JP3180462B2 - Spinneret and melt spinning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spinneret and a melt spinning method, and more particularly to a spinneret and a melt spinning method used for melt spinning of polyethylene terephthalate fiber. During melt spinning, the production and stabilization of the periphery of the spinneret discharge hole, which is an obstacle to the production process, is suppressed, stabilizing the spinning production process, and maintaining a uniform cross-sectional shape and thickness of the yarn. , spun yarn quality is capable of providing a stable polyethylene terephthalate fiber
The present invention relates to a die and a melt spinning method.

[0002]

2. Description of the Related Art In the production of polyethylene terephthalate fiber by melt spinning, extruding into the atmosphere from a spinneret having a large number of small-diameter polymer discharge holes in order to impart a fiber morphology to a molten polymer is a process of spinning. This is the first step. Accordingly, a wide variety of geometries and spinnerets have been proposed and used, depending on the desired end product form. Furthermore, any spinneret is used for the adoption of ultrafine fibers having a diameter of less than 10 μm, irregularly shaped fibers having a complicated shape having a large number of protrusions, and high-speed spinning technology with a take-up speed exceeding 5,000 m / min. Spinning is a very important technical factor. Furthermore, the spinneret
It plays an important role in maintaining the stability of the yarn production process.

Usually, in the process of producing polyethylene terephthalate fibers, a spinneret in which the discharge portion 5 of the polymer discharge hole 2 has a cylindrical pore as shown in the sectional view of the spinneret in FIG. 3 is used. When using such a spinneret,
When continuous spinning is performed for a long time, additives, monomers, oligomers,
Alternatively, pyrolysis products and titanium oxide added as a matting agent adhere to the periphery of the polymer discharge hole, which is complicatedly changed and accumulated under the influence of heat, oxygen in the air, and the like. . For this reason, the releasability of the discharged polymer is deteriorated, and the spun yarn is bent, spiked, broken, and the like, and the yarn forming property becomes unstable. Therefore, when the accumulation amount of dirt around the polymer discharge hole increases, the melt spinning is interrupted,
The periphery of the spinneret discharge hole must be cleaned or the spinneret must be replaced. When the spinneret is cleaned or replaced, the production is naturally interrupted and requires a lot of labor, which greatly affects the production cost.

[0004] In order to suppress dirt around the polymer discharge hole of the spinneret and to improve the wiping property of the dirt, it is common practice to apply, for example, a polyorganosiloxane to which a heat-resistant agent is added to the spinneret surface. However, since the polyorganosiloxane is thermally denatured with time and dirt accumulates, it is necessary to occasionally scrape the dirt around the polymer discharge hole with a spatula-like tool and apply the polyorganosiloxane again, so-called die fixing work. 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 water vapor to suppress the growth of attached dirt is generally known.
In this method, a large investment is required because the apparatus is large, and an inert gas used for sealing is required, so that the operation cost is high, and the workability at the time of removing and attaching the pack and cleaning the spinneret surface is poor. Further, there is a problem that management for controlling physical properties of the spun yarn becomes complicated.

Japanese Patent Application Laid-Open No. 63-120109 discloses a method for suppressing the generation and growth of foreign matters deposited because a part of the discharge polymer adheres to the periphery of the discharge hole. A spinneret having a tapered hole whose diameter is increased at an angle of 3 to 25 ° with respect to the center axis of the discharge hole of the spinneret has been proposed. The publication discloses that by gradually widening the discharge holes, the property that a viscous substance extruded from the fine holes tends to spread beyond the diameter of the fine holes due to stress relaxation, that is, to reduce the so-called ballast effect and suppress the direct adhesion of the polymer. It is in. However, according to the test results of the present inventors, by adopting the shape, although the ballast effect is certainly reduced, the stain on the base is not reduced, and furthermore, the polyethylene containing the matting agent and the coloring agent is used. It has been found that when melt-spinning terephthalate or polyester having a low intrinsic viscosity, there is a problem that dirt is easily deposited.

[0006] When the present inventors repeated many experiments and observed the occurrence of dirt using a magnifying glass while melt-spinning, minute dirt was generated near the polymer discharge hole immediately after spinning was started. It has been found that the sublimate from the polymer adheres to the minute dirt, or the polymer spread by the ballast effect adheres, and the dirt grows. The fine stains generated immediately after the start of the spinning were mainly titanium oxide added as a matting agent to polyethylene terephthalate or a modified product of an antimony compound as a polymerization catalyst.
Furthermore, the first contamination on the periphery of the polymer discharge hole can be greatly reduced by melt-spinning using a spinneret with a special shape, and the growth of dirt on the periphery of the spinneret discharge hole is dramatically reduced. I found what I could do.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems in the prior art, and to provide a spinneret capable of stabilizing a yarn production process for a long period of time and reducing the frequency of a surface cleaning operation of a spinneret. It is to provide a spinning method.

[0008]

An object of the present invention is to use a spinneret having a polymer discharge hole composed of an inflow portion, a throttle portion and a discharge portion, which satisfies the following requirements (A) to (D). Achieved by: (A) the inflow portion is parallel to the central axis of the discharge hole, or 3
径 The diameter is continuously reduced in the discharge direction at the following angles. (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 exit 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 exit portion Is L / D = 1 to 10, and the diameter D of the outlet of the discharge hole is 0.1 to 0.5 mm. (D) Chamfer length d = 3 expressed by the following equation at the outlet of the discharge hole
A chamfer of ３０30 μm is provided. Chamfer length d = (DD ′) / 2 D ′: minimum diameter of polymer discharge hole D: diameter of discharge hole outlet

Melt spinning is performed using a conventional spinneret having a discharge port 2 as shown in FIG. 3 comprising a polymer inflow section 3, a throttle section 4, and a polymer discharge section 5 having a cylindrical pore. In the manufacturing method, the shear velocity rapidly increases when the molten polymer flows into the discharge of the spinneret, and the flow of the polymer becomes extremely unstable, so that a flow velocity distribution occurs in the polymer. In the case where polyethylene terephthalate contains titanium oxide, the titanium oxide is concentrated on the wall of the hole having a low polymer flow rate in the discharge hole of the spinneret and causes contamination. This titanium oxide concentrate exudes from the edge of the outlet of the discharge hole,
It becomes minute dirt. The sublimate in the discharge polymer adheres to the minute dirt, or the discharge polymer spread by the ballast effect adheres, and the dirt grows rapidly. Some of the conventionally used spinnerets include a polymer inflow section 3 and a polymer discharge section 5 as shown by a polymer throttle section 4 in FIG.
In some cases, one or several conical apertures are provided between them. If the discharge part 5 communicating with the discharge hole outlet part is cylindrical or has a large diameter in the discharge direction, the flow of the polymer is extremely unstable. The exact reason is not clear,
Unless the diameter of the discharge portion communicating with the discharge hole exit portion like the spinneret of the present invention is reduced in the discharge direction and high pressure is not applied, particles such as additives and foreign substances in the polymer permeate the edge of the discharge hole exit portion. It is inevitable that it will be discharged and become minute dirt. In addition, the chamfer is not particularly applied to the outlet of the discharge hole,
In the case of sharp edges, dirt is particularly likely to occur. Spinning clues alloy of the present invention, the discharge portion to the central axis of the discharge hole, it is necessary to diameter of the discharge direction by 3 to 20 ° angle. Preferably, with respect to the central axis of the discharge hole, 6
It is an angle of ゜ 10 °. If the angle of the discharge section is smaller than 3 °, the flow of the polymer in the discharge hole will not be smooth, and the flow stabilization effect of the discharge polymer will be small. The angle of the discharge hole is 2
If it is larger than 0 °, the back pressure of the base decreases, and the weighability of the polymer decreases.

In FIG. 2, the ratio L / D of the length L of the discharge portion of the discharge hole to the diameter D of the outlet portion of the discharge hole needs to be 1 to 10. Preferably, L / D is 2-4. L / D is 1
If the pressure is less than 1, when the pressure loss in the die hole becomes small, the discharge amount of the polymer becomes unstable. On the other hand, if the L / D exceeds 10, the flow resistance of the polymer is too large and the back pressure of the spinneret increases, and the spinneret cannot withstand the pressure. The diameter D of the outlet of the discharge hole
Is required to be 0.1 to 0.5 mm. Preferably, the diameter D of the outlet of the discharge hole is 0.25 to 0.5.
35 mm. Here, the diameter D of the outlet of the discharge hole is the diameter of a portion of the spinneret in contact with the surface on the polymer discharge side, and the diameter of the outlet of the discharge hole includes the chamfered portion. If the diameter D of the outlet of the discharge hole is less than 0.1 mm, it is difficult to accurately process the inner wall of the discharge hole, and it is difficult to obtain a uniform yarn during melt spinning. on the other hand,
If it exceeds 0.5 mm, it is difficult to obtain a polyester fiber having no thread spots.

The inflow portion 3 of the polymer discharge hole of the spinneret shown in FIG.
Needs to be reduced in diameter in parallel with the central axis of the discharge hole or continuously in the discharge direction at an angle of 3 ° or less. Preferably, the diameter is reduced at an angle of 0.2 to 2 ° in the ejection direction.
When the diameter of the inflow portion is increased in the discharge direction, the inflow of the molten polymer tends to be unstable. By slightly reducing the diameter in the discharge direction, the flow of the molten polymer becomes extremely smooth.
When the diameter of the inflow portion is reduced at an angle larger than 3 ° with respect to the center 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. It is intolerable and the spinneret may deform.

[0012] The throttle portion 4 of the polymer discharge hole of the spinneret of FIG.
It is necessary to reduce the 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 center axis of the discharge hole. If the angle of the constricted portion 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 changes, and if it is smaller than 20 °, the flow resistance of the polymer becomes large, so the back surface of the base is closed. The pressure increases and the diameter of the inflow section must be reduced. Further, it is preferable that the aperture portion is constituted by two or more steps as shown in FIG. In forming the throttle portion in two or more stages, it is preferable that the angle with respect to the center axis of the discharge hole in the polymer discharge direction is small. For example, the throttle 4A in FIG. 2 is reduced in diameter in the polymer discharge direction at an angle of 35 ° with respect to the central axis of the discharge hole, and then the throttle 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. The drawing portion can be composed of four or more stages, but from the viewpoint of the processing cost of the spinneret, the drawing portion has a thickness of 2-3.
Most preferably, it is composed of steps.

[0013] spinning clues alloy of the present invention should be chamfered in the chamfer length d = 3 to 30 .mu.m, represented by the following formula discharge hole outlet is subjected. Chamfer length d = (DD ′) / 2 D ′: minimum diameter of polymer discharge hole D: diameter of discharge hole outlet

When spinning is performed for a long time, the periphery of the outlet of the spinneret is shaved non-uniformly by the polymer, and the fineness variation between the single yarns of the obtained yarn and the unevenness in the longitudinal direction of the fiber gradually occur. Become larger. Therefore, it cannot withstand long-term repeated use. In addition, if the outlet portion of the discharge hole has a sharp edge, the surface energy of the edge portion becomes high, and dirt tends to adhere. Concentration of particles such as titanium oxide and foreign substances added to the polymer that causes contamination is caused by the shape of the inflow portion, the throttle portion, and the discharge portion of the polymer discharge hole as requirements (A) to (C). However, it is possible to further reduce the contamination of the spinneret by chamfering the outlet of the discharge hole. By applying a chamfer of 3 to 30 μm to the outlet of the discharge hole, the change over time of the outlet of the discharge hole is significantly reduced, the service life of the spinneret can be extended, and the generation of stains on the spinneret can be further reduced. Becomes possible. If the chamfer length d at the outlet of the discharge hole is less than 3 μm, the effect of extending the service life of the spinneret and the effect of suppressing adhesion of dirt cannot be satisfied. On the other hand, if the chamfer length d exceeds 30 μm, the flow of the discharged polymer becomes unstable, and the unevenness of the obtained fibers in the longitudinal direction increases. More preferably, the chamfer length d
Is 7 to 12 μm. Preferably, the chamfering depth 1 reaches the inside of the discharge hole to a range of 0.5 to 2 times the chamfering length d.

As a specific method of chamfering, there is a method in which the outlet portion of the discharge hole is pressed or a method in which fine steel particles dispersed in a liquid are sprayed with water pressure and compressed air to remove the material. It is preferable to have a smooth curve that protrudes inside the discharge hole from the inside of the discharge hole to the outlet. By repeating the pressing several times, preferably two or three steps, a pseudo curved portion can be provided.

Further, in order to improve the flowability of the polymer, 30 to 6 holes are provided at the inlet 6 of the inlet of the polymer discharge hole of the spinneret.
An angle of 0 ° can also be provided. The melt spinning method of the present invention requires the use of the spinneret of the present invention described above.
But melt spinning of polyethylene terephthalate fiber,
In particular, it is suitable for melt spinning of polyethylene terephthalate fibers containing 1 to 10 parts by weight of titanium oxide with respect to 100 parts by weight of polyethylene terephthalate. In particular, the effect can be further enhanced in melt spinning of polyethylene terephthalate containing 2 to 10 parts by weight of titanium oxide. Ma
In addition, the melt spinning method of the present invention can exert its characteristics in the production of polyethylene terephthalate fiber, particularly when winding at a speed of 5000 m / min or more.

[0017]

【Example】

Examples 1-4, Comparative Examples 1-5 Using antimony trioxide as a polymerization catalyst according to a conventional method, polyethylene terephthalate having an intrinsic viscosity (measured in o-chlorophenol at 25 ° C) of 0.65 was obtained from terephthalic acid and ethylene glycol. 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 subjected to melt spinning at a spinning temperature of 300 ° C. and a winding speed of 6000 m / min to obtain fibers of 75 denier and 36 filaments. Before the spinning discharge, a release agent mainly composed of dimethylsiloxane was applied to the surface of the die according to a conventional method. The spinneret used was made of stainless steel (SUS316) having a thickness of 15 mm, a diameter of 100 mm, and 36 circular discharge holes perforated. As shown in FIG. 2, the discharge hole outlet diameter D (mm), the discharge part length L (mm), throttle unit 4A, 4
B, ejection part 5, chamfer length d (μm), chamfer depth l
(Μm).
Shows the conditions. When the angle of the discharge unit 5 with respect to the center axis is a positive value, it indicates that the diameter is reduced in the discharge direction, and when the angle is a negative value, it indicates that the diameter is increased in the discharge direction. , When the angle is 0 °, it indicates that the discharge portion has a straight shape. Continuous spinning without cleaning the spinneret surface for 4 days. After removing the spinneret, observe the dirt deposited around the discharge hole with a microscope, read the average height, and evaluate the dirt on the die. Was performed. In addition, the single yarn fineness variation of the yarn wound immediately before the end of the spinning was measured. Table 2 shows the results.

The drawing portion of the spinneret according to the first embodiment is composed of two stages, and the drawing portion 4A is reduced in diameter at an angle of 35 ° to the polymer discharge direction with respect to the center axis of the discharge hole. The diameter was reduced at an angle of 25 ° to the polymer discharge direction with respect to the center axis of the discharge hole, and the diameter was connected to the discharge portion. In the spinneret of Example 2, the diameter D of the outlet of the discharge hole was 0.20 (mm). The spinneret of Example 3 had an L / D of 7. The spinneret of Example 4 had a single-stage drawing portion.

Comparative Example 1 is a typical example of a conventional spinneret, in which a spinneret having a straight discharge portion is used. Comparative Example 2 is a spinneret in which the discharge section is increased in diameter in the discharge direction to the discharge hole outlet, and is 1 point after the start of melt spinning.
After 7 hours, the periphery of the discharge hole became heavily stained, and the polymer adhered, causing thread breakage, making it impossible to continuously wind up. In Comparative Example 3, melt spinning was performed using a spinneret having an L / D outside the scope of the present invention. Comparative Example 4 is an example in which the narrowed portion of the polymer discharge hole is 90 ° and a spinneret having substantially no narrowed portion is used. Comparative Example 5 is an example in which the shape of the inflow portion, the throttle portion, and the discharge portion satisfies the constitutional requirements of the present invention, but uses a spinneret without chamfering.

[0020]

[Table 1] Next, in the ferrules of Examples 1 to 4 and Comparative Examples 1, 3, and 5, a polymer obtained by adding 2.5% by weight of titanium oxide having an average primary particle size of 0.2 μm to polyethylene terephthalate having an intrinsic viscosity of 0.65 was used. The melt spinning was performed at a spinning temperature of 300 ° C. and a winding speed of 6000 m / min to obtain a fiber of 75 denier and 36 filaments. The spinneret surface was cleaned every four days after the start of spinning, and spinning was continued for 30 days. At this time, even when the spinneret stain is not generated for comparison,
The spinneret surface was cleaned. The yarn fineness variation of the yarn obtained immediately before the spinneret surface cleaning operation on day 28 of the spinning was measured. The long-term repeated use was evaluated in comparison with the variation in single-filament fineness of the yarn obtained before the cleaning operation on the fourth day from the start of spinning. Table 2 shows the results.

[0021]

[Table 2] In Example 1, the change over time of CV (%) was as small as 0.2 and the foreign matter deposited on the base was small. In Example 2, the CV (%) after spinning for 4 days was as small as 1.1, and the change with time was 0.1%.
4 and less. In Example 3, the CV (%) after 4 days was as small as 0.8, and the change with time was small. Example 4 shows CV (%)
With time is as small as 0.2. In Comparative Example 1, the CV (%) after 4 days of spinning was as large as 2.0, and the change over time in CV (%) was as large as 1.4. In addition, 30
(Μm). Comparative Example 2 shows CV (%) after spinning for 4 days.
Was 3.9, which was large, and could not be wound up 17 hours after the start of spinning due to thread breakage due to dirt. In Comparative Example 3, the number of foreign matters deposited on the die surface was as small as 7 (μm), but CV after spinning for 4 days.
(%) Is as large as 2.2. Comparative Example 4 shows CV after spinning for 4 days.
(%) Is as large as 4.1, and foreign matter deposited on the base is 52 (μ).
m). In Comparative Example 5, the foreign matter deposited on the die surface was as small as 6 (μm), and the CV (%) after 4 days of spinning was as small as 0.8.
The change with time of CV (%) is as large as 2.2.

[0022]

According to the melt spinning method of the present invention, since the uniformity of the discharge of the discharged polymer is good, dirt deposits around the spinneret discharge hole are small, and the cleaning cycle of the spinneret is shorter than that of the conventional melt spinning method. Since the length can be extended, the loss of the product and the labor can be reduced, and the cross-sectional shape and thickness of the yarn are kept uniform, and the yarn quality is stabilized.

[Brief description of the drawings]

FIG. 1 is a sectional view of a polymer discharge hole of a spinneret used in a melt spinning method of the present invention.

FIG. 2 is a partial sectional view of a polymer discharge hole of a spinneret used in the melt spinning method of the present invention.

FIG. 3 is a sectional view of a polymer discharge hole of a spinneret used in a conventional melt spinning method.

[Explanation of symbols]

 1: spinneret 2: polymer discharge hole 3: inflow section 4: throttle section 5: discharge section 6: inlet section of inflow section 7: chamfered section

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-120109 (JP, A) JP-A-61-138719 (JP, A) JP-A-6-25906 (JP, A) JP-A-5-205 132810 (JP, A) JP-A-60-181311 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D01D 4/00-4/08 D01F 6/62 301-308

Claims (2)

(57) [Claims] 1. A spinneret having a polymer discharge hole composed of an inflow section, a throttle section and a discharge section satisfying the following requirements (A) to (D). (A) the inflow portion is parallel to the central axis of the discharge hole, or 3
The diameter is continuously reduced in the discharge direction at an angle of less than or equal to °. (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 center axis of the discharge hole. (C) The diameter of the discharge portion is continuously reduced to the discharge hole exit 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 exit portion Is L / D = 1 to 10, and the diameter D of the outlet of the discharge hole is 0.1 to 0.5 mm. (D) Chamfer length d = 3 expressed by the following equation at the outlet of the discharge hole
A chamfer of ２０20 μm is provided. Chamfer length d = (DD ′) / 2 D ′: minimum diameter of polymer discharge hole D: diameter of discharge hole outlet 2. A method for melt-spinning polyethylene terephthalate , comprising using the spinneret according to claim 1.