JPH0625906A - Spinneret - Google Patents

Abstract

(57) [Abstract] [Objective] During melt spinning of polyethylene terephthalate fiber, it stabilizes the spinning production process by suppressing the generation and accumulation of dirt around the discharge hole of the spinneret, which is an obstructive factor in the manufacturing process. At the same time, the cross-sectional shape and thickness of the thread are kept uniform,
It is a spinneret that can provide polyethylene terephthalate fibers with stable yarn quality. [Structure] An inflow part where the polymer discharge hole faces the polymer inlet,
It is composed of a throttle portion and a discharge portion facing the polymer outlet, and the inflow portion is continuously reduced in diameter in the discharge direction at an angle of 0.2 to 3 ° with respect to the central axis of the discharge hole. The portion comprises a portion whose diameter is continuously reduced in the discharge direction at an angle of 20 to 50 ° with respect to the central axis of the discharge hole, and the discharge portion has an angle of 3 to 20 ° with respect to the central axis of the discharge hole. The diameter is continuously reduced in the discharge direction up to the outlet of the discharge hole, and the length L of the discharge portion is L.
And the ratio L / D of the diameter D of the discharge hole outlet is 1 to 10,
A spinneret having a diameter D at the outlet of the discharge hole of 0.1 to 0.5 mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spinneret used for melt spinning, more specifically to melt spinning of polyethylene terephthalate fiber, and more specifically to melt spinning of polyethylene terephthalate fiber. Stabilizes the spinning production process by suppressing the generation and accumulation of stains around the discharge hole of the spinneret, which is a factor that hinders the manufacturing process, while maintaining a uniform cross-sectional shape and thickness of the yarn.
The present invention relates to a spinneret having a special discharge hole shape capable of providing polyethylene terephthalate fiber having stable yarn quality.

[0002]

2. Description of the Related Art In the production of polyethylene terephthalate fibers by melt spinning, extruding them into the atmosphere through a spinneret having a large number of small-diameter polymer discharge holes in order to impart a fiber morphology to the molten polymer This is the first step. Therefore, a wide variety of spinnerets have been proposed and used, depending on the desired final product morphology. In addition, ultrafine fibers with a diameter of less than 10 μm, irregularly shaped cross-section fibers with numerous protrusions, high-speed spinning technology with a take-up speed of over 5000 m / min, etc. are adopted.
Even in practical application, what kind of spinneret is used for spinning is a very important technical element. Furthermore, the spinneret plays an important role in maintaining the stability of the yarn manufacturing process.

Usually, in the process for producing polyethylene terephthalate fiber, a spinneret in which the discharge portion 5 of the polymer discharge hole 2 is a cylindrical fine hole as shown in the spinneret sectional view of FIG. 3 is used. When using such a spinneret,
When continuously spinning for a long time, additives, monomers, oligomers, etc. contained in polyethylene terephthalate,
Alternatively, thermal decomposition products or titanium oxide added as a matting agent adheres to the periphery of the polymer discharge holes, and these are complicatedly changed and accumulated under the influence of heat and oxygen in the air. . For this reason, the releasing property of the discharged polymer is deteriorated, the spun yarn is bent, and the spitting, the yarn breakage, etc. are caused, and the spinnability becomes unstable. Therefore, when the amount of dirt accumulated around the polymer discharge hole increases, melt spinning is interrupted,
You must clean the area around the spinneret outlet or replace the spinneret. When cleaning or replacing the spinneret, the production is naturally interrupted, and a lot of labor is required, which greatly affects the manufacturing cost.

In order to suppress the stain around the polymer discharge hole of the spinneret and to improve the wiping-off property of the stain, for example, polyorganosiloxane containing a heat-resistant agent is generally applied to the surface of the spinneret. However, since polyorganosiloxane is thermally denatured with time and stains are accumulated, it is necessary to perform a so-called spinner-correction work to scrape stains around the polymer discharge holes with a spatula-like tool and apply polyorganosiloxane again. is there. As a method of extending the correction cycle of the spinneret, a method of sealing the lower surface of the spinneret with an inert gas such as nitrogen, helium, or steam to suppress the growth of adhered dirt is generally known.
This method requires a large amount of investment because the equipment is large-scale, and the operating cost is high because the inert gas used for sealing is required, and the workability during desorption of the pack and cleaning of the spinneret surface is poor. Further, there is a problem that the management for controlling the physical properties of the spun yarn becomes complicated.

As a method for suppressing the generation and growth of foreign matter deposited due to a part of the discharged polymer contacting and adhering to the peripheral portion of the discharge hole, Japanese Patent Laid-Open No. 63-120109 discloses a method of melt spinning polyester. A spinneret having a tapered hole whose diameter is increased at an angle of 3 to 25 ° with respect to a central axis of a discharge hole of the spinneret has been proposed. The publication discloses that by gradually expanding the discharge hole, the viscous substance extruded from the fine hole reduces the property that the viscous substance tries to spread beyond the diameter of the fine hole due to stress relaxation, that is, the so-called ballast effect, and suppresses the direct adhesion of the polymer. It is in. However, according to the test results of the present inventors, although the reduction of the ballast effect is certainly confirmed by adopting such a shape, the stain on the mouthpiece is not reduced, and further, the polyethylene containing the matting agent and the colorant is not reduced. It has been found that, when melt-spinning terephthalate or polyester having a low intrinsic viscosity, there is a problem that stains tend to be accumulated.

When the inventors of the present invention repeated a number of experiments and observed the occurrence of stains with a magnifying glass while performing melt spinning, minute stains were generated around the polymer discharge hole immediately after the start of spinning, and these minute stains were generated. It was found that sublimates from the polymer adhered to various stains, and the polymer spread due to the ballast effect adhered to the stains to grow. The minute stains generated immediately after the start of spinning were mainly titanium oxide added as a matting agent to polyethylene terephthalate and modified products of antimony compounds as polymerization catalysts. Furthermore, we found that the stain that first adheres to the periphery of the polymer discharge hole can be significantly reduced by making the spinneret shape a special shape, and the growth of stain around the spinneret discharge hole can be dramatically suppressed. It was

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art and to provide a spinneret capable of stabilizing the yarn manufacturing process for a long period of time and reducing the frequency of spinneret surface cleaning operations. To provide.

[0008]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a spinneret having a polymer discharge hole composed of an inflow portion, a throttle portion and a discharge portion, which satisfy the following requirements (A) to (C). To be achieved. (A) The inflow portion is continuously reduced in diameter in the discharge direction at an angle of 0.2 to 3 ° with respect to the central axis of the discharge hole. (B) The diameter of the throttle portion is continuously reduced in the discharge direction at an angle of 20 to 50 ° with respect to the central axis of the discharge hole. (C) The diameter of the discharge portion is continuously reduced to the discharge hole outlet portion in the discharge direction at an angle of 3 to 20 ° with respect to the central axis of the discharge hole, and the length L of the discharge portion and the discharge hole outlet portion are reduced. L / D = 1 to 10 and the diameter D of the discharge hole outlet is 0.1 to 0.5 mm.

Melt-spinning is performed using a conventional spinneret having a discharge port 2 as shown in FIG. 3 which is composed of a polymer introduction part 3, a throttle part 4 and a polymer discharge part 5 having a cylindrical pore. In the manufacturing method, when the molten polymer flows into the discharge of the spinneret, the shear rate rapidly increases, and the flow of the polymer becomes extremely unstable, so that a flow velocity distribution is generated in the polymer. When polyethylene terephthalate contains titanium oxide, the titanium oxide is concentrated on the wall of the spinneret where the polymer flow velocity is slow in the discharge hole of the spinneret. As a result, titanium oxide oozes out from the edge of the outlet of the discharge hole, resulting in minute contamination. The sublimate in the discharged polymer adheres to the minute dirt, or the discharged polymer spread due to the dispersion effect adheres to the minute dirt, so that the dirt rapidly grows. Further, in the conventionally used spinneret, as shown by a polymer drawing section 4 in FIG. 3, a one-step or several-step conical drawing is provided between the polymer inflow section 3 and the polymer discharge section 5. Some are attached. If the discharge portion 5 communicating with the discharge hole outlet is cylindrical or has a large diameter in the discharge direction, the flow of the polymer is extremely unstable. Although the detailed reason is not clear, particles such as additives and foreign matters in the polymer will not be obtained unless the diameter of the discharge portion communicating with the discharge hole outlet portion in the spinneret of the present invention is reduced in the discharge direction and high pressure is applied. It is inevitable that the edge of the outlet of the discharge hole will seep out and become a minute stain. It should be further noted that the polyethylene terephthalate fiber produced by the spinneret of the present invention has a very smooth polymer flow inside the spinneret, so that a fiber with less unevenness in the longitudinal direction can be obtained. .

In the spinneret of the present invention, it is necessary that the discharge portion has a small diameter in the discharge direction at an angle of 3 to 20 ° with respect to the central axis of the discharge hole. Preferably, with respect to the central axis of the discharge hole,
The angle is 6 to 10 °. If the angle of the discharge part is less than 3 °, the polymer will not flow smoothly in the discharge hole,
The flow stabilizing effect of the discharge polymer is small. When the angle of the discharge hole is larger than 20 °, the back pressure of the die becomes low, and the polymer metering property deteriorates. In FIG. 2, the ratio L / D of the length L of the discharge portion of the discharge hole and the diameter D of the discharge hole outlet portion needs to be 1 to 10. The preferred L / D is 2-4. L / D
When the value is less than 1, the pressure in the die hole is large, and the discharge of the polymer becomes unstable. On the other hand, when L / D exceeds 10, the flow resistance of the polymer becomes too large, the back pressure of the spinneret becomes high, and the processing of the spinneret becomes difficult, which is not preferable. In addition, the diameter D of the discharge hole outlet is 0.1 to
It is necessary to use a spinneret that is 0.5 mm. The diameter D of the outlet of the discharge hole is preferably 0.25 to 0.35 mm. When the diameter D of the discharge hole outlet is less than 0.1 mm, it is difficult to accurately process the inner wall of the discharge hole.
It is difficult to obtain a uniform yarn during melt spinning. On the contrary, 0.5 mm
If it exceeds, it is difficult to obtain a polyester fiber free of yarn unevenness.

The inflow part 3 of the polymer discharge hole of the spinneret shown in FIG.
Needs to be continuously reduced in diameter in the discharge direction at an angle of 0.2 to 3 ° with respect to the central axis of the discharge hole. Preferably, the diameter is reduced at an angle of 0.5 to 3 ° in the discharge direction. If the diameter of the inflow portion is continuously reduced in the discharge direction at an angle of less than 0.2 ° with respect to the center axis of the discharge hole, or if the diameter is not reduced in the discharge direction at all, the inflow of the molten polymer is not possible. Easy to be stable. By slightly reducing the diameter in the discharge direction, the flow of the molten polymer becomes extremely smooth. Further, when the diameter of the inflow portion is reduced at an angle larger than 3 ° with respect to the central axis of the discharge hole, the diameter of the inlet of the discharge hole inflow portion becomes too large, and the spinneret is subjected to the pressure applied during melt spinning. The spinneret may not be able to withstand, and the spinneret may be deformed.

The drawing section 4 of the polymer discharge hole of the spinneret shown in FIG.
Needs to be reduced in diameter in the discharge direction at an angle of 20 to 50 ° with respect to the central axis of the discharge hole. Preferably, the diameter is reduced in the discharge direction at an angle of 30 to 40 ° with respect to the central axis of the discharge hole. If the angle of the throttle is larger than 50 ° with respect to the central axis of the discharge hole, the molten polymer tends to stay in the portion where the angle of the wall surface changes, and if it is smaller than 20 °, the flow resistance of the polymer increases, so the back of the die This is not preferable because the pressure becomes high and the diameter of the inflow portion must be reduced. Furthermore, processing of the spinneret becomes difficult. Further, it is preferable that the narrowed portion has two or more stages as shown in FIG. When forming the narrowed portion in two or more stages, it is preferable that the angle with respect to the central axis of the discharge hole is smaller in the polymer discharge direction. For example, the narrowed portion 4A in FIG. 2 is reduced in diameter in the polymer discharge direction at an angle of 35 ° with respect to the center axis of the discharge hole, and subsequently, the narrowed portion 4B is reduced in diameter in the polymer discharge direction at an angle of 25 °. Therefore, the fluidity of the polymer can be further improved. It is possible to construct the drawing part with four or more stages, but from the viewpoint of the processing cost of the spinneret, the drawing part is 2 to
Most preferably, it is composed of three stages. Further, the inlet portion 6 of the inflow portion of the polymer discharge hole of the spinneret may be provided with an angle of 30 to 60 ° in order to improve the fluidity of the polymer.

The spinneret of the present invention is suitable for melt-spinning polyethylene terephthalate fibers, especially for melt-spinning polyethylene terephthalate fibers containing 1 to 10 parts by weight of titanium oxide per 100 parts by weight of polyethylene terephthalate. In particular, the effect can be more exerted in melt spinning of polyethylene terephthalate containing 2 to 10 parts by weight of titanium oxide.

In the production of polyethylene terephthalate fiber using the spinneret of the present invention, the characteristic of the winding speed at the time of melt spinning can be exhibited especially when winding at a speed of 5000 m / min or more.

[0015]

EXAMPLES Intrinsic viscosity (measured in o-chlorophenol at 25 ° C.) 0.65 from terephthalic acid and ethylene glycol using antimony trioxide as a polymerization catalyst according to a conventional method.
Of polyethylene terephthalate was obtained. At this time, 6% by weight of titanium oxide having an average primary particle size of 0.2 μm was added as a matting agent. The obtained polymer was melt-spun at a spinning temperature of 290 ° C. and a spinning speed of 6500 m / min to give 75 denier 3
A 6-filament fiber was used. Prior to spinning discharge, a mold releasing agent mainly containing dimethylsiloxane was applied to the spinneret surface according to a conventional method. Spinning was performed continuously for 4 days without cleaning the spinneret surface, and after removing the spinneret, the stain accumulated around the discharge hole was observed with a microscope, and the average height was read to evaluate the stain on the spinneret. Was done.

The spinneret used is stainless steel (SUS31
6) 36 circular discharge holes having a thickness of 15 mm and a diameter of 100 mm were made, and as shown in FIG. 2, the discharge hole outlet diameter D (mm), the discharge portion length L (mm), and the throttle portion 4 were formed.
It has various ejection holes represented by A, 4B and the ejection portion 5, and Table 1 shows the conditions and results. It should be noted that when the angle of the discharge portion 5 with respect to the central axis is a positive value, it means that the diameter is reduced in the discharge direction, and when the angle is a negative value, it means that the diameter is increased in the discharge direction. , The angle is 0 °
When it is, it means that the discharge portion has a straight shape. For example, the squeezing part of the spinneret in the practical example is composed of two stages, the squeezing part 4A is reduced in diameter in the polymer discharge direction by 35 ° with respect to the central axis of the discharge hole, and then the squeezing part 4B is discharged. 2 in the polymer discharge direction with respect to the central axis of the hole
The diameter is reduced at an angle of 5 ° and is in contact with the discharge part. Comparative Example 1 is a typical example of a conventional spinneret, which uses a spinneret having a straight discharge portion. In Comparative Examples 2 and 3, melt spinning is performed using a spinneret in which the discharge portion has a large diameter in the discharge direction up to the discharge hole outlet. In Comparative Example 3, 45 hours after the start of melt spinning, the periphery of the discharge hole became heavily soiled, and the polymer adhered to cause yarn breakage, making continuous winding impossible. Comparative Example 6
Shows an example of using a spinneret where the polymer discharge hole has a narrowed portion of 90 °, and the melt around the discharge hole becomes heavy 17 hours after the start of melt spinning, and the polymer adheres. This caused thread breakage, making continuous winding impossible.

[0017]

[Table 1]

[0018]

EFFECTS OF THE INVENTION The spinneret of the present invention has good uniformity of outflow of the discharge polymer, so that the amount of dirt deposits around the discharge hole of the spinneret is small and the cleaning period of the spinneret is extended as compared with the conventional spinneret. It is possible to reduce product loss,
The labor can be reduced, the cross-sectional shape and the thickness of the yarn are kept uniform, and the yarn quality is stable.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a polymer discharge hole of a spinneret of the present invention.

FIG. 2 is a partial cross-sectional view of a polymer discharge hole of the spinneret of the present invention.

FIG. 3 is a cross-sectional view of a polymer discharge hole of a conventional spinneret.

[Explanation of symbols]

 1: Spinneret 2: Polymer discharge hole 3: Inflow part 4: Throttling part 5: Discharge part 6: Inlet part of the inflow part

Claims (1)

[Claims] 1. A spinneret having a polymer discharge hole composed of an inflow portion, a throttle portion and a discharge portion which satisfy the following requirements (A) to (C). (A) The inflow portion is continuously reduced in diameter in the discharge direction at an angle of 0.2 to 3 ° with respect to the central axis of the discharge hole. (B) The diameter of the throttle portion is continuously reduced in the discharge direction at an angle of 20 to 50 ° with respect to the central axis of the discharge hole. (C) The diameter of the discharge portion is continuously reduced to the discharge hole outlet portion in the discharge direction at an angle of 3 to 20 ° with respect to the central axis of the discharge hole, and the length L of the discharge portion and the discharge hole outlet portion are reduced. L / D = 1 to 10 and the diameter D of the discharge hole outlet is 0.1 to 0.5 mm.