JPH1150329A - Melt spinning of eccentric conjugate fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a melt spinning method capable of providing a conjugate fiber obtained by eccentrically joining two kinds of polymer having large difference of melt viscosity under stable spinning conditions. SOLUTION: Eccentric conjugate fiber obtained by eccentrically joining two kinds of polymers having 500-4,000 poise difference of melt viscosity in melt spinning temperature is melt spun by using a spinneret having shape continuously enlarging cross section of discharge hole and having discharge hole satisfying the following items (1) to (3): (1) Cross section SA of point A where cross section of discharge hole starts enlargement is 0.0314 to 0.7850 mm<2> , (2) cross section SB of point B where cross section of discharge hole becomes maximum is >=3.142 mm<2> and (3) angle θ at which discharge hole continuously enlarges is 10-45 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for melt-spinning an eccentric conjugate fiber in which two kinds of polymers having a difference in melt viscosity are eccentrically joined, for example, having a latent crimp developing ability. More particularly, the present invention relates to a method for melt spinning an eccentric conjugate fiber in which kneeling of a yarn discharged from a discharge hole is remarkably suppressed and spinning can be performed extremely stably.

[0002]

2. Description of the Related Art When an eccentric conjugate fiber such as an eccentric core-sheath type or a side-by-side type is melt-spun from two types of polymers having a difference in melt viscosity, the yarn discharged from a discharge hole is subjected to the difference in melt viscosity. Due to this, it is easy to cause kneeling, and it is difficult to stably perform melt spinning particularly when the difference in melt viscosity is large.

Conventionally, in order to solve such a problem, a method of adding a thickener to a low melt viscosity side polymer or a thickener to a high melt viscosity side polymer, a method of adding a low melt viscosity side polymer to a high melt viscosity side polymer, and the like. A method in which the discharge linear velocities of the two are made uniform by joining the polymer flow from the side (for example, see Japanese Patent Application Laid-Open No. 2-27).
No. 7821) has been proposed.

[0004] However, the method of adding a thickener or a thickener to a polymer often causes coloring or decomposition of the polymer by these agents, which is problematic depending on the application. On the other hand, the method of joining the low melt viscosity side polymer to the high melt viscosity side polymer flow from the side has the effect of suppressing the kneeling, but the effect is still insufficient, and the foreign matter around the discharge hole (the foreign matter on the cap surface) (Sometimes referred to as), resulting in problems such as deterioration of spinning condition and deterioration of the quality of the obtained fiber.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a melt-spinning method which can produce a composite fiber in which two polymers having a difference in melt viscosity are eccentrically joined under an extremely stable spinning condition. The aim is to provide a method.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have set the spinning draft to 1000 or more, preferably 3000 or more, and to reduce the back pressure of the polymer flow in the discharge hole. It has been found that the above object can be achieved if a stable flow is formed by suppressing the flow, and the present invention has been achieved.

That is, according to the present invention, the melt viscosity difference at the melt spinning temperature is 500 to 4000 poise.
When melt-spinning an eccentric conjugate fiber to which a kind of polymer is bonded, a discharge hole having a shape in which a discharge cross-sectional area is continuously increased, and the discharge hole simultaneously satisfies the following (1) to (3). A method for melt spinning an eccentric conjugate fiber using a spinneret is provided. (1) Cross-sectional area S at point A where the cross-sectional area of the discharge hole starts to expand
_A is 0.0314~0.7850mm ^{2 (2)} discharge Anadan area cross-sectional area S _B of the point B to the maximum 3.142Mm ² or more (3) the angle θ is 10 to the discharge hole is enlarged continuously 45 ゜

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The eccentric conjugate fiber to which the present invention is applied is not limited as long as the two types of polymers are conjugated so that their respective centers of gravity are different from each other. For example, eccentric core-sheath type composite fibers, side-by-side type composite fibers, and the like can be given. Among them, the side-by-side type conjugate fiber is preferable because the effect of suppressing the kneeling, which is the object of the present invention, is particularly large.

[0009] The melt viscosity difference at the melt spinning temperature of the two polymers constituting such a conjugate fiber must be 500 to 4000 poise, preferably 1000 to 3000 poise. When the difference in melt viscosity is less than 500 poise, the yarn discharged from the discharge hole is hard to be kneaded, so that it can be manufactured sufficiently stably with a conventional spinneret and is out of the scope of the present invention. . On the other hand, if it exceeds 4000 poise, it is not preferable because the use of a spinneret described later cannot sufficiently suppress the kneeling.

The polymer which can be used in the present invention is not particularly limited as long as it satisfies the above-mentioned requirement of the melt viscosity difference, and any of polyester, polyamide, polyolefin and the like can be used. Among them, a combination of polymers of the same type, such as polyesters, is preferable because adhesion at a bonding interface is good and thread breakage hardly occurs. Combinations of polyethylene terephthalate-based polyesters of .about.0.5 are preferred.

In the present invention, in spinning the eccentric conjugate fiber by combining the above-mentioned polymers, a spinneret having a discharge hole whose cross-sectional area is continuously increased as shown in FIG. 1 is used. It is important to do it. Of course, as long as the laminar flow state of the polymer is not disturbed, it may be expanded stepwise. Looking at the cross-sectional area of the discharge hole, characterized becomes maximum at a point 3 continuously expanded molten polymer from the cross-sectional area S _A at the point 2 which is the end point of the polymer introducing section 1 leaves the discharge hole This is a point that is significantly different from the usual discharge holes used conventionally.

In general, the spinning draft depends on the cross-sectional area of the discharge hole at the point where the molten polymer is discharged. For example, in the case of the discharge hole shown in FIG. Since the hole diameters of 2 ′ and 3 ′ are the same, if the hole diameter is too large, the back pressure of the polymer becomes insufficient, the state of the polymer flow becomes unstable, and discharge unevenness occurs, so the discharge hole diameter is increased. There were limitations.

On the other hand, in the case of the discharge hole as shown in FIG. 1 according to the present invention, since a large back pressure is first applied by squeezing at the point 2 and then gradually expanded, the back pressure between the point 2 and the point 3 is increased. Changes very smoothly and continuously, and the velocity of the polymer stream also decreases continuously. Therefore, as compared with the discharge hole as shown in FIG. 2, the degree even under back pressure decrease by increasing the discharge Anadan area S _B at the point 3 becomes extremely small, to stabilize the flow of the polymer at a very low state You can do it.

That is, the present invention provides an apparent spinning draft of at least 1,000, preferably at least 3,000,
Particularly preferably, by using a spinneret capable of being 6000 or more, the linear velocity of the polymer flow discharged from the discharge hole is reduced and the elongation deformation is increased,
By doing so, the kneading of the melt-ejected yarn caused by the difference in melt viscosity between the two polymers is suppressed.

In order to achieve to such a kneel inhibitory effect satisfactory level, the cross-sectional area S _A at the point 2 in FIG. 1, the cross-sectional area S _B at the point 3, further taper angle θ is above (1) (3) must be satisfied at the same time.

That is, the cross-sectional area S _A is 0.0314-
0.7850 mm ² (round hole equivalent 0.2 to 1.0 mm
Diameter), preferably within a range of 0.071 to 0.283 mm ² (0.3 to 0.6 mm diameter in terms of a round hole).
The cross-sectional area S _A is 0.0314 mm ² (round hole equivalent 0.2 mm
If the diameter is less than (diameter), the throttle at the point 2 becomes extremely large, which is preferable from the viewpoint of increasing the back pressure. However, it is not preferable because clogging is easily caused by foreign matter and the composite structure is easily disturbed. On the other hand, the cross-sectional area S _A is 0.7850
If it exceeds mm ² (diameter of 1.0 mm in terms of a round hole), it is not preferable because the drawing effect becomes insufficient and a stable polymer flow cannot be obtained.

[0017] Then the cross-sectional area S _B is, 3.142mm ² (circular hole in terms of 2.0mm diameter) or more, preferably 7.065mm
² (diameter of round hole: 3.0 mm) or more. Sectional area S _B is not affect the polymer flow rate and spinning draft at the point 3 where the molten polymer leaves the discharge hole, the cross-sectional area S _B is 3.142mm ² (circular hole in terms of 2.0m
When the diameter is less than m), the polymer flow velocity does not decrease sufficiently and the spinning draft does not increase sufficiently. Therefore, it is possible to suppress the kneeling when two polymers having a large difference in melt viscosity are discharged eccentrically. become unable. Cross-sectional area S
The upper limit of _B is not necessarily limited, but if it is too large, the discharge hole cross-sectional area per hole becomes large, so that the number of holes cannot be increased,
Further, since it becomes difficult to control the composite form of the composite fiber, it is preferable that the diameter be 113 mm ² (12.0 mm diameter in terms of a round hole) or less.

Further, what is important in the spinneret used in the present invention is to set the taper angle θ which continuously increases to a specific range. That is, the taper angle θ needs to be 10 to 45 °, preferably 15 to 35 °.

If the taper angle θ is less than 10 °, the pressure during extrusion becomes too large, and the thickness of the die itself becomes extremely large, which is not preferable in terms of practicality and operability. On the other hand, if it exceeds 40 °, the polymer flow at points 2 and 3 becomes extremely unstable, which not only deteriorates the stability of the composite form but also greatly reduces the spinnability, which is not preferable.

The cross-sectional shape of the discharge hole is not necessarily limited to a round hole, but may be applied to various shapes, for example, irregular discharge holes such as a triangular hole and a hexagonal hole, and hollow discharge holes having a hollow forming ability. Needless to say.

The discharge hole in the present invention is characterized in that it is greatly constricted at the point 2. However, due to the manufacturing of the base, the cross-sectional area near the point 2 is the same, and then the discharge hole expands. The object of the present invention can be achieved even by using such a discharge hole.

In producing an eccentric conjugate fiber in which two kinds of polymers are joined eccentrically using the above-mentioned spinneret, conventionally known production equipment and production conditions may be appropriately selected and set. .

[0023]

EXAMPLES The present invention will be described below more specifically with reference to examples. In addition, each physical property in this example was measured by the following method.

<Intrinsic Viscosity> The intrinsic viscosity was measured at 35 ° C. using orthochlorophenol as a solvent.

<Spinning condition> Winding time 2.5 hours (winding amount about 7K
In g), the ratio of the occurrence of yarn breakage (number of yarn breakage / number of yarn hooking) was measured and expressed as a percentage.

<U%> 3000 r / m at a supply speed of 100 m / min using Evenness Tester (manufactured by USTER).
The sample was supplied to the detection end while applying a twist, and the measurement was performed.

[Examples 1 and 2, Comparative Examples 1 and 2] Polyethylene terephthalates having intrinsic viscosities of 0.64 and 0.36 were melted at 280 ° C., respectively, and formed into a shape as shown in FIG. The spinning temperature is 280 ° C. (the melt viscosity of the former is 1120 poise, the melt viscosity of the latter is 120 poise) from the spinneret (discharge hole 24) having the discharge holes of
It was extruded at a rate of 1450 m / min at a rate of g / min (composite weight ratio 1/1), drawn at a rate of 3.2 times, and obtained as a side-by-side type composite fiber (100 denier / 24 filaments). The results are summarized in Table 4.

[0028]

[Table 1]

[Examples 3 and 4, Comparative Examples 3 and 4] Polyethylene terephthalates having intrinsic viscosities of 0.74 and 0.36 were melted at 290 ° C., respectively, and formed into a shape as shown in FIG. The spinning temperature is 290 ° C. (the melt viscosity of the former is 1500 poise, the melt viscosity of the latter is 100 poise) from the spinneret (discharge hole 24) having the discharge holes of
It was extruded at a rate of 1450 m / min at a rate of g / min (composite weight ratio 1/1), drawn at a rate of 3.2 times, and obtained as a side-by-side type composite fiber (100 denier / 24 filaments). The results are summarized in Table 4.

[0030]

[Table 2]

[Comparative Examples 5 to 8] In Example 1, FIG.
Example 3 was carried out in the same manner as in Example 1 except that a spinneret (ejection hole 24) having an ejection hole having the shape shown in Table 3 and having the dimensions shown in Table 3 was used. The results are summarized in Table 4.

[0032]

[Table 3]

[0033]

[Table 4]

[0034]

According to the production method of the present invention, even when two polymers having a large difference in melt viscosity are melted and discharged while being joined eccentrically, the occurrence of kneeling is remarkably suppressed, so that there is no unevenness in fineness. For example, an eccentric conjugate fiber having latent crimpability can be produced extremely stably.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a discharge hole of a spinneret used in the present invention whose cross-sectional area continuously increases.

FIG. 2 is a schematic view of a discharge hole of a conventionally used spinneret.

[Explanation of symbols]

1,1 'polymer inlet portion 2 Polymer - at the end point of introduction, point 2 is the cross-sectional area starts expanding' polymer - point L _A1 to the introductory part of the end point 3 and 3 'the discharge hole is opened in the spinneret surface , L _A2 2,2 ′ hole diameters L _B1 , L _{B2 respectively} 3, 3 ′ hole diameters L _C1 , L _C2 2-3, 2′-3 ′ distance θ taper angle

Claims (4)

[Claims] 1. A melt viscosity difference at a melt spinning temperature is 50.
When melt-spinning an eccentric conjugate fiber in which two kinds of polymers each having 0 to 4000 poise are joined, the eccentric composite fiber has a discharge hole having a shape in which a discharge cross-sectional area continuously increases, and the discharge hole has the following (1) to A method for melt-spinning eccentric conjugate fibers, comprising using a spinneret satisfying (3) at the same time. (1) Cross-sectional area S at point A where the cross-sectional area of the discharge hole starts to expand
_A is 0.0314~0.7850mm ^{2 (2)} discharge Anadan area cross-sectional area S _B of the point B to the maximum 3.142Mm ² or more (3) the angle θ is 10 to the discharge hole is enlarged continuously 45 ゜ 2. The method according to claim 1, wherein the eccentric conjugate fiber is a side-by-side type conjugate fiber. 3. The method according to claim 1, wherein the two kinds of polymers having a difference in melt viscosity are both polyester. 4. The two polymers having a difference in melt viscosity,
3. The method for melt spinning eccentric conjugate fibers according to claim 1, wherein the eccentric composite fibers are the same kind of polyester having different intrinsic viscosities.