JPS61194205A - Production of slub yarn - Google Patents

Abstract

PURPOSE:To obtain a slub yarn having excellent distributing and contrast of the thick and thin parts of the yarn, by carrying out the melt-spinning under a specific condition using a spinneret having a pair of nozzles composed of a hollow nozzle and a single nozzle connected to the hollow nozzle by a slit. CONSTITUTION:A hollow nozzle composed of plural slits 1a-1c forming a hollow part is connected through a slit 3 to a single nozzle having smaller nozzle area than the hollow nozzle. In the melt-spinning of a polymer, the flow rate of the polymer extruded through the single nozzle is made higher than that of the polymer extruded through the hollow nozzle. The take-up speed can be set to <2,500m/min, the unevenness of the denier can be made high, and the distribution of the thick and thin parts can be made comparable to that of the yarn spun at a take-up speed of >2,500m/min.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing thick and thin yarn, and more particularly, to a method for producing thick and thin yarn in which thick and thin yarns are dispersed.

(Prior Art) Conventionally, thick and thin threads made of thermoplastic polymers, particularly polyethylene terephthalate thick and thin threads, have been mainly imparted with a drawing process.

That is, this is a method of producing thick and fine yarn by nonuniformly (low magnification) stretching undrawn yarn obtained at a spinning take-off speed of about 500 to 3,500 m 2 /min to generate stretching unevenness.

The ratio between the thick part and the detail of the thick and thin yarn obtained by this method (thickness ratio) is determined by selection of the spinning take-off speed of the undrawn yarn to be subjected to drawing, the drawing conditions (drawing ratio and drawing temperature), etc. . For example, spinning take-off speed 500-1000
Thick and thin yarns with a large thick-to-thin ratio can be obtained from undrawn yarns with a low birefringence (Δn) obtained at a spinning speed of 250 m/min.
From undrawn yarn with a relatively high Δn of 0 to 35 QOm/min, a thick/fine yarn with a small thick/fine ratio can be obtained.

However, a common drawback in all cases is that the thick portions and details of the obtained thick and thin yarn have poor dispersibility, and the thick portions and details tend to be unevenly distributed in the system.

Moreover, the thick parts of thick and thin yarns are dyed darkly, while the details are light dyed, so woven and knitted fabrics made of such thick and thin yarns generally have a spun-like look combined with marbled color effects. However, in woven or knitted fabrics that are made up of thick and thin yarns that are unevenly distributed in large areas and small areas, as mentioned above, dark dyed areas tend to appear in a band-like manner, and the texture is also hard. bawl.

In order to improve the dispersibility of such thick and thin threads,
Various manufacturing methods have been proposed in which stretching is carried out under a very narrow range of stretching conditions (see, for example, JP-A-49-54626 and JP-A-51-147616).

These manufacturing methods attempt to disperse the stretching points as much as possible during stretching, but since the stretching points tend to concentrate even with the slightest impact, it is difficult to maintain the stretching points in a dispersed state. It is extremely difficult.

For this reason, there is a limit to the ability to industrially obtain thick and thin yarns in which thick and thin fibers are dispersed by improving the drawing conditions.

On the other hand, the present inventors proposed a method for producing thick and thin yarns that can be formed into thick and thin yarns in the spinning process in Japanese Patent Application No. 59-5699 and Japanese Patent Application No. 36097-1987.

This manufacturing method has a flow velocity difference from a pair of discharge holes, in which a hollow discharge hole whose hollow portion is formed by a plurality of slits and a single discharge hole whose discharge cross-sectional area is smaller than that of the hollow discharge hole are connected by a slit. A pair of polymer streams are discharged, and the high-speed polymer stream discharged from a single discharge hole collides and bounces with the low-speed polymer stream discharged from a hollow discharge hole to join them, and then is cooled and solidified at a rate of 2500 m/min. This is what you will receive.

The filaments constituting the thick and thin yarn obtained by this method have a difference in degree of orientation in the cross-sectional direction and are also thick and thin in the longitudinal direction.

Thick and thin yarns made of such filaments have good dispersibility of thick and thin filaments, and can also exhibit sufficient bulk through heat treatment and can exhibit a spun-like texture, but the difference in dyeing shading based on thick and thin filaments Since the contrast (hereinafter sometimes referred to as "contrast") is somewhat insufficient compared to thick and thin yarns obtained by conventional non-uniform stretching, improvements in this point are desired.

(Objective of the Invention) The object of the present invention is to solve the aforementioned drawback, that is, the lack of contrast due to thick and fine yarns, in a method for producing thick and fine yarns that can form thick and fine yarns in a spinning process, and to disperse the thick and fine yarns. It is an object of the present invention to provide a method for producing a thick and thin yarn that can obtain a thick and thin yarn with good properties and contrast.

(Structure) As a result of studies to achieve the above object, the present inventors found that the thick/fine ratio of the obtained thick/fine yarn is largely influenced by the spinning take-off speed.
By reducing the take-up speed to less than 2500 m/min,
The present invention was achieved by discovering that the thick-to-thin ratio increases rapidly and the dispersibility of the thick-to-thin ratio is comparable to that in the case of take-up speed of 25,007 FL/minute yield.

That is, the present invention provides a pair of hollow discharge holes having a hollow portion formed by a plurality of slits and a single discharge hole having a discharge cross-sectional area smaller than the discharge cross-sectional area of the hollow discharge hole, which are connected by a slit. discharging molten polymer through a spinneret having discharge holes, with the polymer stream from the single discharge hole having a higher velocity than that from the hollow discharge hole;
The former polymer stream is collided with and bound to the latter polymer stream under the surface of the spinneret and joined together, then cooled and solidified, taken off at a speed of less than 2500 m / min, and then subjected to stretching heat treatment. This is a method for producing thick and thin thread.

The present invention will be explained with reference to the drawings.

Figure 1 is a sectional view of the discharge hole of the spinneret used in the present invention, Figure 2 is a sectional view of the discharge hole of the spinneret used in the present invention,
The figure shows the spinning take-off speed and the Worcester spot (U) of the thick and fine yarn obtained.
%), FIG. 3 is a cross-sectional view of filaments constituting the thick and thin yarn obtained by the production method of the present invention, and FIG. 4 is a graph showing the longitudinal direction of the filaments constituting the thick and thin yarn obtained by the present invention. 5 is a cross-sectional view of the thick and thin yarn obtained by the present invention, and FIG. 6 (mountain a) is the thick and thin yarn obtained by the present invention and the thick and thin yarn obtained by conventional non-uniform stretching. Stress (St)-elongation (EL) curves are shown, respectively.

In FIG. 1, 18 to 1c and 2.3 are discharge holes for discharging the polymer flow, 4 is a hollow portion formed by a plurality of slits indicated by 18 to 1C, and 2 is a single discharge hole. ,
3 is a hollow discharge hole consisting of slits 1a to 1C and a hollow part (4), and a slit connecting the single discharge hole (2), J
IAz is the inner diameter of the single discharge hole, l and W are the slits (3)
The width and length, JIA+ and uB+ respectively indicate the outer diameter and inner diameter of the hollow discharge hole in FIG. 1 (ω).

In the present invention, it is important to employ the discharge hole shown in FIG. 1 as the discharge hole for discharging the molten polymer.

The feature of such a discharge hole is that, as a pair of discharge holes with different discharge cross-sectional areas, a hollow discharge hole composed of a plurality of slits (1a to IC) is formed in the discharge hole with a large discharge cross-sectional area, and a hollow discharge hole is formed in the discharge hole with a large discharge cross-sectional area. This is because a single discharge hole (2) is used for each of the small discharge holes, and the hollow discharge hole and the single discharge hole (2) are connected by a slit (3).

In 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 resulting polymer streams by colliding and bouncing, then cooling and solidifying them before taking them off at a speed of less than 2500 m/min.

Here, in the discharge holes shown in FIG. 1, if the total discharge cross-sectional area (S1) of the slits (18 to 1c> of the hollow discharge holes) and the discharge cross-sectional area (S1) of the single discharge hole (2) are made equal,
Collision and bouncing of the polymer flow directly under the spinneret become so intense that stable spinning becomes difficult.

In addition, the hollow discharge hole and the single discharge hole (2) are connected to the slit (3).
) If unconnected discharge holes are used, the collision and bounding of the polymer flow discharged from both ridge holes will be extremely small, or the collision and bounding will not occur, resulting in a thick and fine yarn. There is no thick/thin ratio at all, or even if it does exist, the ratio is extremely small.

Furthermore, even when the spinning take-off speed is set to 2500 m 2 /min., it is not possible to sufficiently increase the thick-to-fine ratio of the obtained yarn.

This is shown in FIG. Figure 2 shows a 75de/36 yarn in which undrawn yarn was obtained by variously changing the spinning take-off speed using the discharge hole shown in Figure 1 (ω), and then subjected to the drawing heat treatment described below.
Measure the Worcester spot (U%) of the drawn yarn of f i l,
The results are plotted.

The U% is measured using a Worcester Evenness Tester Model C manufactured by Zellweger Worcester, and indicates that the greater the U%, the greater the ratio of thick and thin yarns.

As is clear from FIG. 2, when the spinning take-off speed is less than 2,500 m/min (preferably 2,000 to 1,500 m/min), the U% of the obtained drawn yarn increases rapidly.

Next, in the present invention, the undrawn yarn obtained in this way is
Since it cannot be put to practical use as it is, it is necessary to further perform a stretching heat treatment.

For such drawing heat treatment, the drawing conditions that are used when producing conventional thick and thin yarns can be adopted, but the drawing conditions that are used when obtaining ordinary drawn yarns can be used during drawing. This is preferable because the occurrence of yarn breakage and fuzz can be reduced.

In this way, even if the drawing conditions for obtaining normal drawn yarn are adopted,
It is also one of the features of the present invention that thick and thin threads with good thick and thin dispersibility can be obtained.

The arrangement shape of the slits of the hollow discharge holes and the cross-sectional shape of the single discharge hole employed in the present invention do not need to be particularly limited, and the optimum shape may be adopted depending on the purpose.

For example, as the arrangement shape of the slits of the hollow discharge hole, the non-circular shape described in British Patent No. 853,062 can be adopted, and among them, the shape shown in FIG.

The cross-sectional shape of the thick and thin filaments obtained in the triangular arrangement shown in can be made into a substantially isosceles triangular shape, which is preferable because it can impart a unique luster.

Further, it is preferable that the slit array shape of the hollow discharge hole and the cross-sectional shape of the single discharge hole be circular as shown in FIG. 1 (ω) because the machining is easy.

Furthermore, in FIG. 1, surprisingly, by connecting the single discharge hole (2) and the hollow discharge hole with a single slit (3), the polymer flow discharged from the single discharge hole (2) is It is preferable that the polymer flow is bonded while colliding and bouncing on one side of the polymer flow discharged from the hollow discharge hole, so that a large thickness can be imparted to the filaments constituting the obtained thick and thin thread in the longitudinal direction.

The shape of the slit (3) is not limited to the straight shape shown in FIG. 1, but may also be hook-shaped or curved. The point is that the hollow discharge hole and the single discharge hole (2) are connected by a slit.

In addition, by setting the length 1 of the slit (3) so that a concave portion is formed in the cross section of the obtained filament, both polymer flows discharged from the hollow discharge hole and the single discharge hole (2) can be The vibration period due to collision and bouncing can be increased, and the obtained filament can be given an extremely large thickness in the longitudinal direction. Note that the discharge hole adopted in the present invention is a single discharge hole (a) shown in FIG.
may be connected to one or more hollow discharge holes, and the shape of a single discharge hole (a may also be non-circular such as a triangle, square, or 7-shape).

The specific dimensions of the discharge hole used in the present invention described above are shown below for the discharge hole of FIG. 1 (ω).

1.5≦81/S2≦15 0.04≦(Standing A+ Once B+)/2≦0.300.1
0≦Text A2 <uB+ <lA+≦1.5 0.05≦Polish≦ 1.30 0.03≦W Cross A2≦ 1.0 [However, fiA+, uB+, uA2. The unit of each of imperial and W is (as). ] At this time, between a pair of discharge holes that discharge the molten polymer, the discharge cross-sectional area ratio (S+/Sz )as well as/
Alternatively, it is preferable that the lengths of the slits (3) are different. This is because it is possible to further improve the dispersibility of filament fragments whose collision and bounce periods of the discharged polymer stream are substantially different.

Further, in the production method of the present invention, the discharge speed ratio between the flow velocity (v1) of the polymer flow discharged from the hollow discharge hole and the flow velocity (v1) of the polymer flow discharged from the single discharge hole (2) (V
+ / V2) to 1/1.5 to 1/7, especially 1/
It is preferable to set it to 2.3 to 1/3.4, and the polymer discharge rate ratio [discharge rate of hollow discharge hole/discharge ffi of single discharge hole (2)] at this time is 3/1 to 115. , especially 1.
It is preferable to set it to 5/1 to 1/3.3.

In this way, in the present invention, the discharged and joined polymer flow is
Cooled and solidified and collected at less than 25,007 FL/min.
Furthermore, a stretching heat treatment is performed. This drawing heat treatment can be carried out either by winding up the undrawn yarn obtained by melt spinning and then subjecting it to drawing heat treatment in a separate process, or by continuously drawing and heat treating the obtained undrawn yarn without winding up one batch. may be applied.

Incidentally, the undrawn yarn before drawing may be interlaced with an interlacing device or the like, and then drawn.
This is preferable because it can further improve the dispersibility of the obtained thick and thin threads.

The filaments constituting the thick and thin yarn obtained by the present invention are flat hollow filaments having the cross-sectional shape shown in FIG. The polymer flow discharged from the single discharge hole (2) is divided at the joint where the degree of orientation of the hollow portion existing portion is greater than the degree of orientation of the adjacent solid portion, and the degree of orientation is greater in the longitudinal direction. It also has thick and thin parts as shown in FIG.

In Fig. 2, Fig. 2 (ω(b+) is respectively Fig. 1 (ω(
b) shows the cross-sectional shape of the filament obtained using the discharge hole, n in the figure is the long axis, C is the short axis, x and x' are a pair of convexes facing each other with the long axis (n) in between. Department.

C is the hollow part, and l is the length of the straight line that shows the maximum value among the straight lines parallel to the minor axis (C) in the cross section of the filament.

Q is a hollow part divided by the short axis (C) in the cross section including the hollow part (e), h is a solid part also divided by the short axis (C), and the cross-sectional area of the part g is h It is always greater than that of its parts.

A pair of recesses indicated by x and x' in FIG. 3 are joints where the polymer flow discharged from the hollow discharge hole in FIG. Department.

Also, the 41st! In I, (a) shows a perspective view in the longitudinal direction of the filament obtained by the present invention, and crests) show a perspective view in the longitudinal direction of the filament with ω rotated by 90 degrees. Indicates the thick and thin spacing.

As is clear from FIG. 4, the thick and thin filament in the longitudinal direction obtained by the present invention has a cross-sectional area of 6 in the longitudinal direction.
They are joined while changing greatly compared to the cross-sectional area of the parts.

Further, the thick and thin intervals (L-0, 3 to 3 m) in the longitudinal direction of the filaments constituting the thick and thin yarn obtained by the present invention exist randomly, and even in an arbitrary cross section of the thick and thin yarn made of such filaments, As shown in FIG. 5, the dispersibility of thick and thin particles is good.

In FIG. 5, A indicates a filament cross section which is the maximum cross-sectional area of one multifilament cross section, and nl and 11 indicate the long axis and maximum linear length of the filament cross section (A), respectively. Further, B'' indicates the filament cross section with the minimum cross-sectional area in one multifilament cross section shown in FIG. 5, and nl and -2 indicate the long axis and maximum linear length of the filament cross section (B), respectively.

Here, thick and thin yarns in which the filament (A) and the filament (B) satisfy the following formula [I1] are preferable because the contrast based on the difference in dyeing shading can be sufficiently increased.

(ns X It) / (nz X lz)≧3
．． 5-[I[] Furthermore, the stress (St) of such thick and thin threads-
The elongation (EL) curve is similar to that shown in Figure 6 (ω).

On the other hand, the stress (St)-elongation 11 [(EL) curve (hereinafter referred to as
(sometimes referred to as the elongation curve) is shown in FIG. 6(b).

In FIG. 6, Ll indicates the final elongation at break, and L2 indicates the elongation at maximum stress.

Moreover, in FIG. 6 (to), A shows the elongation crystal line of the detail (stretched part), and the opening shows the elongation curve of the thick part (unstretched part).

In this way, in the elongation curve of the conventional thick and thin yarn shown in FIG. 6 (b+), the thick part and the details are clearly separated, but With fine threads, the bulk and details cannot be separated.

This also indicates that the thick and thin yarn obtained by the present invention has extremely better dispersibility of thick and thin yarn than conventional thick and thin yarns.

In addition, in FIG. 6(a), the (L+ -12)(7) value is 5% or more.

The denier of the thick and fine filament obtained by the present invention is 0.
．． 5-8 de, especially 1.0-5. Ode, and the total denier is 30 to 200 de, especially 40 to 150 de.
It is preferable from the viewpoint of texture.

In addition, the target polymer of the present invention is polyethylene terephthalate, in which 85 mol% or more of the repeating units are substantially ethylene terephthalate, and the polymer has various properties such as matting, improved dyeability, antistatic properties, etc. The desired additive substance may be included as a copolymer or a blend. Intrinsic viscosity of polyethylene terephthalate (35℃
(measured in orthochlorophenol) from 0.45 to 1.
20 is preferable, and 0.50 to 1.00 is particularly preferable.

When the intrinsic viscosity is less than 0.45, the strength level of the obtained thick and thin yarn is unfavorably low. In addition, the intrinsic viscosity is 1.2
When it exceeds 0, the melt viscosity during spinning is too high and it is necessary to lower 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) In general, if the flow velocity of the polymer flow passing through each slit making up the hollow discharge hole and a single discharge hole is equal to each other, the total pressure loss of the multiple slits in the hollow discharge hole is equal to It is larger than the discharge hole.

In this regard, the discharge hole shown in FIG. 1 adopted in the present invention has both a hollow discharge hole and a single discharge hole (2) in the same discharge hole through the slit (3). A flow velocity difference is created between the polymer streams passing through both holes so that the pressure drop across the holes is equal. Therefore, by adjusting the slit width of the hollow discharge hole, the inner diameter (fAz) of the single discharge hole (2), etc.,
Single discharge hole (
2) It is possible to provide a flow velocity difference so that the flow velocity of the polymer stream discharged from the polymer flow becomes faster, and to easily increase the flow velocity difference.

In this way, the flow speeds of the polymer streams 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). Since the polymer flow discharged from the hollow discharge hole collides and bounces with the polymer flow discharged from the single discharge hole (2), the polymer flow is made thick and thin in the longitudinal direction as shown in Fig. 4. Thus, a filament having the following properties is obtained.

The number and size of such thick and thin filaments per unit length depend on the spinning take-off speed.
As a result of setting the speed to less than 00 m 2 /min, large thick and thin patterns can be randomly applied.

Furthermore, since the flow rate of the polymer flow passing through the slits (1a to 1cJ) of the hollow discharge holes is slower than that of the polymer flow passing through the single discharge hole (2), the spinning draft is ) is mainly concentrated in the polymer flow discharged from the hole.For this reason, the hollow portion formed by such a polymer flow is subjected to a larger shear force than when the hollow discharge hole is a single discharge hole, and the polymer flow is This results in a higher degree of orientation than if it were solid.

In addition, the discharge cross-sectional area (S1) of the single discharge hole ('2J) is the total discharge cross-sectional area (S1) of the slits (la~1) of the hollow discharge hole.
), so in the filament cross section obtained, the cross-sectional area on the i-side including the hollow portion is smaller than the cross-sectional area on the i-side.

In the cross-section of the filament obtained in this way, as shown in FIG. 3, the g portion, which has a larger cross-sectional area including the hollow portion +e) than the h portion, has a higher degree of orientation than the h portion.

The thick and thin yarn formed from such filaments has a larger ratio of thick and thin yarns than the thick and thin yarn obtained at a spinning speed of 2500 m/fiber separation, and the contrast based on the thick and thin fibers can be sufficiently satisfied. It is something.

Moreover, the thick and thin yarn obtained by the present invention has better dispersibility in thick and thin yarn than the thick and thin yarn obtained by conventional non-uniform drawing, and is made from filaments that have a shrinkage difference in the cross-sectional direction of the filament. Therefore, sufficient bulkiness can also be provided by heat treatment.

(Effects of the Invention) According to the present invention, like the conventional non-uniform stretching method, the stretching process is controlled (for example, the aging of undrawn yarn).

It is industrially suitable because it does not require strict stretching ratio, etc.

Furthermore, the R-knitted fabric using the thick and thin yarn obtained by the present invention is spun-like with a large "bulge" and a natural appearance.

(Example) The present invention will be further explained below with reference to Examples, and the physical properties used in the Examples were measured by the following method.

(1) nl, Ill, and nl, m2
Take a cross-sectional photograph of an arbitrary cross-section of a thick and thin thread at a magnification of 560 parts, and the hollow part is determined by the long axis (n1) and maximum linear length (1+) of the filament cross-section where the cross-sectional area is maximum, and where the cross-sectional area is The long axis (n1) and the maximum linear length (12) of the minimum filament cross section were actually measured.

(2) Elongation at maximum stress (L1) and elongation at near-terminal failure [I(L+)] In a normal tensile tester, in a greenhouse at 25°C and at a temperature of 60%
Then, calculate the stress-elongation curve under the conditions of sample length Iocm and tensile speed 200aII/M, and find the elongation at which the stress is maximum (
L1), and the elongation at which the stress became zero was defined as the final elongation at break (L1).

(3) Make a “skein” of shrinkage rate multifilament and apply 2. When a load equivalent to OIIIg/de was applied and the sample was treated in boiling water for 30 minutes, the shrinkage rate was determined from the following formula.

[(Jlo - polish+)/uo] X 100(%
) = Shrinkage rate (%) Sentence. : Length of "skein" before treatment 1 : Length of "skein" after treatment 4) Thick and thin multifilament with thick and thin (Ll light) dispersibility and contrast obtained is cylindrically knitted and dyed with disperse dye. After dyeing using the method, the sample was washed with water, dried, and set at 180° C. for 1 minute before being used as an evaluation sample.

(ω Dispersibility The above sample (103 x 10 cm) was evaluated by measuring the length of the darkly dyed part. (Usable range Δ or more) ○: All lengths of II dyed part are less than 0.5α .

Δ: The length of the eastern part of Il is 0.5011 to 1.0Q11.

×: The length of the darkly dyed portion exceeds j, QcIR.

The tube knitting dyeing conditions are as follows: Dye: Polyester E as
tn+an B Iue dye ratio: 4% based on the tube knitting weight Auxiliary agent: Monogen (0.5%/again) Bath ratio: 1/100 Temperature x Time: 100°C x 60 minutes (ω Contrast for the above sample, visually Contrast between light and shade was evaluated. (Usable range Δ or more) O: The dark dyed area is distinct from the light dyed area.

Δ: A pattern of darkly dyed areas and lightly dyed areas exists but is unclear.

×: In the case of tube knitting, it appears that there are no darkly dyed areas and light dyed areas.

[Example] Polyethylene terephthalate with an intrinsic viscosity [η] of 0.64 (contains 0.3fli amount of Ti 02 as a matting agent)
was melted and spun at a spinning temperature of 300° C. and discharged from the discharge hole shown in FIG.

1500m/min, 2000m/min, 2600m/min
The yarn was wound at a speed of 3,000 m/min, and then subjected to drawing heat treatment to obtain a drawn yarn of 75 de/36 fil. The dimensions of the discharge holes used are shown in Table 1, and the discharge volume and
Stretching ratio.

Table 2 also shows the basic physical properties of the obtained thick and thin thread.

(Margin below) Table 1 Table 2 This comparative example Note that the stretching heat treatment conditions are as follows.

[Stretching heat treatment conditions] Preheating temperature: 80°C Heat treatment temperature: 240°C (slit heater temperature) Drawing speed: 700 m/min The stress-elongation curves of the thick and thin yarn shown in Table 2 are all shown in Figure 6 (ω). there were.

Next, the samples shown in Table 2 were dyed in a tube knitting manner according to a conventional method, and the dispersibility and contrast of shading were investigated.

The results are shown in Table 3.

(Margins below) Table 3 This Comparative Example As shown above, when the take-up speed exceeds 2500 m/min, the dispersibility is good but the contrast of shading is weak; Both dispersibility and contrast were good.

[Comparative Example] Polyethylene terephthalate having an intrinsic viscosity [η] of 0.64 was molten from a spinneret in which 36 round holes with a pore diameter of 0.30 iww were arranged (Ti 02 was added as a matting agent to 0.64 mm).
(containing 3% by weight) was wound at a discharge rate of 27.59/sin and a spinning take-off speed of 1500 m/min. This undrawn yarn was subjected to non-uniform stretching under the following stretching conditions.
A thick and thin thread of /36fil was obtained.

(Stretching conditions) Preheating temperature 60°C Heat treatment temperature 240°C (Slit heater temperature) Stretching ratio 2.20 Stretching speed* 700 m/min The stress-elongation curve of the obtained thick and thin yarn is shown in Figure 6(b). The major part and the detail were clearly separated. The basic physical properties of this thick and thin thread are shown in Table 4.

Table 4 (blank below) Next, this thick and thin yarn was dyed in a tube-knitted manner in the same manner as in Examples, and the dispersibility and contrast of shading were investigated.

As a result, the contrast between light and shade was sufficiently large and good, but there were strips with lengths of 1.0 cm or more, and the dispersibility was poor.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the discharge hole of the spinneret used in the present invention, Figure 2 is a sectional view of the discharge hole of the spinneret used in the present invention,
The figure shows the spinning take-off speed and the Worcester spot (0
%), FIG. 3 is a cross-sectional view of filaments constituting the thick and thin yarn obtained by the production method of the present invention, and FIG. 4 is a graph showing the longitudinal direction of the filaments constituting the thick and thin yarn obtained by the present invention. FIG. 5 is a cross-sectional view of the thick and thin yarn obtained by the present invention, and FIG. The stress-elongation curves of the threads are shown respectively. (b)

Claims (1)

[Claims] (1) A hollow discharge hole whose hollow portion is formed by a plurality of slits and a single discharge hole having a discharge cross-sectional area smaller than the discharge cross-sectional area of the hollow discharge hole are connected by a slit. By discharging the molten polymer through a spinneret in which a pair of discharge holes is arranged, the flow rate of the polymer stream from the single discharge hole being higher than that from the hollow discharge hole. , the former polymer stream is collided with and bound to the latter polymer stream under the surface of the spinneret, and is then cooled and solidified, then taken off at a speed of less than 2500 m/min, and then subjected to a stretching heat treatment. Characteristic manufacturing method for thick and thin yarn. (2) The method for producing thick and thin yarn according to claim (1), 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. (3) The method for producing a thick and thin thread according to claim (1), wherein the plurality of slits constituting the hollow discharge hole are arranged in a non-circular manner. (4) The method for producing thick and thin yarn according to claim (1) or (3), wherein the plurality of slits constituting the hollow discharge hole are arranged in a triangular shape. (5) The method for producing thick and thin yarn according to claim (1), wherein the spinneret is comprised of a pair of discharge holes communicated with each other by a slit. (6) The method for producing thick and thin yarn according to claim (1) or (5), wherein there is a single slit that connects the pair of discharge holes to each other. (7) Flow velocity of the polymer flow discharged from the hollow discharge hole (v_
1) and the flow rate (v
_2) is a flow rate that satisfies the following formula [I], the method for producing thick and thin yarn according to claim (1). 1/1.5≦V_1/V_2≦1/7・・・・・・［
I ] (8) After cooling and solidifying, take it out and roll it up, or
Alternatively, the method for producing thick and thin yarn according to claim (1), wherein the yarn is stretched without being wound up once. (9) The method for producing thick and thin yarn according to claim (1), wherein the polymer stream is polyester.