JPH09195119A - Spinneret for melt spinning - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit the deterioration of filament spinning properties and drawing performance caused by thermal degradation of thermoplastic resin, while the polymer abnormally stays at the inlet of the spinneret by providing a chokebore part in the polymer melt-flowing hole communicating with the orifices on the spinneret. SOLUTION: A front plate 3 having polymer melt-flowing hole communicating to the orifices 5 bored on the spinneret plate 4 is set so that it comes into contact with the upper face of the spinneret 4 and a chokebore part 7 is formed in the polymer melt-flowing hole 6 to minimize the difference in the hole diameter between the front flow plate 8 and the inlet of the spinneret 9. A thermoplastic resin of high viscosity, as much as 3,000-10,000 poise at 290 deg.C, can be melt-extruded smoothly into filaments.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melt-spinning die used for melt-spinning a thermoplastic resin.

[0002]

2. Description of the Related Art Conventionally, as a spinneret for melt spinning using a thermoplastic resin, a spinneret having a spinning hole under a straightening plate as shown in FIG. 3 has been used. Further, as a spinneret for producing a mixed yarn of different fineness, Japanese Patent Laid-Open No. 58-174612 discloses a spinneret plate as shown in FIG.
Between the (12) and the current plate (13), contact the upper surface of the mouth plate (12),
Front plate (15) with a melt flow hole communicating with the spinning hole (14)
A spinneret for melt-spinning has been proposed. In this melt-spinning die, the hole diameter of the outflow portion (16) from the front plate is extremely smaller than that of the inflow portion (17) into the die plate. For this reason, when melt-spinning a high-viscosity thermoplastic resin, the thermoplastic resin causes abnormal retention at the upper end (18) of the die plate inflow part and is thermally deteriorated by a long heat history, resulting in spinnability and stretching. There was a problem that sex deteriorates.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned abnormal retention at the inflow portion of the die plate and the deterioration of the spinnability and stretchability due to the thermal deterioration of the thermoplastic resin, and makes it possible to efficiently use a high-viscosity thermoplastic resin. It is an object of the present invention to provide a spinneret for melt spinning which can be well melt-spun.

[0004]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the inventors changed the shape of the melt flow hole of the front plate in contact with the upper surface of the die plate having the discharge hole. By doing so, it was found that abnormal retention at the inflow portion of the spinneret plate can be eliminated and efficient melt spinning can be achieved, and the present invention has been achieved.

The gist of the present invention is as follows. (1) A spinneret used for melt spinning of a thermoplastic resin, the spinneret plate having a discharge hole formed therein, and in contact with an upper surface of the spinneret plate,
A melt-spinning die comprising a front plate having a melt flow hole communicating with a discharge hole, wherein a narrowed portion is provided in the melt flow hole of the front plate. (2) The spinneret for melt spinning according to (1) above, wherein the first downstream taper angle θ ₁ and the second downstream taper angle θ ₂ of the narrowed portion in the melt flow hole satisfy the following equation. θ ₁ = 20 ° to 90 ° θ ₂ = 60 ° to 150 ° θ ₁ <θ ₂ (3) Length (Lmm) of the minimum hole diameter part of the throttle part and its diameter (D
mm) to satisfy the following numerical values, the spinneret for melt spinning according to the above (1) or (2). L / D = 0.3 to 3.0 (4) Melt spinning of a thermoplastic resin having a melt viscosity of 3000 to 10000 poise during spinning is carried out by melt spinning.
The spinneret for melt spinning according to any one of (3).

[0006]

1 is an overall view of a melt-spinning die of the present invention, and FIG. 2 is a detailed partial enlarged view of the melt-spinning die of the present invention. FIG. 1 shows the spinneret for melt spinning of the present invention.
And it demonstrates using FIG. The spinneret for melt spinning of the present invention is in contact with a die plate (4) provided with a discharge hole (5) and an upper surface of the die plate (4), and a melt flow hole (6) communicating with the discharge hole (5). It consists of a perforated front plate (3), the melt flow hole (6) in the front plate (3) is provided with a throttle part (7), and the front plate outflow part (8) and the mouth plate inflow part (9 ) Is smaller. The narrowed portion (7) in the melt-spinning die of the present invention means that the cross-sectional area (S) of the narrowed portion (7) is the cross-sectional area of the melt inflow portion and the melt outflow portion.
It refers to the part that is smaller than (S ₁ , S ₂ ). In such a die, the melt flows through the melt flow hole (6) of the front plate (3), is rectified by the throttle part (7) and flows into the base plate (4), but the front plate outflow part (8) and the base Since the hole diameter difference of the plate inflow part (9) is small, it flows into the die plate without causing abnormal retention at the die plate inflow part as seen in the conventional example.

Next, since the melt rectified in the throttle portion (7) flows into the die plate (4) without causing abnormal retention, the taper below the throttle portion has two stages, and the first downstream taper angle θ It is preferable that ₁ and the second downstream taper angle θ ₂ satisfy the range of the following formula. θ ₁ = 20 ° to 90 ° θ ₂ = 60 ° to 150 ° θ ₁ <θ _{2 If} θ ₁ is less than 20 °, the melt causes abnormal retention in the second downstream taper portion, and if it exceeds 90 °. , The molten liquid causes abnormal retention in the first downstream taper portion. Also, θ ₂ is 6
If it is less than 0 °, the molten liquid causes abnormal retention in the inflow part of the spinneret plate, and if it exceeds 150 °, the hole diameter of the inflow part of the spinneret plate becomes large, so that the number of spinning holes is limited or the front plate (3) Since it becomes thicker, it becomes difficult to insert it into the mouthpiece holder.

From the above problems, θ ₁ and θ ₂ are preferably θ ₁ = 30 ° to 70 ° and θ ₂ = 70 ° to 120.
°, more preferably θ ₁ = 40 ° to 60 °, θ ₂ = 8
It is 0 ° to 100 °. Further, the taper under the narrowed portion does not have to be limited to two stages, and there is no problem even if it is more than two stages. If a taper with two or more steps is provided, θ ₂
Is the taper angle of the final taper.

It is preferable that the ratio of the length (Lmm) of the smallest hole diameter portion of the narrowed portion to the diameter (Dmm) thereof satisfies the range of the following formula. L / D = 0.3 to 3.0 When L / D satisfies the range of the above formula, there is a rectifying effect to the melt and an appropriate back pressure can be given.

The melt-spinning die of the present invention is a spinneret used for melt-spinning of a thermoplastic resin. For melt-spinning of a thermoplastic resin having a melt viscosity of 3,000 to 10,000 poise at 290 ° C., which tends to cause abnormal retention, More useful. In the present invention, the thermoplastic resin means a melt-spinnable polymer such as polyester, polyamide and polyolefin. These thermoplastic resins may contain a small amount of additives such as matting agents, colorants, stabilizers and antistatic agents.

Further, the shape of the spinning hole formed in the spinneret plate is
The shape is not particularly limited, and any irregular cross section such as a round cross section, three lobes, and six lobes may be used.

[0012]

The present invention will be specifically described below with reference to examples. In addition, each characteristic value in the examples was obtained by the following method.

(A) Melt viscosity Using a Shimadzu high-performance flow tester, 290 ° C.
It was measured at.

(B) Spinning yarn breakage count The spinning yarn breakage count is 6 kg of undrawn yarn package 5000.
The number of yarn breaks during spinning that occurred before the individual pieces were obtained.
The spinnability was determined as follows. Number of times of spinning yarn breakage Judgment of spinnability 0 to 10 times ◎ (very good) 11 to 20 times ○ (good) 21 to 30 times Δ (somewhat good) 31 times or more × (poor)

(C) Number of drawn yarn breaks The number of drawn yarn breaks was defined as the number of yarn breaks during drawing that occurred until 3000 3000 kg drawn yarn packages of 2 kg were obtained.
The determination of the stretchability was as follows. Number of times of draw yarn breakage Judgment of drawability 0 to 10 times ◎ (very good) 11 to 20 times ○ (good) 21 to 30 times Δ (somewhat good) 31 times or more × (bad)

Example 1 Polyethylene terephthalate having a melt viscosity at 290 ° C. of 5000 poise was melt-spun using the spinneret shown in FIG. The undrawn yarn obtained has an elongation of 35%.
Stretching was carried out by a conventional method at a stretching ratio of about the same. The spinning conditions and the drawing conditions were as follows. Spinning conditions Spinning temperature: 295 ° C. Number of holes in spinneret: 36 Hole diameter of spinneret: 0.23 mm Discharge rate: 36.0 g / min Spinning speed: 1500 m / min First downstream taper angle θ ₁ : 40 ° Second downstream taper Angle θ ₂ : 90 ° Ratio (L / D) of length (Lmm) and diameter (Dmm) of the minimum hole diameter part of the narrowed part: 1.0 Drawing conditions Hot roller temperature: 86 ° C Hot plate temperature: 140 ° C Drawing Speed: 750 m / min The number of yarn breakages during spinning and drawing was 4 and 5, and the spinnability and drawability were very good.

Comparative Example 1 Using the spinneret for melt spinning shown in FIG. 4, spinning and drawing were performed under the same conditions as in Example 1. In this case, the number of yarn breakages frequently occurred at 35 times and 37 times during spinning and drawing, and the spinnability and drawability were very poor. Further, a blackened deteriorated polymer due to abnormal retention was confirmed in the spinneret inflow part (part (18) in FIG. 4) after completion of spinning.

Example 2 Using the spinneret for melt spinning shown in FIG. 1, a first downstream taper angle θ
₁ , except that the second downstream taper angle θ ₂ , the ratio of the length (L mm) to the diameter (D mm) of the minimum hole diameter portion of the throttle portion, and the melt viscosity at 290 ° C. are variously changed as shown in Table 1. Spinning and drawing were performed under the same conditions as in Example 1. The spinnability and drawability at this time are also shown in Table 1.

As is clear from Table 1, the spinnability and the drawability were very good or good, or slightly good at the levels of Nos. 1 to 9 which were the ranges of the present invention.

[0020]

[Table 1]

[0021]

EFFECTS OF THE INVENTION According to the present invention, it is possible to eliminate abnormal retention in the inlet portion of the die plate and deterioration of spinnability and stretchability due to thermal deterioration of the thermoplastic resin. It becomes possible to perform melt spinning well.

[Brief description of the drawings]

FIG. 1 is an overall schematic view of a melt-spinning die of the present invention.

FIG. 2 is a detailed partial enlarged view of the spinneret for melt spinning of the present invention.

FIG. 3 is a partially enlarged view of a conventional melt-spinning die.

FIG. 4 is a partially enlarged view of a conventional melt-spinning die.

[Explanation of symbols]

1 ・ ・ Mouth holder 2 ・ ・ Rectifier plate 3 ・ ・ Front plate 4 ・ ・ Mouth plate 5 ・ ・ Discharge hole 6 ・ ・ Melted liquid flow hole 7 ・ ・ Throttle part 8 ・ ・ Front plate outflow part 9 ・ ・ Mouth plate inflow Part θ ₁・ First downstream taper angle θ ₂・ Second downstream taper angle L ・ ・ Length of the minimum hole diameter part of the throttle part D ・ ・ Diameter of the minimum hole diameter part of the throttle part S ・ ・ of the minimum hole diameter part of the throttle part Cross-sectional area S ₁ · Cross-sectional area of melt inflow part S ₂ · Cross-sectional area of melt outflow part 11 · · Spindle holder 12 · · Spindle plate 13 · · Straightening plate 14 · · Spindle hole 15 · · Front plate 16 · · Outflow part from the front plate 17 ・ ・ Inflow part to the mouth plate 18 ・ ・ Upper end of the mouth plate inflow part

Claims (4)

[Claims] 1. A spinneret used for melt spinning of a thermoplastic resin, wherein a spinneret plate having a discharge hole formed therein, and a melt flow hole which is in contact with the upper surface of the spinneret plate and communicates with the discharge hole are provided. A melt-spinning die comprising a front plate, wherein a narrowed portion is provided in a melt flow hole in the front plate. 2. The spinneret for melt spinning according to claim 1, wherein the first downstream taper angle θ ₁ and the second downstream taper angle θ ₂ of the narrowed portion in the melt flow hole satisfy the following equation. θ ₁ = 20 ° to 90 ° θ ₂ = 60 ° to 150 ° θ ₁ <θ ₂ 3. The spinneret for melt spinning according to claim 1, wherein the ratio of the length (L mm) of the smallest hole diameter portion of the narrowed portion to the diameter (D mm) thereof satisfies the following numerical values.
L / D = 0.3-3.0 4. The melt-spinning die according to claim 1, wherein a thermoplastic resin having a melt viscosity at 290 ° C. of 3000 to 10000 poise is melt-spun.