JPH0151563B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a potentially bulky multifilament and a method for producing the same, and more particularly to a potentially bulky multifilament made of filaments having differential shrinkage in the cross-sectional direction and longitudinal direction, and a method for producing the same. (Prior Art) Potentially bulky multifilaments that can exhibit bulkiness by heat treatment can be obtained by mixing filaments with different shrinkages (for example, as disclosed in US Pat. No. 3,200,576). (see book). Such a multifilament is given bulk by the high shrinkage filaments shrinking during heat treatment and the low shrinkage filaments protruding. At this time, if the high shrinkage filament is made of a thick denier and the low shrinkage filament is made of a fine denier, the bulky multifilament after heat treatment will have a firm and soft feel. By the way, in order to obtain a multifilament made of filaments having such a shrinkage difference, a method of mixing a plurality of yarns that have been given a shrinkage difference in advance is often adopted. The following method is proposed in US Pat. No. 4,153,660. That is, in this method, a spun yarn obtained by rapidly cooling a polymer stream discharged from the same spinneret is divided into two yarn bundles, and one of the yarn bundles has a spun finish in which water is the main component. One yarn bundle is coated with an agent that has a boiling point higher than that of water, and then both yarn bundles are separately heat-treated under the same conditions and drawn, and then mixed. It is. This method uses the difference in boiling point of the spinning finishing agents to impart a shrinkage difference between the yarn bundles, but it is necessary to perform extremely complicated operations such as applying two types of spinning finishing agents in this way. . Furthermore, if it is attempted to create a denier difference between the filaments constituting the spun yarns discharged from the same spinneret, troubles such as filaments sticking together due to yarn shaking or yarn breakage are likely to occur. It is necessary to strictly control spinning conditions such as draft rate, cooling air volume, etc. On the other hand, methods for manufacturing potentially bulky multifilaments without such complicated operations are disclosed in JP-A-54-42415 and JP-A-55-51809 (US Pat. No. 4,332,757 and US Pat.
4349604). In this method, polyester flows having two flow differences are discharged through a pair of discharge holes arranged at a certain angle and having different discharge cross-sectional areas, which are arranged in a single spinneret, and a flow of polyester is discharged directly below the spinneret surface. , the high-speed polymer flow discharged from the discharge hole having a small discharge cross-sectional area is joined to the low-speed polymer flow discharged from the discharge hole having a large discharge cross-sectional area of the pair of discharge holes while colliding and vibrating; This is rapidly cooled and wound up, and the resulting multifilament (hereinafter sometimes referred to as pulsing yarn) consists of filaments that have a shrinkage difference in the cross-sectional direction and the longitudinal direction. However, such potentially bulky multifilaments are generally heat-treated after being made into woven or knitted fabrics, but the pulsing yarn has the disadvantage that it lacks bulk in woven or knitted fabrics, especially woven fabrics. have. In other words, the binding force due to the weave structure of the fabric is strong, and the shrinkage force of the pulsing yarn is low.
This is due to the limited shrinkage of the pulsing yarn, resulting in a lack of bulk. In addition, such pulsing yarns have the disadvantage that the shrinkage difference disappears if they are further drawn after spinning, so even those with extremely high shrinkage ratios must be used without being drawn. For this reason, in woven or knitted fabrics using pulsing yarns, wrinkle-like shrinkage spots may occur, and the dyeing and finishing conditions are severely restricted, making it impossible to put them to practical use. Therefore, the present inventors conducted various studies on latent bulky multifilaments that have an extremely large shrinkage force that does not eliminate the difference in shrinkage even after stretching, and developed Japanese Patent Application No. 59-5699 and Japanese Patent Application No. 59-59. This was proposed in specification No. 36097. Such a potentially bulky multifilament is composed of an eccentric hollow filament having uneven thickness in the longitudinal direction, and the degree of orientation of the hollow portion of the constituent filament is extremely greater than the degree of orientation of the adjacent solid portion. Therefore, the difference in shrinkage between filaments and within a filament can be increased, and a multifilament made of such filaments can exhibit sufficient shrinkage force. The latent bulky multifilament can be used after being stretched, since the shrinkage differences between and within the filaments do not disappear even if the multifilament is stretched. For this reason, woven and knitted fabrics using such potentially bulky multifilaments can reduce wrinkle-like shrinkage spots and dyeing spots much more than those using pulsing yarns, but are still insufficient for practical use. Further improvements are desired. Furthermore, the aforementioned shrinkage spots and dyeing spots occur more frequently in latent bulky multifilaments obtained by drawing heat setting than in latent bulking multifilaments obtained by high-speed spinning without drawing heat setting. There was a tendency to (Objective of the Invention) The first object of the present invention is to provide a potentially bulky multifilament that can exhibit both a further improved appearance and a spun-like texture in woven or knitted fabrics, particularly woven fabrics, and a method for producing the same. It is in. The second object of the present invention is to provide a latent bulky multifilament which can be heat-set by drawing to impart mechanical properties suitable for practical use, and which can also exhibit a further improved appearance and spun-like texture. The manufacturing method is to provide. A fourth object of the present invention is to provide a potentially bulky multifilament that can have both a firm and soft touch like a multifilament mixed with different denier filaments and a further improved appearance, and a method for producing the same. It's about doing. (Structure) The present inventors studied to achieve the above object and found that a potentially bulky multifilament used for woven and knitted fabrics exhibiting differential shrinkage and dyeing spots has a high shrinkage part and a low shrinkage part in the longitudinal direction of the multifilament. I learned that contracted parts are ubiquitous. As a result of further studies based on this knowledge, the present inventors have found that by performing a mixed fiber entangling treatment during spinning of the latent bulky multifilant and then taking it out,
The present invention was achieved by discovering that a potentially bulky multifilament in which high-shrinkage portions and low-shrinkage portions are dispersed without being ubiquitous can be obtained. That is, the present invention provides a multifilament composed of filaments made of a melt-spun polymer, in which the constituent filaments are flat and have a pair of recesses facing each other across the long axis on the outer periphery in the long axis direction. and a cross-sectional shape that is asymmetrical with respect to the short axis between the pair of recesses;
An eccentric hollow filament having uneven thickness in the longitudinal direction of the filament, the hollow portion being located on the side where the straight line parallel to the short axis is maximum in the cross section of the filament, and divided by the short axis. A potentially bulky multifilament, characterized in that the degree of orientation of the hollow portion is greater than the degree of orientation of the solid portion adjacent thereto, and the constituent filaments are intertwined. A pair of discharge holes with different discharge cross-sectional areas are connected to each other by a slit, and the discharge hole with a large discharge cross-section is made into a hollow discharge hole with a hollow portion formed by a plurality of slits, and the other discharge hole with a small discharge cross-section is The molten polymer is discharged through the discharge hole of a spinneret having a single discharge hole, and at this time, the polymer flow discharged by the discharge hole having a larger discharge cross-sectional area among the pair of discharge holes. By making the discharge speed of the polymer flow slower than that of the polymer flow discharged from the other discharge hole having a smaller discharge cross-sectional area, the high-speed polymer flow collides with the low-speed polymer flow and joins with the high-speed polymer flow while bouncing, This is a method for producing a latent bulky multifilament, which is characterized in that it is then cooled and solidified, subjected to a fiber mixing and entangling treatment, and then taken off. The present invention will be explained with reference to the drawings. FIG. 1 is a sectional view of a filament constituting the multifilament of the present invention, a side view in the longitudinal direction, and a front view rotated by 90 degrees from the side view, and a and b in FIG. and a graph showing the shrinkage rate in the longitudinal direction of a potentially bulky multifilament exhibiting shrinkage spots and staining spots, 3rd
Figures a and b are graphs showing Worcester spots of the multifilament of the present invention and a conventional pulsing yarn obtained in Example 1 and Comparative Example 3, respectively, which will be described later, and Figure 4 is a cross section of the multifilament of the present invention. Figure 5 is the stress (St)-elongation (E1) curve of the multifilament of the present invention, Figure 6 is a sectional view of the discharge hole of the spinneret for obtaining the multifilament of the present invention, and Figure 7 is the A perspective view (electron micrograph) of the filament immediately after the polymer is discharged in free fall from the discharge hole in FIG. 6a is shown. In Figure 1, n is the major axis, c is the minor axis, x, x
are a pair of recesses facing each other with the long axis n in between,
e is the hollow part, m is the length of the straight line that shows the maximum value among the straight lines parallel to the short axis c in the filament cross section, g is the hollow part divided by the short axis c in the cross section including the hollow part e, and h is the Similarly, it is a solid part divided along the short axis c, and the cross-sectional area of the part g is always larger than that of the part h. In the multi-filament of the present invention, the cross-sectional shape of the filament constituting the filament is flat as shown in FIGS. The hollow portion e is asymmetrical with respect to the short axis c formed as a result, and a hollow portion e exists in the portion g, that is, on the side having the maximum linear length m. The degree of orientation of the g section of the filament cross section having the above-mentioned cross-sectional shape is higher than the orientation degree of the h section, and the degree of orientation of the filament section c and d in the longitudinal direction of the filament is higher than that of the h section.
It has uneven thickness as shown in . Figures 1c and d are side views of filaments constituting the multifilament of the present invention and the side views thereof.
A front view rotated by 90° is shown. As shown in Fig. 1c and d, the thickness unevenness in the longitudinal direction of the filament constituting the multifilament of the present invention has a cross-sectional area of g at a portion h with respect to the longitudinal direction.
They are connected while changing the width to a greater extent than the cross-sectional area of the parts. As described above, in the cross section of the filament constituting the multifilament obtained by the present invention, as shown in FIG. As will be described later, the degree of orientation is much higher than that in the case where the g part is solid due to the large shearing force that is applied during spinning, and this together with the uneven thickness in the longitudinal direction results in an even larger degree of orientation than in conventional pulsing yarns. It can have contractile force. The multifilament of the present invention must be composed of the filaments described above, and the constituent filaments must be mixed and entangled. Therefore, in the multifilament of the present invention,
As shown in FIG. 2a, the phases of the high-shrinkage portion and the low-shrinkage portion of the constituent filaments are not aligned, so that the high-shrinkage portion and the low-shrinkage portion are dispersed in the longitudinal direction. Figures 2a and 2b show the shrinkage rates in the longitudinal direction of the multifilament of the present invention having a mixed fiber entangled portion and a latent bulky multifilament without a mixed fiber entangled portion, respectively. In FIG. 2, the boiling water shrinkage rate of the multifilament was measured at 10 cm intervals and the results were plotted. As is clear from FIG. 2, the multifilament of the present invention having the mixed fiber entanglement shown in FIG. In addition, as mentioned above, there is a large shrinkage difference within the filament and between the filaments, so there is no grain-like shrinkage spots or staining spots, and the product has a heather-like appearance and spun-like texture. A uniform woven or knitted fabric exhibiting this can be obtained. On the other hand, in the case shown in FIG. 2b, the phases of the high-shrinkage portion and the low-shrinkage portion of the constituent filaments are aligned with each other, so that the high-shrinkage portion and the low-shrinkage portion are ubiquitous in the longitudinal direction. Although woven or knitted fabrics using such latent bulky multifilaments exhibit a spun-like texture, they develop grain-like shrinkage spots and band-like dyed spots, resulting in poor commercial value. As described above, in the multifilament of the present invention, in which a woven or knitted fabric exhibiting a good appearance and feel can be obtained, the difference from the maximum shrinkage rate in the longitudinal direction is preferably 35% or less, particularly 5 to 30%. When the shrinkage rate exceeds 35%, high shrinkage parts and low shrinkage parts tend to become ubiquitous.
Improvement of wrinkle-like shrinkage spots and staining spots may be insufficient. Furthermore, the number of entanglements in the multifilament of the present invention is preferably 10 or more, particularly 15 to 80/m. If this number of entanglements is less than 10 pieces/m,
There is a tendency for wrinkle-like shrinkage spots and dyeing spots in the resulting woven or knitted fabric, as well as for insufficient improvement in the texture. In the present invention, preferred embodiments of the filament's cross-sectional shape are those that exhibit a substantially eyebrow shape as shown in FIG. 1a, or those that exhibit a substantially isosceles triangle shape as shown in FIG. 1b. In particular, a filament having a substantially isosceles triangular cross-sectional shape is preferred because it can exhibit a unique luster. The hollowness ratio of the g portion in such a flat hollow filament is 2 to 30%, particularly preferably 10 to 30%.
15%, cross-sectional area including hollow part e of part g
The ratio of Sg to the cross-sectional area Sh of the h portion (Sg/Sh) is 1.2 ~
3, particularly preferably 1.5 to 2. However, the hollowness ratio and cross-sectional area Sg and Sh are determined from a micrograph of a cross-section of the filament. Furthermore, as shown in Fig. 1 c and d, a filament in which the h section is joined to the g section in the longitudinal direction of the filament without being wrapped is preferable because the degree of deformation in the longitudinal direction, that is, the thickness unevenness is large. be. The multifilament of the present invention, which is composed of filaments having large thickness unevenness in the longitudinal direction, naturally also has large thickness unevenness in the cross-sectional direction. This is clear from the Worcester spot graph of the multifilament of the present invention obtained in Example 1, which will be described later, shown in FIG. Even when compared with the graph of Worcester's unevenness of the pulsing yarn, the thickness unevenness of the multifilament of the present invention in the cross-sectional direction is large. Incidentally, such Worcester spots were determined using the Worcester Evenness Tester Model C manufactured by Zellweger Worcester. In addition, large thickness unevenness [the length (L) from peak to peak is 0.5 to 3 m] as shown in Fig. 1 exists randomly in the longitudinal direction of the filament constituting the multifilament of the present invention. In an arbitrary cross section of a multifilament made of filaments,
As shown in FIG. 4, the same effect is obtained as if filaments having different deniers were mixed together. In other words, in Fig. 4, A indicates the filament cross section which is the maximum cross-sectional area in one multifilament cross section, and n ₁ and m ₁ are the filament cross sections (A).
The long axis and maximum linear length of are shown, respectively. In addition, B indicates the filament cross section with the minimum cross-sectional area in one multifilament cross section shown in Fig. 5, and n ₂ and m ₂
indicate the long axis and maximum linear length of the filament cross section (B), respectively. Generally, when filaments with different cross-sectional areas as shown in Figure 5, i.e., filaments with different deniers, are mixed, the filaments with a large cross-sectional area (thick denier) have a small cross-sectional area (fine denier). Because the shrinkage rate is higher than that of filaments, thick denier filaments shrink and become tension carriers through heat treatment, and fine denier filaments protrude to the outside of multifilaments, creating a firm and soft texture. In the multifilament of the present invention, the filament (A) with the maximum cross-sectional area and the filament (B) with the minimum cross-sectional area that satisfy the following formula [] have a firm and soft texture. n ₁ ×m ₁ /n ₂ ×m ₂ ≧1.5 ... [] Furthermore, the multifilament obtained by the present invention has large spots, i.e., large spots in the cross-sectional direction and longitudinal direction, as described above. Since it has a large shrinkage difference, it has a structure as if it were a mixture of filaments with shrinkage differences between and within the filaments.For this reason, the stress-elongation curve of the multifilament of the present invention is as shown in Figure 5. Here, Figure 5a is the stress (St)-elongation (E1) curve of the multifilament of the present invention obtained by mixing and entangling the fibers immediately before spinning and taking off. Figure b shows the stress (St) - elongation (E1) curve of the multifilament obtained by further drawing after spinning. In Figure 5, L ₁ is the final elongation at break, and L ₂ is the maximum stress. In this way, the elongation of L ₁ and L ₂ is a characteristic of the mixed fiber yarn made by mixing filaments with the above-mentioned shrinkage difference. In a multifilament made of filaments with very small shrinkage or with no difference in shrinkage, only _L2 is normally observed.In this respect, the multifilament of the present invention is as if it were a mixed fiber yarn made of filaments with a difference in shrinkage. The same effect can be exhibited.The larger the value of (L ₁ - L ₂ ) _is , the larger _the shrinkage difference is.
A multifilament whose value satisfies the following formula [ ] is preferable because a woven or knitted fabric exhibiting sufficient bulkiness can be obtained. L-L ₂ ≧20%...[] The multifilament of the present invention can be used not only in an undrawn state, but also when stretched and heat-set to impart mechanical properties that can withstand practical use. It is possible to obtain one that satisfies the above formula [ ]. The multifilament of the present invention described above can be obtained for the first time by the manufacturing method of the present invention, which employs a spinneret having the discharge holes shown in FIG. can. FIG. 6 is a sectional view of the discharge holes of the spinneret employed in the production method of the present invention, in which 1a to 1c, 2, and 3 are discharge holes for discharging polymer streams, and 4 is 1
A hollow part formed by a plurality of slits indicated by a to 1c, 2 is a single discharge hole, 3 is a hollow discharge hole consisting of slits 1a to 1c and a hollow part 4, and the single discharge hole 2 is connected. slit, lA ₂ is the inner diameter of the single discharge hole, l and W are the width and length of the slit 3,
lA ₁ and lB ₁ respectively indicate the outer diameter and inner diameter of the hollow discharge hole in FIG. 6a. The characteristics of such discharge holes are that they have different discharge cross-sectional areas.
As the pair of discharge holes, a hollow discharge hole composed of a plurality of slits 1a to 1c is adopted for the discharge hole with a large discharge cross-sectional area, and a single discharge hole 2 is adopted as the other discharge hole with a small discharge cross-section. Specifically, the hollow discharge hole and the single discharge hole 2 are connected by the slit 3. In the multifilament manufacturing method of the present invention, the polymer flow discharged from the hollow discharge hole of the discharge hole shown in FIG. It is necessary to combine the polymer streams discharged from the holes 2 while colliding and bouncing, and then to perform a fiber-mixing and entangling treatment after being cooled and solidified, and then to take them off. By employing the multifilament manufacturing method of the present invention, it is possible to increase the shrinkage difference within and between the filaments constituting the obtained multifilament, thereby improving the shrinkage force of the multifilament. At the same time, high shrinkage portions and low shrinkage portions in the longitudinal direction of the multifilament can be dispersed. Here, in the discharge holes shown in FIG. 6, if the total discharge cross-sectional area (S ₁ ) of the slits 1a to 1c of the hollow discharge hole and the discharge cross-sectional area (S ₂ ) of the single discharge hole 2 are specified, the spinning Collision of polymer flow directly below the mouthpiece
Since the bounce becomes too intense, stable spinning becomes difficult. Furthermore, if a discharge hole in which the hollow discharge hole and the single discharge hole 2 are not connected by the slit 3 is used, the shrinkage difference within and between the filaments of the resulting multifilament will be insufficient. Furthermore, in the multifilament obtained by pulling the fibers without intertwining, high shrinkage areas and low shrinkage areas are omnipresent in the longitudinal direction, so the final woven or knitted fabric has a spun-like texture. However, wrinkle-like shrinkage spots and staining spots are likely to occur. The filaments constituting the multifilament obtained by the production method of the present invention are shown in FIGS.
A flat hollow filament having a cross-sectional shape shown in FIG. The degree of orientation of the hollow part existing part divided into parts is greater than the degree of orientation of the adjacent solid part, and it also has uneven thickness in the longitudinal direction as shown in Fig. 1c and d. -ing In addition, in FIG. 1, a pair of recesses indicated by x and x' are a junction where the polymer flow discharged from the single discharge hole 2 joins the polymer flow discharged from the hollow discharge hole in FIG. 6. Department. Then, in the cross section of the filament, the degree of orientation of the section g, which has a larger cross-sectional area than the section h, is defined as h
One of the features of the manufacturing method of the present invention is that the degree of orientation of the filament can be made larger than that of the filament. As mentioned above, as a result of the large shrinkage force, a large contractile force can be exhibited. The reason why such a filament can be obtained by the production method of the present invention is considered to be as follows. That is, in general, if the flow velocity of the polymer flow passing through each slit constituting a hollow discharge hole and a single discharge hole is equal to each other, the total pressure loss of the plurality of slits in the hollow discharge hole is equal to that of the single discharge hole. It is larger than the hole. However, in the discharge hole shown in FIG. 6, which has a hollow discharge hole and a single discharge hole 2 in the same discharge hole through a slit 3, the pressure loss of both holes is made equal. A flow velocity difference is created between the polymer streams passing through the polymer. Therefore, by adjusting the slit width of the hollow discharge hole, the inner diameter lA ₂ of the single discharge hole 2, etc., the polymer discharged from the single discharge hole 2 can be made smaller than the slits 1a to 1c of the hollow discharge hole. It is possible to provide a flow velocity difference so that the flow velocity of the flow becomes faster, and to easily increase the flow velocity difference. In this way, since the flow rate of the polymer flow passing through the slits 1a to 1c of the hollow discharge hole is slower than the polymer flow passing through the single discharge hole 2, the spinning draft is discharged from the slits 1a to 1c of the hollow discharge hole. is mainly concentrated in the polymer stream. In particular, in high-speed spinning, as a result of high draft concentrating on the polymer flow discharged from the slits 1a to 1c of the hollow discharge hole, the hollow portion formed by the polymer flow is formed when the hollow discharge hole is a single discharge hole. The polymer stream experiences a much higher degree of orientation than if it were solid. In addition, since the discharge cross-sectional area (S ₂ ) of the single discharge hole 2 is smaller than the total discharge cross-sectional area (S ₁ ) of the slits 1a to 1c of the hollow discharge hole, the g side including the hollow part in the obtained filament cross section is h than the cross-sectional area
The cross-sectional area of the side becomes smaller. Furthermore, since the flow speeds of the polymer discharged from the hollow discharge hole and the single discharge hole 2 are different, and the two polymer streams are connected by the polymer flow discharged from the slit 3, the flow rate of the polymer discharged from the hollow discharge hole is different. As a result of the polymer flow discharged from the single discharge hole 2 colliding and bouncing with the discharged polymer flow, as shown in Fig. 1c,
As shown in d, a filament having uneven thickness in the longitudinal direction is obtained. Moreover, in the manufacturing method of the present invention, since the multifilament made of the filaments is taken up after being subjected to a fiber-mixing and entangling treatment, the obtained multifilament has a phase difference between the high shrinkage part and the low shrinkage part of the constituent filaments. The high shrinkage portions and low shrinkage portions are dispersed in the longitudinal direction, as shown in Figure 2a, without being aligned with each other. In the filament constituting the multifilament obtained by the manufacturing method of the present invention, in its cross section, the degree of orientation of the part g, which has a larger cross-sectional area including the hollow part than the part h, as shown in FIG. 1, is high,
In addition, since the degree of orientation is much higher than when the g part is solid, there is a large difference in shrinkage within and between the filaments that make up the conventional pulsing yarn due to uneven thickness in the longitudinal direction. , high shrinkage portions and low shrinkage portions are distributed in the longitudinal direction. The arrangement shape of the slits of the hollow discharge holes and the cross-sectional shape of the single discharge hole employed in the manufacturing method of the present invention do not need to be particularly limited, and the optimum shape may be adopted depending on the purpose. For example, the slits of the hollow discharge holes may be arranged in a non-circular shape as described in British Patent No. 853062, and the triangular arrangement shown in FIG. 6b is particularly preferred. According to the discharge hole shown in FIG. 6b using such a triangular hollow discharge hole, a filament having a substantially isosceles triangular cross-sectional shape shown in FIG. 1b can be obtained. Further, if the slit array shape of the hollow discharge holes and the cross-sectional shape of the single discharge hole are circular as shown in FIG. 6a, the cross-sectional shape will be approximately cocoon-shaped as shown in FIG. 1a.
The discharge hole shown in FIG. 6a is preferred because it is easy to work with. Furthermore, in FIG. 6, by connecting the single discharge hole 2 and the hollow discharge hole with the single slit 3, surprisingly, the polymer flow discharged from the single discharge hole 2 is connected to the hollow discharge hole. Since the polymer flow discharged from the filament collides and bounces on one side of the filament, the filament shown in FIG.
Large unevenness in thickness can be provided in the longitudinal direction of the filament. In this way, multifilaments made of filaments that have large orientation differences in the cross-sectional direction of the filaments and large thickness variations in the longitudinal direction of the filaments can be put to practical use by further drawing and heat setting after spinning. Even if mechanical properties are imparted, sufficient contractile force can be exhibited, which is preferable.
The shape of the slit 3 is not limited to the straight shape shown in FIG. 6, but may also be hook-shaped or curved. The important point is that the hollow discharge hole and the single discharge hole 2 are connected by a slit. On the other hand, according to the experiments of the present inventors, pulsing yarn was produced using the spinneret described in JP-A-55-51809 (U.S. Pat. No. 4,332,757 and U.S. Pat. No. 4,349,604). In order to obtain a polymer flow discharged from a discharge hole having a large discharge area, a polymer flow discharged from a discharge hole having a small discharge cross-sectional area is wrapped around and joined to a multifilament. Therefore, it was difficult to provide large irregularities in the longitudinal direction of the filament. Furthermore, by setting the length of the slit 3 so that the recesses x and x' shown in FIG. The vibration period due to collision and bounce of both polymer flows can be made larger, and extremely large unevenness in thickness can be imparted to the obtained filament in the longitudinal direction. Then, a flat hollow filament having the cross-sectional shape shown in FIG. 1 can be obtained using the discharge hole shown in FIG. %,
Particularly preferably 10 to 15%, the hollow part e of part g
It is preferable that the ratio (Sg/Sh) of the cross-sectional area Sg including the cross-sectional area Sg to the cross-sectional area Sh of the h portion is 1.2 to 3, particularly 1.5 to 2. In the discharge holes adopted in the present invention, the single discharge hole 2 shown in FIG. 6 may be connected to one or more hollow discharge holes, and the shape of the single discharge hole 2 may also be triangular, square, Y-shaped, etc. It may be non-circular. The specific dimensions of the discharge hole of the present invention described so far are shown below for the discharge hole of FIG. 6a. 1.5≦S ₁ ／S ₂ ≦15 0.04≦(lA ₁ −lB ₁ ) /2≦0.30 0.10≦lA ₂ ＜lB ₁ ＜lA ₁ ≦1.5 0.05≦l≦1.30 0.03≦W＜lA ₂ ≦1.0 [However , The units of lA ₁ , lB ₁ , lA ₂ , l, and W are (mm). ] By employing a spinneret having such discharge holes, it is possible to easily obtain a multifilament as if filaments of different deniers were mixed together. In addition, in the multifilament manufacturing method of the present invention, the flow velocity (v ₁ ) of the polymer flow discharged from the hollow discharge hole and the flow velocity (v ₂ ) of the polymer flow discharged from the single discharge hole 2 are determined. The discharge speed ratio (v ₁ /v ₂ ) is 1/
It is preferable to set it to 1.5 to 1/7, especially 1/2.3 to 1/3.4, and at this time, the polymer discharge rate ratio [discharge rate of hollow discharge hole/discharge rate of single discharge hole 2] is 3/
It is preferable to set it to 1 to 1/5, particularly 1.5/1 to 1/3.3. Now, FIG. 7 shows the shape of a spun filament obtained just below the surface of a spinneret having a discharge hole shown in FIG. 6a and within the range of the dimensions described above. Figure 7 is obtained in free fall, and shows that the cross-sectional area on the side discharged from the hollow discharge hole hardly changes, but the cross-sectional area on the side discharged from the single discharge hole changes. It shows. Furthermore, FIG. 7 also shows that the polymer flow discharged from the single discharge hole vibrates in one direction without wrapping around the polymer flow discharged from the hollow discharge hole. However, since the spun filament shown in FIG. 7 was obtained in a free fall state that is not affected by the spinning draft, the cross-sectional shape is different from that of the filament constituting the multifilament obtained by the present invention. , Under the spinning draft action, the solid part bounces and connects to the hollow part, so the length of the solid part becomes longer than the hollow part.
A filament having the filament cross-sectional shape shown in FIG. 1a is obtained. After the polymer stream discharged and joined in this manner is cooled and solidified, it is subjected to a fiber-mixing and entangling treatment, and then taken off. As the method for the fiber mixing and entangling treatment at this time, any commonly used method such as electrospreading, Taslan nozzle, interlace nozzle, etc. can be arbitrarily adopted. The method is preferred. As such an interlace nozzle,
No. 12230 or Japanese Patent Application Laid-Open No. 1175/1975 (U.S. Patent Nos. 3069836, 3083523, and 3110151)
It is possible to adopt those known for example. The number of entanglements imparted during the above-mentioned fiber-mixing entangling treatment is 10 or more, particularly 15 to 80. It is preferable in terms of uniform dispersion and the feel of the final product, woven or knitted fabric. In addition, the higher the collection speed, the
As the spinning draft increases, the degree of orientation of the hollow part g of the filament increases and the shrinkage difference with the solid part h can be expanded, so if the take-up speed is 2500 m/min or more, high spinning of 500 or more is possible. It is preferable to be able to provide a draft. Furthermore, by stretching the multifilament taken after the fiber blending process and heat setting it at a temperature of 100°C or higher, the mechanical properties of the resulting multifilament can be improved to a level that can be put to practical use. A woven or knitted fabric that still has a large shrinkage force even when the temperature is increased, and that the high-shrinkage portion and the low-shrinkage portion are evenly distributed in the longitudinal direction, so that it exhibits a good appearance and texture after heat treatment. is obtained. Here, if the multifilaments obtained after drawing are subjected to drawing without performing the fiber-interlacing treatment, the low shrinkage parts (fine denier parts) of the constituent filaments are easier to draw than the high shrinkage parts (thick denier parts). The difference between the high shrinkage portion and the low shrinkage portion is likely to be magnified. In this way, even for multifilaments in which the difference between the high-shrinkage portion and the low-shrinkage portion has increased, the shrinkage difference can be reduced by applying the fiber-mixing and entangling treatment, but performing the treatment after stretching is insufficient. There is a tendency for this to happen. On the other hand, if the spinning take-off speed is 4000 m/min or more, especially
At a speed of 4,500 to 5,500 m/min, the multifilament obtained can be put to practical use as it is, and it goes without saying that it can be given sufficient bulk by heat treatment. The cross-sectional shape of each filament in an arbitrary cross section of the multifilament obtained in this way is the first
As shown in the figure, there is a filament having a shape that does not have the concave portions x and x' in the filament cross section shown in FIG. 1, even if the cross-sectional shape is flat. Even if there are filaments with such a cross-sectional shape, a multifilament in which the number of filaments is small can sufficiently achieve the object of the present invention. In melt spinning to obtain the multifilament of the present invention as described above, even if the polymer stream discharged from the spinneret is cooled with cooling air and taken out as in normal melt spinning, it is not necessary to further heat it after cooling. You may take it back after applying it. In addition, methods for stretching and heat setting after melt spinning include melt spinning, winding once, stretching in a separate process and heat setting, or melt spinning and then stretching without winding. A heat setting may also be applied. The melt-spun polymer targeted in the present invention is polyethylene terephthalate, in which 85 mol% or more of the repeating units are substantially composed of ethylene terephthalate, and the polymer has matting properties and improved dyeability. , additive substances for various purposes such as antistatic properties may be included as a copolymer or a blend. The intrinsic viscosity of polyethylene terephthalate (measured in orthochlorophenol at 35°C) is
0.45-1.20 is preferred, particularly 0.50-1.00. When the intrinsic viscosity is less than 0.45, the strength level of the resulting multifilament is unfavorably low. In addition, when the intrinsic viscosity exceeds 1.20, the melt viscosity during spinning is too high and it is necessary to raise the melting temperature, which is not preferable. Furthermore, it goes without saying that a commonly used melt spinning apparatus can be used as the melt spinning apparatus used in the present invention. (Function) The discharge holes of a conventional spinneret for obtaining pulsing yarn are provided with a pair of discharge holes with different discharge cross-sectional areas facing each other at a certain angle, and a discharge hole with a small discharge cross-sectional area. The length (land length) of the polymer guide hole of the hole is set shorter than the length (land length) of the polymer guide hole of the discharge hole having a large discharge cross-sectional area.
With this setting, the flow rate of the polymer flow discharged from the discharge hole having a small discharge cross-sectional area is faster than the polymer flow discharged from the other discharge hole. In this way, a pair of polymer streams having different flow velocities are joined while colliding and vibrating just below the spinneret surface, making it possible to provide a certain degree of shrinkage difference in the cross-sectional direction and longitudinal direction of the filament. However, as mentioned above, the shrinkage force of the pulsing yarn is insufficient, so in order to increase the shrinkage force in the cross-sectional direction of the filament, the difference in discharge cross-sectional area is increased to obtain a cross section on the high orientation side of the filament. Even if the area is not increased, the difference in flow velocity between the polymer flows discharged from both holes is created by adjusting the land length of the discharge holes, etc.
The greater the difference in discharge cross-sectional area, the more difficult it becomes to apply a flow velocity, so there is a limit to the use of such a pair of discharge holes. Furthermore, even if the vibration caused by the collision of both polymer flows is made more intense and unevenness in the longitudinal direction of the filament is increased, if the installation distance between both holes is increased, the vibration will decrease or even disappear. be. On the other hand, in the multifilament manufacturing method of the present invention, since a spinneret having a discharge hole as shown in FIG. As a result of being able to have the effect of making the action points of the spinning draft ubiquitous on the discharged polymer flow,
There are large thickness irregularities in the longitudinal direction of the filament, and
As shown in the figure, a multifilament made of filaments having a cross-sectional orientation difference in which the g-side orientation is higher than the h-side orientation can be obtained. That is, by adjusting the slit width of the plurality of slits constituting the hollow discharge hole and the hole diameter of a single discharge hole, the flow velocity difference between the polymer flows discharged from the pair of discharge holes can be made sufficiently large. can do. Therefore, the spinning draft can be concentrated on the polymer flow discharged from the hollow discharge hole, and a large shearing force acts on the polymer flow discharged from the hollow discharge hole, so that the degree of orientation in the hollow portion is lower than that in the solid portion. It is possible to achieve an orientation degree higher than that of the hollow portion, and an extremely higher degree of orientation than when the hollow portion is solid. Moreover, since the total discharge cross-sectional area of the plurality of slits constituting the hollow discharge hole is larger than the discharge cross-sectional area of a single discharge hole, in the cross section of the obtained filament, the cross-sectional area of the hollow portion is larger than that of the solid portion. Further, even if the distance between the two holes is increased, since the holes are connected by the slit, both polymer flows can be joined while generating large vibrations due to collision and bouncing. Furthermore, in the production method of the present invention, the bonded polymers are cooled and then subjected to a fiber-mixing and entangling treatment to shift the phase of the high-shrinkage portion and the low-shrinkage portion of the constituent filaments. High shrinkage portions and low shrinkage portions can be distributed in the longitudinal direction of the filament. In the filament constituting the multifilament of the present invention obtained in this manner, in its cross section, the hollow portion has an extremely high degree of orientation, and the cross-sectional area of the hollow portion is larger than that of the solid portion. In addition to having a larger shrinkage rate than that of filaments, the filaments also have large thickness variations in the longitudinal direction, so multifilaments made of such filaments have large shrinkage differences between and within the filaments. , can exhibit large shrinkage force during heat treatment. Moreover, since the constituent filaments are mixed and entangled and have entangled parts, when the high shrinkage part of the filament shrinks during heat treatment, the low shrinkage part is simultaneously placed on the outside of the multifilament without entangling. Compared to the above, it can protrude further and exhibit even more bulkiness. In textiles using such multifilaments,
By heat treatment, uniform and sufficient bulkiness can be exhibited. In addition, multifilament, which is obtained by further drawing and heat setting the undrawn yarn obtained by melt spinning to give it mechanical properties that can be put to practical use,
Since the fabric still has sufficient shrinkage difference and the high shrinkage portion and low shrinkage portion in the longitudinal direction are dispersed, the fabric using such multifilament also exhibits uniform and sufficient bulkiness by heat treatment. be able to. Furthermore, in the present invention, when the discharge hole shown in FIG. 6b in which the slits of the hollow discharge hole are arranged in a triangular shape is used, the cross-sectional shape of the obtained filament can be made into a substantially isosceles triangle as shown in FIG. 1b. is possible,
A multifilament made of such filaments can exhibit a unique luster. In addition, the filaments constituting the multi-filament of the present invention have large irregularities in thickness randomly in the longitudinal direction, and the phases of the fine denier and thick denier parts do not align, so filaments of different deniers are mixed. It can also exhibit a nice, firm feel like a blended yarn. (Effects of the Invention) The multifilament obtained by the present invention can exhibit uniform and large bulkiness simply by heat treatment, so it can be handled as a flat yarn in the weaving and knitting process, so it has good process passability. . Moreover, since it can be obtained from a single polymer without complicated operations, its industrial potential is extremely large. (Example) The present invention will be further explained in Examples below, and the physical properties used in the Examples were measured by the following method. (1) For arbitrary cross sections of n ₁ , m ₁ and n ₂ , m ₂ multifilament,
Take a cross-sectional photograph at a magnification of 560 parts, and determine the long axis n ₁ of the filament cross-section where the cross-sectional area including the hollow part is maximum.
and the maximum linear length m ₁ , and the long axis n ₂ of the filament cross section with the minimum cross-sectional area and the maximum value m ₂
were measured respectively. (2) Elongation at maximum stress (L ₂ ) and final elongation at break (L ₁ ) A sample length of 10 cm was measured in a normal tensile tester at 25°C and 60% humidity in a greenhouse. Tensioning speed 200mm/
A stress-elongation curve was obtained under the conditions of mm, and the elongation at which the stress was maximum (L ₂ ) and the elongation at which the stress became zero were determined as the final elongation at break (L ₁ ). (For measurements, n = 5, and the average value was adopted.) (3) Shrinkage variation in the longitudinal direction of the multifilament Marks were placed on the multifilament at 10 cm intervals under a load of 2 mg/de, and the sample length was 9 m. As a sample for measurement, this was placed in a ``case'' and treated in boiling water for 20 minutes under no load. Thereafter, the "skein" was released, and changes in each partial shrinkage rate were continuously determined in the longitudinal direction using the following formula under a load of 2 mg/de. Shrinkage rate (%) = [(10-l <sub>1</sub> ) / 10] × 100 [l <sub>1</sub> : Length after boiling water repair of each part marked at 10 cm intervals] (4) Number of entanglements The number of entanglements is the length of the sample approximately 70 cm long. Float a sample length of 25cm in water at 50℃ for 30 seconds and read with the naked eye. Repeat this operation 4 times and convert to the number of entanglements per 1 m. (5) Texture (bulky feel and spun-like feel) The obtained latent bulky multifilament was knitted into a cylinder, dyed using a disperse dye in a conventional manner, washed with water, dried, and then set at 180°C for 1 minute to determine the texture. This was used as a sample for evaluation (bulky feeling and span-like feeling). The texture was evaluated by visual observation and tactile sensation. (6) Shrinkage rate of multifilament The average shrinkage rate of multifilament was measured by the following method. (a) Boiling water shrinkage rate Make a ``skein'' of multifilament and shrink this ``skein'' in boiling water for 30 minutes without applying any load.
The shrinkage rate when treated for minutes was determined from the following formula. [(l ₀ - l ₁ )/l ₀ ] x 100 = Shrinkage rate (%) (l ₀ : Length of "umbrella" before treatment) (l ₁ : Length of "umbrella" after treatment) (b ) Dry heat shrinkage rate at 120℃ Make a "skein" of multifilament, apply a load equivalent to 2.5mg to this "skein", and shrink at 120℃.
The shrinkage rate when dried for 5 minutes was determined from the following formula. [(l ₀ - l ₁ )/l ₀ ] x 100 = Shrinkage rate (%) (l ₀ : Length of "umbrella" before treatment) (l ₁ : Length of "umbrella" after treatment) Example 1. Polyethylene terephthalate (containing 0.3% by weight of TiO ₂ as a matting agent) with an intrinsic viscosity [η] of 0.64 was melted and spun at a spinning temperature of 300°C through the discharge hole shown in Figure 6a at 37.5mg/min. It was discharged at the discharge amount. Table 1 shows the dimensions of each part of the discharge hole used here.

[Table] In such a discharge hole, the discharge amount ratio and discharge speed ratio of polyethylene terephthalate (hereinafter referred to as PET) discharged from the hollow discharge hole and the single discharge hole 2 were 1/1.7 and 1/3.3, respectively. . Then, the polymer flow discharged from the single discharge hole 2 collides and bounces onto one side of the polymer flow discharged from the hollow discharge hole directly below the spinneret. The bonded PET stream was then heated to a temperature of 26°C and a humidity of 60°C.
% cooling air was blown at a linear velocity of 3 cm/sec to cool and solidify, an oil was applied with an oiling roller, and the material was rolled up at a take-up speed of 4500 m/mm to obtain a 75 de/36 fil multifilament. During winding, an interlace nozzle was installed and the fibers were mixed and entangled under the conditions of an overfeed rate of 2% and an air pressure of 5 kg/cm ² of the interlace nozzle. The filament constituting this multifilament had a cross-sectional shape as shown in FIG. Furthermore, the filaments also have large thickness irregularities in the longitudinal direction, and the Worcester irregularities of this multifilament are shown in Figure 3a.
As shown in the figure, it was large. Then, for the obtained multifilament, the ratio of the maximum and minimum values of the filament cross-sectional area in an arbitrary cross-section (n ₁ × m ₁ /n ₂ × m ₂ ), the cross-sectional area Sg including the hollow part e of the part g, Cross-sectional area of h part
The ratio to Sh (Sg/Sh), stress-elongation curve, and yarn physical properties were measured and shown in Table 2.

[Table] In addition, the number of entanglements in the obtained multifilament was 15 pieces/m, and the change in shrinkage rate in the longitudinal direction of the multifilament was shown in Figure 2a. The difference in rates was 30%. Since the L ₂ of this multifilament is as low as 75%, it can be put to practical use as it is without further stretching and heat setting. For this purpose, the multifilament was knitted into a tube and dyed by dispersion dyeing under the following conditions. [Dyeing] Dye: Polyester Eastman Blue Dye ratio: 4% of the tube knitting weight Auxiliary agent: Monogen (0.5%/) Bath ratio: 1/100 Temperature x time: 100 x 60 minutes Wash the dyed sample with water After drying, it was heat set at 180°C for 1 minute. Five tube-knit dyed samples prepared in this way were prepared, and the dyed spots and texture were visually judged. (1) Staining spots The dark and light staining areas were extremely uniformly dispersed, giving a heather-like appearance, and no staining spots were observed.
Moreover, no difference between samples (n=%) was observed. (2) Texture (a) Bulkyness The fine denier components were concentrated around the thick denier components, giving it a firm feel and the same bulkiness as when using a normal woolly type material. In addition, no bulky spots were observed. (b) Spun-like feel Since the fine denier components are concentrated around the thick denier components, the tube-knitted surface has an extremely natural and fine uneven feel, giving it a strong spun-like feel. Comparative Example 1 A multifilament was spun in the same manner as in Example 1 and wound at 4500 m/min without being mixed and entangled. After tube knitting and dyeing, the dyeing unevenness and texture were evaluated. The change in shrinkage rate of the multifilament in the longitudinal direction is shown in FIG. 2b, and the difference between the maximum shrinkage rate and the minimum shrinkage rate was 40%. (1) Stained spots The darkly stained and lightly stained areas are relatively dispersed, but
In some places, the dark and light dyed areas were clustered together, and there were areas where the difference in shade was band-like. Also, between samples (m=
%), a difference in contrast was observed. (2) Texture (a) Bulkyness As in the case of Example 1, the bulkiness is sufficiently large, but there are shrinkage spots and bulky spots here and there, and there is also variation between samples (m = 5). It was observed. (b) Spun-like feeling Although there was a spun-like feeling, the tube-knitted surface had little unevenness, so the spun-like feeling was not as great as in Example 1. Example 2 The yarn was spun in the same manner as in Example 1, except that the take-up speed was 3000 m/min and the discharge rate was 35 g/min.
Obtained 36fil multifilament. The number of entanglements in the obtained multifilament was 35 pieces/m. Next, this undrawn yarn was preheated and drawn, heat set using a slit heater, and then drawn and heat set under the following conditions to obtain a drawn multifilament of 75 de/36 fil. [Stretching heat setting conditions] Preheating temperature 80°C Heat setting temperature (slit heater temperature) 240°C Stretching ratio 1.4 Stretching take-off speed 500 m/min Table 3 shows the properties of this drawn multifilament.

[Table] The number of entanglements obtained by stretching was 22/m. The shrinkage rate change in the longitudinal direction of this drawn multifilament was as shown in Figure 2a, and the difference between the maximum shrinkage rate and the minimum shrinkage rate was 20%. This tubular knitting using multifilament was dyed under the same dyeing conditions as in Example 1,
This was used as a sample for staining spots and texture evaluation. As shown below, as in Example 1, a product with few staining spots and an excellent texture was obtained. (1) Staining spots The dark and light staining areas were extremely uniformly dispersed, giving a heather-like appearance, and no staining spots were observed.
Moreover, no difference between samples (n=5) was observed. (2) Texture (a) Bulkyness The fine denier components are concentrated around the thick denier components, giving it a firm waist and great bulk.
No bulky plaques were observed. (b) Spun-like feel Since the fine denier components are concentrated around the thick denier components, the tube-knitted surface has an extremely natural and uneven feel, giving a strong spun-like feel. Comparative Example 2 In the same manner as in Example 2, at a spinning speed of 3000 m/min,
The fibers were rolled up without being subjected to the interlacing treatment using the interlace nozzle. The stretching operation was also carried out in the same manner as in Example 2. The change in shrinkage rate in the longitudinal direction of this stretched multifilament was as shown in Figure 2b, where the difference between the maximum shrinkage rate and the minimum shrinkage rate was 36%. Dyeing was performed under the same dyeing conditions as in Example 1, and samples were used for staining spots and texture evaluation. (1) Staining spots The dispersion of the dark and light staining areas was poor, and in some places the dark and light staining areas were clustered together, and there were areas where the difference in shade was band-like. In addition, variations among samples (n=5) were also observed. (2) Texture (a) Bulkyness Compared to the case of Example 2, the bulkiness was greatly reduced, shrinkage spots were present here and there, there were bulky spots, and the sample texture (n = 5) was also poor. Variations were seen. (b) Spun-like feeling Although there was a spun-like feeling, the tube-knitted surface had no unevenness, so the spun-like feeling was smaller than in Example 2. Comparative Example 3 Polyethylene terephthalate (containing 0.3% TiO ₂ as a matting agent) with an intrinsic viscosity of 0.64 was melted and further heated to 300°C, and then melted and heated to 300°C. (U.S. Patent No. 4349604)
It was discharged at a discharge rate of 37.5 g/min from the discharge hole described in . This discharge hole has a hole diameter of 0.15 mm and a land length of 0.30 mm.
A round hole 1 having a diameter of 0.27 mm and a land length of 1.3 mm are provided so that the center lines of both holes intersect at an angle of 5° directly below the spinneret surface. Further, the limit was that the discharge amount ratio and discharge speed ratio between the round holes 1 and 2 were 1.9 and 1.6, respectively. The PET flow discharged from this discharge hole is directly below the spinneret surface and is connected to the PET flow discharged from round hole 1 through round hole 2.
The PET flow discharged from the pipe wraps around the pipe, collides and vibrates, and joins. Subsequently, the joined PET stream was cooled and mixed and entangled in the same manner as in Example 1.
A multifilament of 75 de/36 fil was obtained by winding at a take-up speed of 4500 m/min. The properties of this multifilament are shown in Table 4.

[Table] Although the cross section of the filament constituting this multifilament was flat, it had a shape without a hollow part and the thickness unevenness in the longitudinal direction was small. The Worcester spots of this multifilament were small as shown in Figure 3b. next,
When this multifilament was knitted into a tube and dyed under the same conditions as in Example 1, it exhibited a certain degree of bulkiness. However, the robustness of such bulkiness is poor, and the bulkiness easily disappears by applying external force such as tension. This means that the shrinkage difference between and within the filaments of such a multifilament is small, and the shrinkage force of a multifilament made of such filaments is small. The number of entanglements in the multifilament thus obtained was 15/m, and the difference between the maximum shrinkage rate and the minimum shrinkage rate in the longitudinal direction was 15%. Comparative Example 4 The same procedure as Comparative Example 3 was carried out except that the spinning take-off speed was 3000 m/min and 36 entanglements/m were imparted by the fiber-mixing and entangling treatment. Next, this undrawn yarn was drawn and heat set under the drawing and heat setting conditions of Example 2 (however, the heat setting temperature was 180°C). Although the filaments constituting the multifilament thus obtained were flat, they had no hollow portions and had small unevenness in thickness in the longitudinal direction. Next, Table 5 shows the properties of this multifilament.

[Table] The number of entanglements of the drawn yarn was 23/m, and the difference between the maximum shrinkage rate and the minimum shrinkage rate was 10%. The sample obtained by dyeing the tubular knit using this multifilament under the same dyeing conditions as in Example 2 was
It had very little bulk, and had a paper-like texture, as if it had been knitted and dyed using flat yarn. This means that the shrinkage difference between and within the filaments of such a pulsing yarn is small, and the shrinkage force of a multifilament made of such filaments is small. Example 3 Spinning and stretching heat setting were carried out in the same manner as in Example 2, except that the dimensions of the discharge hole and the spinning take-off speed were changed as shown in Table 6 using the discharge hole shown in FIG.
I got 75de/36fil multifilament. The conditions for such stretching heat setting are also shown in Table 6. Further, Table 7 shows the motion state of collision and bounce of the polymer flow during spinning, the presence or absence of yarn breakage, and the properties of the obtained multifilament. Table 7 also shows the bulkiness of the samples obtained by dyeing the tubular knits using such multifilaments under the same dyeing conditions as in Example 1. As is clear from Tables 6 and 7, the present invention makes it easy to produce multifilaments that have a large shrinkage difference within and between filaments, a large shrinkage force, and have a good texture without staining spots. It turns out that you can get it.

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is a sectional view of a filament constituting the multifilament of the present invention, a side view in the longitudinal direction, and a front view rotated by 90 degrees from the side view, and a and b in FIG. and a graph showing the shrinkage rate in the longitudinal direction of a potentially bulky multifilament exhibiting shrinkage spots and staining spots, 3rd
Figures a and b are graphs showing Worcester spots of the multifilaments obtained in Example 1 and Comparative Example 3 and the conventional pulsing yarn, respectively, and Figure 4 is a cross-sectional view of the multifilament obtained by the present invention. , FIG. 5 is a multifilament stress (St)-elongation (E1) curve of the present invention, FIG. 6 is a sectional view of the discharge hole of the spinneret for obtaining the multifilament of the present invention, and FIG. 7 is a diagram of FIG. FIG. 3 shows perspective views (electron micrographs) of filaments (single fibers) cut along the cross section immediately after the polymer is discharged in free form from the discharge holes of a.

Claims (1)

[Claims] 1. A multifilament composed of filaments made of a melt-spun polymer,
The constituent filament is flat and has a pair of recesses facing each other across the long axis on the outer periphery in the long axis direction, and is asymmetrical with respect to the short axis existing between the pair of recesses. An eccentric hollow filament having a cross-sectional shape and a thickness unevenness in the longitudinal direction of the filament, the hollow portion being located on the side where the straight line parallel to the short axis is maximum in the cross section of the filament,
In addition, the degree of orientation of the hollow portion existing portion divided by the short axis is greater than the degree of orientation of the solid portion adjacent thereto, and mixed fiber entanglement is imparted between the constituent filaments. Potentially bulky multifilament. 2. The potentially bulky multifilament according to claim 1, wherein the filament has a substantially eyebrow-shaped cross-sectional shape and is asymmetrical with respect to the short axis. 3. A patent claim in which the filament has a substantially isosceles triangular cross-sectional shape, has a pair of recesses on opposing long sides, and is asymmetrical with respect to a short axis between the pair of recesses. The potentially bulky multifilament according to item 1. 4. The potentially bulky multifilament according to claim 1, wherein the solid portion is joined to the hollow portion without being wound around the hollow portion in the longitudinal direction of the filament. 5. The potentially bulky multifilament according to claim 1, wherein the filament at any cross section of the multifilament satisfies the following formula [ ]. n ₁ × m ₁ / n ₂ × m ₂ ≧1.5 ...[] [However, n ₁ × m ₁ and n ₂ × m ₂ are the long axis and short axis of each filament cross section in an arbitrary cross section of the multifilament. It is the product of the maximum straight line length parallel to , and shows the maximum and minimum values, respectively. ] 6. The potentially bulky multifilament according to claim 1, wherein the multifilament satisfies the following formula [ ]. L ₁ −L ₂ ≧20% ... [] [However, L ₁ indicates the final elongation at break of the multifilament, and L ₂ indicates the elongation when the maximum stress is exhibited. [7] The potentially bulky multifilament according to claim 1, wherein the number of entanglements in the multifilament is 10 pieces/m or more. 8. The potentially bulky multifilament according to claim 1, wherein the difference between the maximum shrinkage rate and the minimum shrinkage rate in the longitudinal direction of the multifilament is 35% or less. 9. The potentially bulky multifilament according to claim 1, wherein the melt-spun polymer is polyester. 10 A pair of discharge holes with different discharge cross-sectional areas are connected to each other by a slit, and the discharge hole with the larger discharge cross-sectional area is made into a hollow discharge hole with a hollow part formed by a plurality of slits, and the other discharge hole with the smaller discharge area is A molten polymer is discharged through the discharge hole of a spinneret having a single discharge hole, and at this time, the polymer flow discharged from the discharge hole with a larger discharge cross section among the pair of discharge holes is By making the discharge speed lower than that of the polymer flow discharged from the other discharge hole having a smaller discharge cross-sectional area, the high-speed polymer flow collides with the low-speed polymer flow, bounces and joins, and then A method for producing a potentially bulky multifilament, which comprises cooling and solidifying the material, subjecting it to a fiber-mixing and entangling treatment, and then taking it off. 11. The method for producing a potentially bulky multifilament according to claim 10, wherein the high-speed polymer flow is joined to the low-speed polymer flow without being entwined. 12. The method for producing a potentially bulky multifilament according to claim 10, wherein the arrangement of the plurality of slits constituting the hollow discharge hole and the cross-sectional shape of the single discharge hole are both circular. 13. The method for producing a potentially bulky multifilament according to claim 10, wherein the plurality of slits constituting the hollow discharge hole are arranged in a non-circular manner. 14. The method for producing a potentially bulky multifilament according to claim 10 or 13, wherein the plurality of slits constituting the hollow discharge hole are arranged in a triangular shape. 15. The method for producing a potentially bulky multifilament according to claim 10, which is a spinneret comprising a pair of discharge holes connected to each other by a slit. 16 Claim 10 or 15, in which the slit connecting the pair of discharge holes is single
A method for producing a potentially bulky multifilament as described in Section. 17 Claims in which the flow rate (v ₁ ) of the polymer stream discharged from the hollow discharge hole and the flow rate (v ₂ ) of the polymer stream discharged from the single discharge hole satisfy the following formula [] 2. A method for producing a potentially bulky multifilament according to item 1. 1/1.5≦v ₁ /v ₂ ≦1/7 …[] 18. The method for producing a potentially bulky multifilament according to claim 10, wherein the fiber-mixing and entangling treatment is performed using an interlace nozzle. 19. The method for producing a latent bulky multifilament according to claim 10 or claim 18, wherein the number of entanglements to be provided is 10 pieces/m or more. 20. The method for producing a potentially bulky multifilament according to claim 10, wherein the take-up speed is 2500 m/min or more. 21. The method for producing a latent bulky multifilament according to claim 10, which comprises cooling and solidifying the material and then taking it out and winding it up, or stretching it without winding it up. 22. The method for producing a latent bulky multifilament according to claim 10 or 21, wherein stretching is performed after the fiber-mixing and entangling treatment. 23. A method for producing a latent bulky multifilament according to claim 10, wherein the multifilament is wound at a speed of 4000 m/min or more without being drawn and stretched. 24. The method for producing a potentially bulky multifilament according to claim 10 or 17, wherein the polymer is polyester.