JPH04202806A - Method and spinneret for preparing sheath-core conjugate fiber - Google Patents

Abstract

PURPOSE:To prepare the subject conjugate fiber having a high strength and free from the ununiform thickness and eccentricity of a sheath component by joining plural melted polymer flows into a sheath-core type flow, and subsequently melt-spinning the melted polymer flow through a conical passageway tapered from the inlet toward the spinning opening. CONSTITUTION:When two or more kinds of melted polymer flows are joined into a sheath-core type flow to prepare a sheath-core type conjugate fiber, polyethylene terephthalate, etc., as a core polymer A and polyethylene, etc., as a sheath polymer B are melted, joined to each other through the distribution plates 1,2 of a spinneret, and melt-spun through a spinneret 3 having a conical counter bore 4 tapered from the inlet toward the spinning opening 6 or a place near the spinning opening 6 to provide the objective sheath-core type conjugate fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a core-sheath composite fiber, and a cap plate and a cap device used therein. For details,
The present invention relates to the production of core-sheath type composite fibers in which the thickness of the sheath portion is uniform, and in particular, in the case of concentric circular type composite fibers, there is no eccentricity.

[Prior art] In recent years, many core-sheath type composite fibers in which two or more types of polymers are arranged in a core-sheath type have been developed and manufactured. It has various excellent properties that other manufactured fibers do not have. For example, when using a core-sheath type composite fiber with high melting point polypropylene or polyethylene terephthalate as the main component and low melting point polyethylene as the sheath component, the low melting point polyethylene on the sheath side (outside) easily heats the fibers together. Since it can be fused and the strength of the high melting point polypropylene or polyethylene terephthalate core steel is high, a high strength nonwoven fabric can be easily produced by a heat fusion method.

Regarding the manufacturing technology of core-sheath type conjugate fibers, we will explain it by taking as an example a concentric core-sheath type conjugate fiber with a main component made of polymer A and a sheath component made of polymer B.
It is manufactured by melt spinning using a spinneret as shown in the figure. There, two types of molten polymer streams A and B that passed through the distribution plate 1 are made into concentric circles by the distribution plate 2,
While maintaining a concentric circular shape, the yarn passes through a cylindrical counterbore 4 having the same inner diameter from the inlet provided in the spinneret plate 3 to the front surface of the throttle part 5, is narrowed in the throttle part 5, and is spun out from the spinneret 6. Core-sheath type composite fibers are manufactured.

By the way, in core-sheath type composite fibers, differences in melt viscosity between multiple polymers, pressure balance of each polymer flow at the point where the polymer flows merge, etc. may cause uneven thickness of the sheath portion, eccentricity, It is known that this has a large effect on the variation in denier between single fibers, but the conventional method shown in Fig. 1 has a cylindrical structure in which the inner diameter of the counterbore is equal from the entrance to the front of the constriction part. When using the cap device, the thickness of the closed side component tends to be uneven, and concentric composite fibers have the disadvantage of causing eccentricity.

Thickness unevenness and eccentricity of the closed side component in core-sheath type composite fibers tend to cause damage, peeling, and falling off of the closed side component, and exposure of the outer side component. often exhibits no characteristics. Furthermore, uneven thickness and eccentricity of the closed-side component can cause contamination of equipment such as heaters and rollers due to falling of the closed-side component, and various other troubles during various manufacturing and processing processes from the spinning process to the final product. This easily occurs and causes serious process passability problems.

[Problems to be Solved by the Invention] The object of the present invention is to provide a core that is free from the above-mentioned drawbacks in core-sheath type composite fibers, has no uneven thickness of the closed side component, and has no eccentricity in concentric type composite fibers. An object of the present invention is to provide a method and an apparatus that can stably produce sheath-type composite fibers.

[Means for Solving the Problems] As a result of continuous research by the present inventors to achieve the above object, in a die device for manufacturing core-sheath type composite fibers, the inner diameter of the counterbore of the die plate is It has been found that the above objective can be achieved by melt spinning a core-sheath type composite fiber in a conical shape that gradually becomes thinner from the inlet to the constriction part or the spinneret, instead of being uniform from the constriction part or inlet to the spinneret. I found it.

Therefore, the present invention provides a method for producing a core-sheath type composite fiber in which two or more types of molten polymer streams are merged into a core-sheath type and melt-spun, in which the merged molten polymer streams are passed from an inlet to a spinneret or a vicinity of the spinneret. This is a method for producing core-sheath type composite fibers, which is characterized by performing melt spinning through a conical passage that becomes narrower towards the end.

Furthermore, the present invention provides a spindle plate for producing a core-sheath type composite fiber having a conical counterbore that tapers from an inlet toward a spinneret or the vicinity of the spinneret, and a core-sheath type composite fiber comprising the spinneret plate. Includes a die device for manufacturing composite fibers.

In the present invention, the location where the conical passage is provided (
Although the end point of the conical passage is ``toward the spinneret or the vicinity of the spinneret'', this means that even if the end point of the conical passage is the spinneret (discharge port) of the spinneret plate, it is slightly upstream of the spinneret. This means that it may be at the front surface on the upstream side of a so-called constriction section provided on the side, or it may be further upstream to some extent.

Further, the term "pyramidal" in the present invention typically refers to a conical shape, but also includes a pyramidal shape, such as a triangular pyramidal shape, a quadrangular pyramidal shape, a polygonal pyramidal shape or more than a pentagonal pyramidal shape. Generally, a conical shape is desirable.

The present invention will be compared with the conventional technology by taking as an example the manufacture of a single-core type core-sheath type composite fiber in which a single core consisting of a side component A is surrounded by a closed side component B concentrically. Figure 1~
This will be explained in detail with reference to FIG.

When manufacturing a single-core type core-sheath type composite fiber, the distribution plate 2
The seed molten polymers A and B meet to form a core-sheath type molten polymer flow, but in this case, it is necessary to keep the pressure difference between the two within an appropriate range, and the If the pressure difference is large, the molten polymer on the high pressure side will flow back into the polymer flow path on the low pressure side, and a normal core-sheath structure will not be formed. Molten polymer stream AIl!
: B forms a core-sheath polymer flow on the counterbore 4 of the spinneret plate 3 while maintaining an appropriate pressure balance, passes through the counterbore 4 in a laminar flow state, and reaches the spinning nozzle 6, but the distribution The laminar flow state in the counterbore 4 may be affected by a slight deviation during assembly between the plate 2 and the cap plate 3, a slight deviation in the injection direction of the master side polymer A into the sheath side polymer B on the distribution plate 2, etc. It is difficult to maintain a core-sheath type polymer flow in a concentric state at all times.

Then, the inner diameter mQ of the entrance of the counterbore 4 is
Front inner diameter n. In the conventional spinneret device for producing core-sheath composite fibers shown in FIG. 1, which has the relationship m o = n Q, which is equal to An eccentric core-sheath composite fiber is spun as it is.

In contrast, in the present invention, as shown in FIG. 2, for example, the counterbore 4 has a conical shape that gradually becomes narrower from its entrance to the front surface of the throttle part, and the inner diameter m1 of the entrance of the counterbore 4 and the throttle part 5. The inner diameter n1 of the front surface is m, >
n, the eccentricity of the core-sheath type polymer flow is corrected so that the core is located in the center, and the fibers spun from the spinneret are The result is a good core-sheath type composite fiber with no thickness unevenness or eccentricity.

Moreover, in the present invention, the aperture part 5 in FIG. 2 is omitted,
As shown in Fig. 3, a conical passage may be formed gradually from the entrance of the counterbore to the spinneret 6, and in this case also, the net side component B has good thickness without unevenness and eccentricity. It is possible to produce core-sheath type composite fibers. This third
In the case of the figure, the inner diameter m2 of the entrance of the counterbore 4 and the inner diameter n2 of the spinneret 6 have a relationship such that m2>n.

Furthermore, the shape of the conical passage (counterbore) may be as shown in FIG. 4, in which case m , > n s
The relationship is

In the above, the ratio of the inner diameter of the entrance to the inner diameter of the conical passage,
That is, ml:n, m2:n2 and m3・n3 are
It can be determined depending on various requirements such as the type and viscosity of the polymer used, the number and arrangement of cores in the core-sheath composite fiber, and the cross-sectional shape and thinness of the fiber, but it is usually about 4.1 ~
It is best to set it to approximately 1.51. Further, the distances 11, I2, and 13 from the entrance to the end point of the counterbore (conical passage) are determined according to the various requirements described above, but are usually adopted in the production of core-sheath type composite fibers. It is preferable to set the distance (approximately 20 to 30 mm). Further, the degrees of inclination θ1 and θ2 of the conical passage are determined by the following equations: inner diameter ml, m2, m3 of the inlet of the counterbore: inner diameter n of the end point of the conical passage.
l s n 2, n, and the above distance 11.12,!
It is determined by the value of , but it is usually good to set it to 806 to 90 degrees.

In the present invention, the cross-sectional shape of the core-sheath type composite fiber may be either circular or non-circular (irregular shape).

Examples of the irregularly shaped fibers include triangular, square, pentagonal, hexagonal, etc., and these irregularly shaped fibers can be produced by making the shape of the spinneret into a corresponding irregular shape.

Further, the shape of the core needle in the core-sheath composite fiber does not necessarily have to be circular, and may have an irregular shape as described above.

Further, according to the present invention, not only single-core type core-sheath type conjugate fibers but also multi-core-sheath type conjugate fibers can be manufactured.

Further, the spindle device of the present invention can be any spinneret device for producing core-sheath type composite fibers, which is equipped with a spindle plate having a conical counterbore that becomes thinner from the inlet toward the spinneret or the vicinity of the spinneret. However, other parts (for example, the shape and number of distribution plates, etc.) do not matter.

The types of polymers used are not limited to two types, and even if three or more types are used, a good core-sheath type composite fiber can be produced. There are no restrictions on the combination of polymers as long as they are thermoplastic polymers, and the melt viscosity and flow rate per unit area of the spinneret during spinning are as follows:
A good core-sheath structure can be obtained with any combination within the suitable range for spinning (for example, the suitable range described in Japanese Patent Publication No. 41-293). In addition, in the case of the present invention, even if the melt viscosity and flow rate per unit area of the cap of one of the polymer and the sheath polymer are out of the appropriate range, the melt viscosity of the other polymer and the unit area of the cap If the permeation flow rate is within the appropriate range, a good core-sheath structure can often be obtained. Therefore, in the case of the present invention, a polymer whose melt viscosity and flow rate per unit area of the spinneret are not within the appropriate range for melt spinning, and which could not be conventionally melt spun by itself, can be used with other polymers that can be melt spun. In combination with coalescence, it is possible to perform core-sheath type composite spinning, thereby making it possible to produce fibers with properties not previously available. An example of this is the production of core-sheath type composite fibers in which polyester is used as a core component and ethylene-vinyl alcohol copolymer is used as a closed-side component. It has properties not found in conventional melt-spun fibers, such as color development, water absorption, and drape properties, which are the physical properties of alcohol copolymers.

Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

Example 1 and Comparative Example 1 Polyethylene terephthalate (
Melt viscosity 1100 poise, 290°C), sheath side polymer (
B) polyethylene (melt viscosity 790 poise, 29
0°C), the cap device shown in Fig. 1 (me=n
o= 3 ff1l: mo/no= 11lo=
25111), Polymer A and Polymer B were supplied in the weight ratio shown in Table 1 below, and 21 g/m1n-12 (total of Polymers A and B) was produced from a circular spinneret with an inner diameter of 0.3H. A core-sheath type composite fiber having a circular cross section was produced by spinning it at a ratio of 1,000 m/1 inch and measuring its eccentricity (comparative example).

The cap device shown in FIG. 2 (m, = 3 m+n; n
+=1.5in+; m,/n+=2.0
; l+= 25mm; spinneret inner diameter -〇, 3mm
) A core-sheath type conjugate fiber was produced in the same manner as above (Example), except that the following was used.

The above results are shown in Table 1 below.

In addition, in the above, the eccentricity is expressed as h-a/, where the dimension of the thinnest part of the sheath is a (mid) and the dimension of the thickest part of the sheath is b (m), as shown in Figure 5. It was determined by b. Therefore, the closer h is to 1, the less eccentricity there is.

[Table 1] 0.667 1 1.5 2 2.5 Comparative example (
mo/no=1.0) 0.69 0,66
0.52 0.45 0.42” Example (rr
b/n+=2.0) 0.83 0,90
0.85 0.80 0.77 From the results in Table 1 above, in the case of the example of the present invention in which core-sheath type composite fibers are manufactured using a die device having a counterbore tapered into a conical shape, , Even if the supply amounts of polymer A and polymer B are changed, the degree of eccentricity is close to 1 < (h = 0.77 to 0.90),
While a core-sheath type composite fiber with a uniform sheath thickness and a low degree of eccentricity has been obtained, it is possible to obtain a core-sheath type composite fiber with a uniform sheath thickness and a low degree of eccentricity. In the case of the comparative example corresponding to the conventional technology, the degree of eccentricity was far from 1 (h = 0.69 to 0.42), and the thickness of the sheath was uneven and the degree of eccentricity was large. It can be seen that the fiber becomes a core-sheath type composite fiber, and that this tendency increases as the supply ratio of the core polymer A increases.

Example 2 and Comparative Example 2 Polybutylene terephthalate (
Melt viscosity 1250 poise, 2oooC), sheath side polymer (
B) polyethylene (melt viscosity 1000 boids, 2
00°C), the cap device shown in Fig. 1 (mo=
no=4mm; mo/no=1.0; 1
6 = 301), Polymer A and Polymer B were supplied at the weight ratio shown in Table 1 below, and 25g/l11n·■2 (of Polymers A and B) was fed from a circular spinneret with an inner diameter of 0.3ml1. A core-sheath type composite fiber having a circular cross section was produced by spinning at a ratio of 800 m/win and measuring its eccentricity (Comparative Example 2).

The cap device f shown in FIG. 2 (m 1 = 4 in+;
nl=1.5cm; m,/n+=3. O; I
Core-sheath type composite fibers were produced in the same manner as above, except that the spinneret inner diameter = 0.3 m1) was used.
Example 2).

The eccentricity of the core-sheath type composite fibers produced in Example 2 and Comparative Example 2 was measured in the same manner as in Example 1 and Comparative Example 1.

The results are shown in Table 2 below.

[Table 2] 0.77 1 1.43 Comparative example (m1
/n+=3. ．． 0) 0.50 0.3
7 0.312) Example (m1/n+=3
．． 0) 0.83 0.77
0.72 From the results in Table 2 above, in the case of the example of the present invention in which core-sheath type composite fibers are manufactured using a die device having a counterbore tapered into a conical shape, polymer A and Even if the supply amount with coalescence B was changed, a core-sheath type composite fiber with a uniform sheath thickness and a low degree of eccentricity was obtained. In the case of a comparative example corresponding to the conventional technology that uses a uniform cap device all the way to the front, the eccentricity distance is significantly different from 1 (
h = 0.31 to 0.50), the core-sheath type composite fiber has a non-uniform sheath thickness and a high degree of eccentricity, and this tendency increases as the supply ratio of core polymer A increases. I understand that.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional die device for manufacturing core-sheath type composite fibers. FIGS. 2 to 4 are diagrams showing specific examples of the die device of the present invention for manufacturing core-sheath type composite fibers. FIG. 5 is a diagram showing a measuring method when measuring eccentricity in a core-sheath type composite fiber.

Claims (1)

[Scope of Claims] 1) In a method for producing a core-sheath type composite fiber in which two or more types of molten polymer flows are combined into a core-sheath type and melt-spun, the combined molten polymer flows are passed from an inlet to a spinneret or to a spinning spun. A method for producing a core-sheath type composite fiber characterized by melt spinning through a conical passageway that becomes narrower toward the mouth. 2) A spinneret plate for producing core-sheath type composite fibers, characterized by having a conical counterbore that becomes thinner from the inlet toward the spinneret or the vicinity of the spinneret. 3) A die device for producing core-sheath type composite fibers, comprising the die plate according to claim 2.