JP2001226817A - Spinneret pack for monofilament - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spinneret pack capable of manufacturing a core-sheath type monofilament for screen gauze having <=18 dtex from a single kind of polymer at a low cost aiming the prevention of shaving of the monofilament during textile processing. SOLUTION: A spinneret pack for the melt spinning of a monofilament by introducing a single kind of thermoplastic polymer. In the spinneret pack, two kinds of flow passes are formed to brunch the introduced polymer. One flow pass has a shape of passage which can shorten the retention time of the polymer in order to suppress the depolymerization of the polymer (Pc) and consists of an introducing hole (H1) for passing the polymer (Pc) to form the central part of the monofilament, and the other flow pass has a shape of passage where the retention time of a polymer (Ps) is longer so that the depolymerization of the polymer (Ps) is accelerated, and which surrounds the outer periphery of the polymer forming the central part of the monofilament, at the same time. In the spinneret pack for monofilament, a group of the upper introducing holes (H2), slots (G) and a group of the lower introducing holes (H3) are further formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spinneret pack for producing a monofilament having a core-sheath structure in a cross section of a fiber. More specifically,
In the bridge plate part which is a constituent member of the spinneret pack, a difference in the residence time of the polymer is provided between the center part and the outer peripheral part of the bridge plate. A difference in the intrinsic viscosity is generated at the center of the bridge plate, and a polymer with a high intrinsic viscosity at the center of the bridge plate and a low intrinsic viscosity at the outer periphery is supplied to the spinneret. As a result, the core has a high intrinsic viscosity and the sheath has a low intrinsic viscosity The present invention relates to a spinneret pack for a monofilament for obtaining a monofilament having a core-sheath structure having a viscosity of 18 dtex or less.

[0002]

2. Description of the Related Art Conventionally, in a monofilament for a high mesh and screen gauze which requires a high strength and a high modulus of fineness of 18 dtex or less, generally, in order to obtain a high strength and a high modulus, a monofilament manufacturing process is required.
It is common practice to provide high-magnification stretching to increase the orientation and crystallization of the monofilament. However, in the screen gauze manufacturing process, high-density woven fabrics are processed at a high speed, so the monofilaments are repeatedly subjected to strong friction with the woven machine parts. Is more likely to occur. Therefore, it is extremely important to make the surface of the monofilament difficult to be scraped.

[0003] In particular, this tendency becomes remarkable in monofilaments having a high fiber orientation and crystallization and a small fineness.
During weaving, weaving is frequently interrupted, which affects work efficiency and fabric quality. For this reason, in order to prevent the surface of the monofilament from being scraped, it is considered that the orientation or crystallization of the surface layer portion (sheath portion) of the monofilament is reduced and the orientation or crystallization of the central portion (core portion) is increased. I have.

For example, Japanese Patent Application Laid-Open No. 62-276048 proposes a monofilament having a core-sheath structure in which a polyester is used as a core, and a hard-to-cut polymer such as nylon is used as a sheath. However, in this conventional technique, a monofilament is manufactured by using two types of polymers, and a melting device is required for each polymer as a manufacturing facility.

In addition, regarding the structure of a spin block or a spinneret pack which is a spinning equipment, since core-sheath type composite fibers are produced using two kinds of polymers, the distribution channels of the respective polymers become complicated and large-scale. However, there is a problem that equipment cost and polymer cost are increased.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to
For a monofilament of dtex or less, the intrinsic viscosity difference of the polymer is generated in the spinneret pack using only one kind of polymer without using two kinds of polymers, and the fiber surface is hardly shaved in a fabric processing step. An object of the present invention is to provide a spinneret pack for a monofilament for obtaining a monofilament having a core-sheath structure at low cost.

[0007]

Means for Solving the Problems The present inventors have proposed 18 dt.
ex or less than monofilaments at the time of fabric processing, without using two types of polymers as in the prior art,
In order to develop a method for obtaining a monofilament having a core-sheath structure at low cost using a single kind of polymer, intensive studies have been made. As a result, it has been found that a monofilament having a core-sheath structure can be obtained by positively giving a difference in residence time to the polymer in the spinneret pack, and the present invention has been accomplished based on this finding.

That is, the spinneret pack of the present invention comprises:
"A spinneret pack for introducing a single type of thermoplastic polymer and melt-spinning as a monofilament,
The spinneret pack is formed with two kinds of flow paths for diverting the introduced polymer, and one of the flow paths has a polymer residence time in order to suppress depolymerization of the polymer. A flow path for passing a polymer having a shortened flow path shape and forming a central portion of the monofilament, and the other type of flow path has a residence time of the polymer such that depolymerization of the polymer is promoted. Has a long flow path shape, and is a flow path for surrounding the outer peripheral portion of the polymer forming the central portion of the monofilament.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The polymer used in the present invention is not particularly limited.
It is assumed that a single type of polymer that can be suitably used for screen gauze applications is used. Therefore, to obtain this high mesh screen gauze,
A polymer that can obtain high strength and high modulus is preferable,
Examples of such a polymer include polyethylene terephthalate. In particular, in such applications, since a strength of 5 gf / dtex or more is required, polymers having these physical properties include, among others, a high intrinsic viscosity having an intrinsic viscosity (IV) of 0.6 to 0.9. It is desirable to use low-area polyethylene terephthalate.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic front sectional view schematically illustrating a spinneret pack for monofilament (indicated by reference numeral 1) used in the present invention.
The spinneret pack is substantially loaded with a single type of thermoplastic polymer. In addition, the spinneret pack 1 is shown in FIG.
As shown by the hatched portion therein, the spinning component includes a filtering member 2, a bridge plate 3, a spinneret 4, and the like.

Here, as the filtering member 2, for example, glass beads, metal sand, wire mesh filter, non-woven metal filter, porous sintered metal filter, etc. can be exemplified. Usually, a combination of two or more of them can be used as a filter medium including a filter layer. The filtering member 2 is usually provided on the upstream side of the spinneret pack 1 with respect to the polymer supplied into the spinneret pack 1. Then, here, it plays a role of removing foreign substances or of trickling the polymer to uniformly heat the polymer. Furthermore, by providing a filler layer such as glass beads or metal sand in this part, the volume occupied by the polymer in this part is reduced, and the residence time of the polymer is shortened. Also plays a role of preventing thermal degradation due to stagnation for a long time.

Next, since the detailed structure of the bridge plate 3 will be described later, only its function will be briefly described here. In other words, the function of the bridge plate 3 is that even if the filtration pressure required for passing the polymer through the filtration member 2 increases, the filtration member 2 itself is deformed or damaged by the increased filtration pressure. It plays a role as a strength member that supports it so as not to be damaged. Further, together with such a function, it also functions as a distribution plate for distributing the polymer that has passed through the filtering member 2 to the spinneret 4.

Then, the polymer supplied from the bridge plate 3 is finally spun from a polymer discharge hole formed in a spinneret 4 provided at the most downstream side to form a monofilament.

In the spinneret pack 1 of the present invention configured as in the above embodiment, one of the major features of the present invention is that "in the spinneret pack 1, a single kind of polymer introduced is introduced. The following two types of flow paths for diverting are formed. "

In other words, one of the two types of flow path is defined as a flow path shape in which the residence time of the polymer is shortened in order to suppress the depolymerization of the polymer, and the central portion of the monofilament is formed. It is referred to as a "flow channel for passing the polymer to be formed." By doing so, the core portion (center portion) of the monofilament that maintains its initial properties without depolymerization (thermal degradation) can be formed.

The other type of flow path includes a flow path having a long residence time of the polymer so as to promote the depolymerization of the polymer, and an outer peripheral portion of the polymer forming the central portion of the monofilament. Channel to surround "
And In this manner, the core of the monofilament is depolymerized (thermally degraded) by staying for a long time and receiving excessive heat to form a sheath having a reduced degree of polymerization. A sheath portion is formed by surrounding the portion (center portion).

Therefore, the monofilament thus spun has a core-sheath type fiber structure when viewed in a cross section of the fiber, and the orientation of the sheath part (surface layer part) of the core-sheath type monofilament is determined. Crystallization can be kept low. On the other hand, conversely, the orientation and crystallization at the core (center) can be increased because a high degree of polymerization (high intrinsic viscosity) is maintained without being depolymerized. For this reason, it is possible to prevent the surface of the monofilament from being cut off in the weaving process by the operation described in the section of the related art.

On the other hand, in the conventional spinneret pack, how to devise the polymer so that the polymer does not stay for a long time and is not thermally degraded is a design standard of an excellent spinneret pack. The focus was on designing the pack. If the polymer stays in some part of the spinneret pack for a long time and causes thermal deterioration, the thermally deteriorated polymer is mixed into the product and the quality of the obtained fiber is reduced. Is significantly impaired.

For example, as a bridge plate designed based on such a concept, there can be mentioned a conventional bridge plate schematically illustrated in FIG. 3A is a schematic plan view, and FIG. 3B is a schematic front sectional view.

In the conventional bridge plate 3 'illustrated in FIG. 3, the introduction holes H' for uniformly supplying the polymer to the spinneret 4 illustrated in FIG. 1 are distributed substantially uniformly over the entire surface. Are perforated. Therefore, the polymer is supplied to the spinneret 4 from these introduction holes H 'almost uniformly as shown by the arrows in the figure, and as a result, fibers of uniform quality can be obtained.

On the other hand, the spinneret pack 1 of the present invention
2 will be described in detail below with reference to FIG. 2 taking the embodiment of the bridge plate 3 illustrated in FIG. 2 as an example. 2A is a schematic plan view schematically illustrating the shape of the bridge plate 3 as viewed from the upstream side of the polymer flow, and FIG. 2B is a front sectional view thereof.

In the bridge plate 3, which is one embodiment of the present invention, as shown in FIG. 2, a single kind of polymer introduced into the spinneret pack 1 is used as a polymer Pc and a polymer Ps, respectively. Two types of flow paths for diverting are formed.

That is, as one of the flow paths, the introduction hole H1 is a flow path through which the polymer Pc for forming a monofilament core in the center of the bridge plate 3 flows down.
Are drilled. As the other flow path, on the outer peripheral side of the bridge plate 3, a flow path for flowing down the polymer Ps for forming the sheath portion of the monofilament is referred to as “the upper introduction hole H2 group, the retention groove G, and the lower part. An introduction hole H3 group "is formed.

At this time, the residence time of the polymer Ps in the flow path is longer than that of the polymer Pc.
Factors such as the length of each channel, the amount of polymer retained in the channel, or the flow rate of the polymer in the channel are determined.
The criterion for selecting this factor is that the polymer can maintain a high intrinsic viscosity without depolymerization in the flow path where the polymer Pc flows, while the flow path where the polymer Ps flows has a shape that promotes depolymerization. Is the criterion.

However, the flow rate ratio of the polymer Pc and the polymer Ps is sufficient if it plays a role as a protective layer for preventing scraping of the monofilament during weaving as the flow rate of the polymer Ps. It is necessary to set the thickness so as to be able to form the surface layer thickness that can be achieved.

In order to satisfy the above-described conditions, in the bridge plate 3 of FIG. 2 exemplifying one embodiment of the present invention, on the other hand, as a flow path for flowing the polymer Pc to the center of the bridge plate. An introduction hole H1 is formed.

On the other hand, as the flow path for flowing the polymer Ps, the "upper inlet hole H2 group, the retaining groove G, and the lower inlet hole H3 group" are formed as described above. At this time,
A plurality (24 in the figure) of upper introduction holes H2 and lower introduction holes H3 are each formed obliquely toward the outer peripheral side wall from positions near the outer peripheral side of both the front and back surfaces of the bridge plate 3. As described above, the reason why the upper introduction hole H2 group and the lower introduction hole H3 group are obliquely drilled toward the outer peripheral side wall is to adjust the angle at the time of drilling.
This is because the respective hole lengths of the upper introduction hole H2 group and the upper introduction hole H2 group can be freely set to predetermined values.

The upper introduction hole H2 and the lower introduction hole H3
The reason why many holes are formed is that a sufficiently large heat receiving area for the polymer Ps can be taken. Furthermore, the cross-sectional shape of these holes does not need to be limited to a round shape,
For example, any shape such as an elliptical shape, an elliptical shape, a slit shape, a triangular shape, and a quadrangular shape can be adopted, but a round shape is preferable in consideration of processing cost, ease of processing, and the like.

At this time, the necessary conditions such as the hole diameter, the hole length, the number of holes, and the like of each of the upper introduction hole H2 and the lower introduction hole H3 group are such that the polymer Ps is led to the outer peripheral portion of the bridge plate 3, where Depolymerization to an appropriate degree (thermal degradation)
As described above, it is possible to secure a sufficient residence time to allow the polymer Ps to proceed, thereby setting the conditions to reduce the intrinsic viscosity of the polymer Ps.

Further, as the bridge plate 3 of the present invention, the more important point is that the polymer Ps
The groove G which plays a role as a staying chamber for adjusting the staying time of the tire is circumferentially engraved along the outer peripheral surface thereof. Thereby, the polymer Ps is introduced from the upper introduction hole H2 group into the groove G, which is the retention chamber, and the required residence time is adjusted and secured, and then distributed from the groove G to the lower introduction hole H3 group. You.

In the embodiment described above, the polymer flow path is divided into two types, and when the polymer is divided into the respective flow paths, the bridge plate 3 is used to make these flow paths into the bridge plate 3. Was formed. However, in the present invention, it is not necessary to limit to such an embodiment. For example, such a flow path may be provided in the filter member 2, the spinneret 4, the pack body, and the like.

[0032]

Next, the present invention will be described in more detail by way of examples. A bridge plate having the shape shown in FIG. 2 was mounted on a known spinneret pack as shown in FIG. At this time, the thickness of the bridge plate 3 is 15
A disk-shaped material having a diameter of 35 mm and a diameter of 35 mm was used. Further, a groove G having a width of 10 mm and a depth of 1 mm was formed at the center of the outer peripheral surface of the outer peripheral side wall along the circumferential direction as a polymer retention chamber. Further, at this time, an introduction hole H1 for a polymer Pc having an upper hole diameter of 6 mm and a lower hole diameter of 3 mm was formed in the center of the bridge plate 3.

Further, from the surface of the bridge plate 3 toward the outer peripheral side wall, 24 groups of upper introduction holes H2 having a pitch diameter of φ33 mm are arranged on the concentric circles having a pitch diameter of φ33 mm and the diameter of the hole is φ1 mm. 4 for surface
Twenty-four were pierced at a piercing angle of 0 °. At this time, similarly, the pitch circle diameter of the lower introduction hole H3 group is φ2.
24 equidistantly arranged on a concentric circle of 4 mm and a hole diameter of 1 m
m lower introduction holes H3 were drilled at 24 holes at a drilling angle of 35.5 ° with respect to the back surface.

Then, polyethylene terephthalate made of a single polymer having an IV of 0.87 was introduced into a spinneret pack equipped with the bridge plate 3 according to a conventional method, and a discharge hole having a diameter of 0.32 mm was formed. Spinning temperature 302 ° C, winding speed 1180m from spinneret
/ Min.

Further, about one day after spinning the obtained undrawn monofilament, the rotation speed is 800 m / m.
in, a heating temperature of 100 ° C., a roller heater, and a heating temperature of 195 ° C. and 140 ° C., respectively.
2gf / dtex, elongation at break 30.4%, fineness 10
A dtex monofilament was obtained. The obtained monofilament was divided into a core portion and a sheath portion in the yarn length direction, and the intrinsic viscosity was measured at each portion according to a standard method. as a result,
The intrinsic viscosity difference between the sheath and the core was 0.08.

On the other hand, a monofilament was manufactured under the same conditions as above except that the conventional bridge plate 3 'shown in FIG.
A 0dtex monofilament was obtained. Here, a disk-shaped bridge plate having a thickness of 15 mm and a diameter of 35 mm was used as the bridge plate 3 ′ in FIG. At this time, 45 polymer introduction holes having a diameter of 1 mm were perforated in the bridge plate 3 'so as to be distributed almost uniformly over the entire surface. When the monofilament obtained at this time was evaluated, the difference in intrinsic viscosity between the sheath and the core was hardly observed and was 0.01 or less.

[0037]

As described above, according to the spinneret pack of the present invention, a core-sheath type monofilament of 18 dtex or less having a distinctive intrinsic viscosity difference between a sheath portion and a core portion is melted from a single polymer. Can be spun. Also,
The intrinsic viscosity, which evaluates the degree of depolymerization (thermal degradation), can also give a distinctly large difference, whereby the orientation and crystallization in the sheath of the monofilament can be suppressed, and the surface during weaving can be reduced. This has a remarkable effect that the shaving of the steel can be improved.

Further, the spinneret pack of the present invention can easily obtain a core-sheath type monofilament with a single kind of polymer, and can be used with a conventional spinneret pack producing a core-sheath type monofilament using two kinds of polymers. By comparison, the increase in equipment cost and polymer cost, which were problems in the prior art, was eliminated, thereby enabling a spinning equipment capable of obtaining a monofilament having a core-sheath structure at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic front sectional view schematically illustrating a spinneret pack for a monofilament.

FIG. 2 is a schematic view schematically illustrating one embodiment of a bridge plate of the present invention, wherein FIG. 2 (a) is a plan view and FIG. 2 (b) is a front sectional view thereof.

3A and 3B are schematic views schematically illustrating a conventional bridge plate, in which FIG. 3A is a plan view and FIG. 3B is a front sectional view thereof.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 spinneret pack 2 filter member 3 bridge plate 4 spinneret G retention groove H1 introduction hole (for polymer Pc) H2 upper introduction hole (for polymer Ps) H3 lower introduction hole (for polymer Ps) Pc Monomer filament forming polymer Ps Monofilament sheath-forming polymer

Claims (4)

[Claims] 1. A spinneret pack for introducing a single type of thermoplastic polymer and melt-spinning it as a monofilament, wherein the spinneret pack has two types of diverging parts for introducing the introduced polymer. A channel is formed, in which case one type of channel has a channel shape that shortens the polymer residence time in order to suppress depolymerization of the polymer, and passes the polymer that forms the central part of the monofilament. The other type of flow path has a flow path shape having a long residence time of the polymer so that the depolymerization of the polymer is promoted, and an outer peripheral part of the polymer forming the central part of the monofilament. A spinneret pack for a monofilament, characterized in that it is a flow path for surrounding the spinneret. 2. The spinneret pack for a monofilament according to claim 1, wherein a retention chamber for the polymer is provided in the middle of the flow path for promoting the depolymerization of the polymer. 3. The spinneret pack for monofilaments according to claim 1, wherein the two flow paths according to claim 1 are formed in a bridge plate incorporated in the spinneret pack. 4. The spinneret pack for a monofilament according to claim 1, wherein a monofilament for a high mesh screen having a fineness of 18 dtex or less is spun.