expanded and the texture of the resulting crimped fiber becomes soft, and the present invention has been achieved. That is, the present invention provides a crimped porous hollow fiber made of a thermoplastic polymer and having at least four hollow portions each having a substantially circular cross-sectional shape, the fiber having at least one central portion of the hollow portion. The remaining peripheral hollow part is directly joined to the hollow part, and at least one hollow part of the peripheral hollow part is independently directly joined to the central hollow part, and has cross-sectional anisotropy. In addition, when producing a porous hollow fiber having at least four hollow parts by melt-spinning a thermoplastic polymer, a central discharge hole forming a central hollow part is provided with a peripheral hollow fiber. One side of the discharged yarn discharged from a nozzle in which each of the hollow discharge holes forming the section are individually connected through a slit is rapidly blown with cold air from a direction substantially perpendicular to the traveling direction of the discharged yarn. The resulting undrawn yarn is then stretched and then subjected to a relaxation heat treatment, so that each of the hollow sections has a substantially circular cross-sectional shape, and at least one of the peripheral hollow sections has a substantially circular cross-sectional shape.
This is a method for producing crimped porous hollow fibers, which is characterized by crimping the fibers that are individually and directly joined to the central hollow part. In the present invention, "cross-sectional anisotropy" refers to the existence of physical property differences such as birefringence differences in the fiber cross-sectional direction. The present invention will be explained with reference to the drawings. Fig. 1 shows the cross-sectional shape of the porous hollow fiber of the present invention, Fig. 2 shows the cross-sectional shape of the nozzle for obtaining the porous hollow fiber of the present invention shown in Fig. 1, and Fig. 3 A shows the cross-section of the conventional porous hollow fiber. Figure 3B shows the cross-sectional shape of the nozzle for obtaining the porous hollow fiber of Figure 3A. In FIG. 1 and FIG. 3A, E ₁ to _{E 5} indicate the hollow parts of the husband and husband, and the dotted lines indicate the joining points of the respective hollow parts. As shown in FIG. 1a, the porous hollow fiber of the present invention has a hollow portion having a substantially circular cross-sectional shape.
It is formed of E ₁ to E ₄ , and three peripheral hollow parts E ₂ to _{E 4} are directly connected to the central hollow part E ₁ , and
At least one of the peripheral hollow parts _E2 to _E4 (peripheral hollow part _E4 in FIG. 1a) is independently and directly joined to the central hollow part _E1 , and other peripheral hollow parts It is important that it is not connected to the On the other hand, in the conventional porous hollow fiber shown in FIG. 3A obtained by a nozzle having the cross-sectional shape shown in _FIG .
Although E ₂ to _{E 4} are joined, the hollow parts E ₁ to _{E 4} are joined to two adjacent hollow parts. The porous hollow fiber shown in JP-A-54-112242 as shown in FIG. Moreover, since the cross-sectional shape of each hollow portion is an ellipse, the bulk recovery property is also poor. In _the porous _hollow fiber of the present invention, as shown in _{FIG .} The peripheral hollow part to be joined is shown in Figure 1 c.
As shown in the figure, there may be three or more, which is preferable since the bulkiness can be improved. Such porous hollow fibers of the present invention can be obtained using a nozzle having the cross-sectional shape shown in FIG. Such a nozzle will be explained by taking up the nozzle shown in FIG. 2b. In Fig. 2b, S ₁ to S ₁₁ indicate slits;
The hollow parts E ₁ to _{E 4} shown in Fig. 1b are formed by slits.
It is made up of S ₁ and S ₂ , slits S ₄ and S ₅ , slits S ₇ and S ₈ , and slits S ₁₀ and S ₁₁ . Then, centering on slits S ₄ and S ₅ , slits S ₁ ,
S ₂ , slits S ₇ , S ₈ , and slits S ₁₀ , S ₁₁ are arranged around the slits, and the slits arranged around these slits are connected to the center slit through the slits S ₃ , S ₆ , and S ₉ .
Since they are each independently connected to S ₄ and S ₅ , the peripheral hollow parts E ₂ to _{E 4} are directly joined to the central hollow part E ₁ . The fiber discharged from the nozzle shown in Fig. 2b has a cross-sectional shape as if fibers having a single hollow part were joined together, as shown in Fig. 1b, and one side of the fiber exhibiting such a cross-sectional shape is A high degree of cross-sectional anisotropy can be easily imparted by rapid cooling. On the other hand, as a nozzle for obtaining the porous hollow fibers shown in FIG. 3A, the above-mentioned Japanese Patent Laid-Open No. 112242/1983 discloses a nozzle having the shape shown in FIG. 3B. However, if a substantially rectangular cross-sectional shape is obtained as shown in Figure 3A, even if cooling air is blown onto one side of the fiber, the amount of cooling air that wraps around to the lee side can be reduced, resulting in a fairly high degree of cross-sectional anisotropy. However, it is difficult to obtain such a substantially rectangular cross-sectional shape, and a substantially circular cross-sectional shape is likely to be obtained. For this reason, the cooling air flows around to the leeward side and tends to be uniformly cooled, making it impossible to impart a high degree of cross-sectional anisotropy. Furthermore, unlike the nozzle shown in FIG. 2b, in which four hollow discharge holes are connected in series, when cooling air is blown from one side of the discharged yarn, the bending of the discharged yarn becomes extremely large. Spinning becomes extremely difficult because fusion and the like tend to occur. On the other hand, in a nozzle in which the four hollow discharge holes are arranged in an annular manner and are connected to mutually adjacent hollow discharge holes, the bulk recovery properties of the resulting porous hollow fibers are poor. As the nozzle used in the present invention, in addition to FIG. 2b, the nozzle shown in FIG. can. Next, in the present invention, in order to rapidly cool one side of the fiber having the cross-sectional shape shown in FIG. 1 discharged from the nozzle shown in FIG. It is important to cool down quickly by blowing cooling air from any direction. Here, if the direction in which the cooling air is blown is significantly inclined with respect to the running direction of the discharged yarn, one side of the fiber cannot be rapidly cooled and a high degree of cross-sectional anisotropy cannot be imparted. . The speed of such cooling air is 0.2 m/sec or more, especially 1 m/sec.
m/sec or more is preferable, and the position where the cooling air is blown is more effective as it is closer to the spinneret surface, but in order to maintain good operability, it is necessary to blow the cooling air 1 to 35 cm below the spinneret surface.
is preferred. Although air is the most economical gas for cooling air, any gas may be used as long as it is inert to the polymer melt, and it is preferable that the temperature is as low as possible, but from an economical point of view, ~40°C is preferred. By further drawing the yarn thus obtained and subjecting it to relaxation heat treatment, crimp can be developed. As the stretching conditions at this time, it is preferable to adopt conditions in which the high degree of cross-sectional anisotropy imparted in the spinning process is sufficiently maintained. To describe the stretching conditions specifically for polyester fibers, the stretching temperature is Tg±20°C.
The temperature is preferably within the range of (Tg: glass transition point of polyester), and the stretching ratio is from 65 to the maximum stretching ratio.
95% is preferred. The stretching method may be any method such as liquid bath stretching or pin stretching. Further, the relaxation heat treatment is carried out by making each single fiber constituting the stretched yarn as unrestricted as possible, and then heat-treating it. The heat treatment temperature is preferably 100 to 230°C. Such relaxation heat treatment may be performed in any form such as tow, multifilament, staple, etc., and mechanical crimp may be applied before the relaxation heat treatment. The hollowness ratio of the crimped porous hollow fiber thus obtained is preferably 5 to 60%. The term "hollowness ratio" as used herein is the ratio of the area surrounded by the outer periphery of the cross section to the total area of the hollow portions in the cross section of the fiber. To explain specifically using FIG. 1b, the total area of the hollow portion (SE) is the total area of the hollow portions _E1 to _E4 , and the area surrounded by the outer periphery of the cross section (ST) is the area mentioned above. Hollow area (SE) and area occupied by thermoplastic polymer (SP)
This is the total of That is, the hollowness ratio is expressed by the following formula. Hollowness ratio (%) = SE / SE + SP × 100 When the hollowness ratio exceeds 60%, the hollow part tends to be easily deformed, and when it is less than 5%, it tends to be difficult to impart sufficient anisotropy in the cross-sectional direction. There is. It is preferable that the hollow ratios of the hollow portions forming the porous hollow fibers are approximately the same. The thermoplastic polymer used in the present invention refers to a polymer that can be melt-spun, and examples of such polymers include polyesters such as polyethylene terephthalate and polybutylene terephthalate, and polyolefins such as polyethylene and polypropylene. polyamides such as nylon 6 and nylon 66, and copolymers and polymer mixtures mainly made of these. In particular, it is preferable to use a polyester containing 85 mol % or more of ethylene terephthalate units because it has good thermal properties. In such a polyester, less than 15 mol% of other components such as 5-sodium sulfoisophthalic acid, isophthalic acid, adipic acid, diethylene glycol, polyethylene glycol, polyalkylene glycol, etc. may be copolymerized, especially 5-sodium sulfoisophthalic acid, isophthalic acid, adipic acid, diethylene glycol, polyethylene glycol, polyalkylene glycol, etc. - Those in which a sodium sulfoisophthalic acid component is copolymerized are preferred. In addition, the intrinsic viscosity of such polyester (25
The viscosity (determined from the viscosity measured in 0-chlorophenol at °C) is preferably 0.35 to 0.90. Further, the polymer may contain additives such as a matting agent, an adhesive, an antistatic agent, and a flame retardant. (Function) The conventionally known method of cooling one side of the fiber discharged from the nozzle shown in FIG. 3B cannot impart sufficient cross-sectional anisotropy.
Sufficient crimp cannot be obtained unless physical crimp processing such as a stuffing box or a fluid treatment nozzle is also used. Further, the porous hollow fiber obtained using the nozzle shown in FIG. 3B has an oval cross-sectional shape as shown in FIG. 3A, and the hollow portions are joined in a close-packed state. On the other hand, in the present invention, the cross-sectional shape of the discharged fibers is made into a shape that makes it difficult to be uniformly cooled by the cooling air, so that the cooling air is difficult to wrap around to the leeward side, so that the windward side and the leeward side of the fiber cross section are different. The temperature difference can be significantly increased compared to conventional ones,
It can have a higher degree of cross-sectional anisotropy than conventional ones. Then, as a result of subjecting such fibers to relaxation heat treatment to develop crimps, they can exhibit fine crimps, and since they are porous hollow fibers, they can also exhibit good heat retention and a flexible texture. Moreover, since the range of optimal conditions for obtaining crimped fibers with good uniformity can be set wider than in conventional methods, productivity can be improved and production costs can be reduced. Further, the porous hollow fiber of the present invention is formed of a hollow portion having a substantially circular cross-sectional shape, and the bonding state of the hollow portion is not in a close-packed state, so that the rigidity and hollowness ratio of the fiber itself can be improved. , and the voids between fibers can also be increased. Therefore, the crimped porous hollow fiber of the present invention can prevent the occurrence of "hollow collapse" or "settling" due to bending, etc., and can exhibit excellent bulk recovery properties. Therefore, it can exhibit excellent bulkiness. (Effects of the Invention) When the crimped fiber of the present invention is used for carpets, high piles, moquettes, woven and knitted fabrics for clothing, and especially for stuffing, products exhibiting excellent feather-like characteristics can be obtained. (Examples) Furthermore, the present invention will be further explained by examples. Examples 1 to 3, Comparative Example 1 Polyethylene terephthalate with an intrinsic viscosity of 0.65 measured in 0-chlorophenol at 25°C was
It was melted and discharged at 280° C. from a nozzle having the cross-sectional shape shown in the table, and wound at 750 m/min to obtain an undrawn yarn with a single fiber fineness of 25 denier. To cool the discharged yarn, blow 25°C cooling air at 1.0 cm at a position 0.5 to 15 cm below the mouth surface.
This was carried out by spraying at a flow rate of m/sec from a direction perpendicular to the direction in which the yarn travels. The undrawn yarn thus obtained was bundled into a 700,000 denier tow, which was stretched 3.5 times in a 65°C water bath, dried in tow form, and subjected to relaxation heat treatment in an atmosphere of 130°C. , and cut to 64 mm after crimp development. The staple fibers thus obtained were passed through a card to make a webbing, which was then used as a futon, and its performance was measured. The results are also shown in Table 1.

[Table] As shown in Table 1, compared to Comparative Example 1, the futon cotton using the fiber obtained by the method of the present invention has a specific volume of 110 cm ³ /g or more, a compression rate of 60% or more, and a recovery rate of 90. %
It exhibits excellent bulkiness, resistance to settling, and a soft texture. In Examples 1 to 3, the spinning condition was good, but in the comparative example, spun single fiber breakage occurred. The number of crimp shown in Table 1 is the value measured according to JIS-L1074, and the specific volume, compression ratio, and recovery rate are
This is a value measured according to JIS-L1097. Example 4, Comparative Example 2 The intrinsic viscosity measured in 25°C m-cresol was
Nylon 6 of 1.1 was melted and discharged at 260℃ through the nozzle shown in Figure 2c, taken off at 1500m/min,
An undrawn yarn with a single fiber fineness of 30 denier was obtained. The cross section of this undrawn yarn was a porous hollow cross section as shown in FIG. 1c. The discharged yarn was cooled by blowing cooling air at 25° C. at a flow rate of 0.8 m/sec from a direction perpendicular to the traveling direction of the yarn at a position 1.5 to 10 cm below the face of the spinneret. There was no problem with the spinning condition. This undrawn yarn consisted of 70 single fibers, and was pin-stretched to 3.5 times at a drawing temperature of 50°C, then subjected to relaxation heat treatment in an atmosphere of 130°C, and continuously wound. The obtained drawn heat-treated yarn is JIS-
When crimp performance was measured according to L1074, the number of crimp
It had a good crimp of 13.0 pieces/25mm and a crimp modulus of 91%. Furthermore, when one side was similarly rapidly cooled using the nozzle shown in FIG.
%, which was very poor. Furthermore, single fiber breakage occurred during spinning.

[Brief explanation of drawings]

Fig. 1 shows the cross-sectional shape of the porous hollow fiber of the present invention, Fig. 2 shows the cross-sectional shape of the nozzle for obtaining the porous hollow fiber of the present invention shown in Fig. 1, and Fig. 3 A shows the cross-section of the conventional porous hollow fiber. Figure 3B shows the cross-sectional shape of the nozzle for obtaining the porous hollow fiber of Figure 3A.

Claims (1)

[Scope of Claims] 1. A crimped porous hollow fiber made of a thermoplastic polymer and having at least four hollow portions each having a substantially circular cross-sectional shape, wherein at least one of the hollow portions has a substantially circular cross-sectional shape. The remaining peripheral hollow parts are directly joined to the central hollow part, and at least one hollow part of the peripheral hollow parts is independently joined directly to the central hollow part,
A crimped porous hollow fiber characterized by having cross-sectional anisotropy. 2. The crimped porous hollow fiber according to claim 1, wherein each of the peripheral hollow parts is independently joined to the central hollow part. 3. The crimped porous hollow fiber according to claim 1, wherein the thermoplastic polymer is polyethylene terephthalate. 4. When manufacturing a porous hollow fiber having at least four hollow parts by melt spinning a thermoplastic polymer, each of the hollow discharge holes forming the peripheral hollow part is connected to the hollow discharge hole forming the central hollow part. One side of the discharged yarn discharged from a nozzle connected through a slit is rapidly cooled by blowing cold air from a direction substantially perpendicular to the running direction of the discharged yarn, and then the undrawn yarn obtained By stretching and then subjecting to relaxation heat treatment, each of the hollow sections has a substantially circular cross-sectional shape, and at least one of the peripheral hollow sections is independently and directly joined to the central hollow section. 1. A method for producing crimped porous hollow fibers, characterized by causing the fibers in the fibers to develop crimps. 5. The method for producing a crimped porous hollow fiber according to claim 4, wherein each of the peripheral hollow portions is independently joined to the central hollow portion. 6. The method for producing crimped porous hollow fibers according to claim 4, wherein the thermoplastic polymer is polyethylene terephthalate.