JPH0241408A - Melt spinning - Google Patents

Abstract

PURPOSE:To obtain yarn having excellent passing properties of process and no yarn unevenness by sealing a sealing material consisting of a specific aromatic compound in the interior of pack of spinneret heated to a spinning temperature, fixing the pack to a spinning device, introducing a molten thermoplastic polymer and spinning. CONSTITUTION:In subjecting a thermoplastic fiber-forming synthetic polymer (e.g., nylon 6) to melt spinning, a pack 1 of spinneret is heated at least to a spinning temperature, then a substance (e.g., N-butylbenzenesulfonamide) shown by formula I (R is 3-12C aliphatic hydrocarbon) and/or formula II is sealed in space 9 in the interior of the pack of spinneret, the pack 1 of spinneret in which the sealing substance is sealed is fixed to a spinning device, a molten polymer is introduced from a molten polymer induction hole 4 and spun from the spinneret 7 having plural spinning holes.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for melt spinning a thermoplastic fiber-forming synthetic polymer.

(Prior art) When melt-spinning a thermoplastic fiber-forming synthetic polymer,
If air exists in the flow path of the molten polymer, it becomes air bubbles and gets mixed into the molten polymer, causing thread breakage at the start of spinning. In particular, if air exists inside the spinneret pack, the air becomes bubbles and is gradually discharged from the inside of the spinneret pack over a long period of time, resulting in intermittent yarn breakage even after a long period of time has passed after the start of spinning. do. For this reason, when synthetic fibers are melt-spun, the spun fibers are generally used as waists during the period during which yarn breakage occurs after the start of spinning, and once yarn breakage no longer occurs, the resulting fibers are treated as regular products. Ta. However, since the spun fibers are used as waist, there is a problem in that not only the operability is significantly reduced (but also the cost is increased due to a decrease in product yield).

Furthermore, even if the spun fibers are released for a predetermined period of time after the start of spinning, small air bubbles that do not cause yarn breakage during spinning are gradually discharged over a very long period of time.

There has been a problem in that thread breakage occurs in post-processes such as drawing, or thread unevenness occurs even though thread breakage does not occur.

Japanese Patent Publication No. 40-1810 describes (1) a compound that generates inert gases such as carbon dioxide, nitrogen, hydrogen, and water vapor by heat inside the spinneret pack and leaves no reaction residue during melt spinning of a synthetic polymer; Alternatively, a method is disclosed in which a compound is added that can be easily filtered with a filter or the like even if a residue remains.

This method is aimed at preventing the molten polymer from being decomposed by oxygen or causing irregular polymerization inside the nozzle pack, and this method prevents the molten polymer from deteriorating. However, the inert gas generated becomes bubbles and mixes into the molten polymer,
It is not possible to prevent yarn breakage from occurring at the start of spinning.

In addition, Japanese Patent Publication No. 44-73784 discloses that as a method of preventing air bubbles from being mixed into the molten polymer at the start of spinning, gas present in the path of the spinning solution is sucked out when starting spinning in melt spinning. A method of evacuation by means of an apparatus is disclosed. but.

This method requires equipment such as a gas suction device.

Moreover, it has the disadvantage that the spinning device becomes complicated.

(Problems to be Solved by the Invention) The present invention enables stable continuous spinning after starting melt spinning of a thermoplastic fiber-forming synthetic polymer, and provides excellent process passability in subsequent steps. The object of the present invention is to provide a method that can produce fibers that are free from yarn unevenness defects.

(Means for Solving the Problems) As a result of intensive studies, the present inventors found that the above-mentioned problems can be solved by sealing a specific substance inside the spinneret pack and spinning it.1 The present invention has been reached.

That is, in the present invention, in melt spinning a thermoplastic fiber-forming synthetic polymer, the following general formula (A) and/or (
Summary of a melt spinning method characterized in that the substance represented by B) is encapsulated, and then the spinneret pack encapsulated with the encapsulated substance is attached to a spinning device) and a molten polymer is introduced to start spinning. That is.

[R is a saturated or unsaturated aliphatic hydrocarbon group having 3 to 12 carbon atoms. ] The following is a detailed explanation of the present invention.

In the present invention, the N-alkylbenzenesulfonic acid amide represented by the general formula (A) and/or the one-bite formula (B)
A p-hydroxybenzoic acid ester represented by is used as an encapsulating material. Examples of the N-alkylbenzenesulfonamide include N-propylbenzenesulfonamide, N-
Examples include butylbenzenesulfonamide, N-hexylhenzenesulfonamide, and the like. In addition, p-hydroxybenzoic acid esters include propyl-p-hydroxybenzoate, butyl-p-hydroxybenzoate,
Examples include lauryl-p-hydro-1-dibenzoet.

Examples of thermoplastic fiber-forming synthetic polymers in the present invention include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and poly p-ethylene oxyhensoate, nylon 6° nylon 66, and nylon 46.
．． Examples include polyamides such as nylon 12, and polyolefins such as polyethylene and polypropylene.

Next, a melt spinning method according to the present invention will be explained.

FIG. 1 is a cross-sectional view of an example of a spinneret pack for carrying out the method of the present invention. In Fig. 1, 1 is the spinneret pack body, 2 is the top cap, 3 is a ring for tightening the top cap, 4 is a hole dedicated to the molten polymer, 5 is a filter medium, 6 is a breaker play 1, and 7 is a plurality of 8 is a backing, and 9 is a space inside the spinneret pack.

What is the space inside the spinneret pack in the present invention?

Molten polymer introduction hole 4, top cap 2 and filter medium 5
, the entire path of the molten polymer in the breaker plate 6, and the area between the breaker plate 6 and the spinneret 7.

In the method of the present invention, the spinneret pack is preheated to at least the spinning temperature, and then the encapsulated substances (A) and/or (B) are introduced through the molten polymer introduction hole 4 of the spinneret pack.
is introduced into the space 9 inside the pack. Note that when charging the encapsulating substance, it is preferable to preheat the encapsulating substance to a temperature of about 100° C. above room temperature.

If the temperature is too low, the encapsulated substance becomes viscous, making it difficult to encapsulate it inside the pack, which is not preferable. Furthermore, if the temperature is too high, the viscosity of the encapsulated substance decreases and the fluidity increases, but the operation of charging the encapsulated substance becomes dangerous.

In the method of the present invention, to start spinning, the spinneret pack containing the encapsulated substance is attached to the spinning device, the molten polymer is introduced into the spinneret pack, spinning is started, and the spun fibers are then discharged. After that, start winding.

The amount of encapsulated material to be loaded is typically between 0.01 and 0.00 times the weight of the encapsulated material occupying space within the spinneret pack.
A range of about 0.08 times is appropriate. If it is less than 0.01 times, the effect of preventing the air existing inside the spinneret pack from forming bubbles and mixing into the molten polymer, resulting in yarn breakage and yarn unevenness, will be insufficient.

Moreover, if the amount is more than 0.08 times, gasified enclosed substances may blow out from the spinneret pack when the spinneret pack is attached to the spinning device, worsening the working environment, or stain the spinneret surface and cause yarn breakage. This is not desirable because it causes

The discharge time of the spun fibers from immediately after the start of spinning until the start of winding is 9 Usually, the discharge amount is 0.03 to 0.1 times the weight of the molten polymer occupying the space inside the spinneret pack.
It is appropriate to set the time to a range of about 0 times. 0.
If it is shorter than 0.03 times, it is difficult to prevent air bubbles from being mixed into the molten polymer. Further, if the length is longer than 0.10 times, the inclusion of air bubbles can be prevented, but the amount of fibers forming the waist becomes larger than necessary, which is uneconomical.

Note that the discharge in the method of the present invention is normally carried out.

This is carried out under steady discharge rate conditions, but if the discharge rate of the molten polymer is increased compared to the steady state, or if it is increased/decreased intermittently or temporarily stopped, gas may become bubbles and get mixed into the molten polymer. The effect of the present invention in preventing this is further improved.

(Function) According to the method of the present invention, it is possible to prevent the deterioration of the molten polymer due to the air inside the spinneret pack and the mixing of air bubbles into the molten polymer. The reason for this is not clear, but the air inside the spinneret pack is replaced by the gasified filler material, and most of the gas is then expelled out of the pack by the molten polymer introduced inside the pack, leaving some of the gas remaining. This is believed to be because the gas dissolves in the molten polymer.

(Example) Hereinafter, the method of the present invention will be specifically explained based on Examples.

Example 1 The relative viscosity is 3.4 (using 96% by weight concentrated sulfuric acid as the solvent).

Nylon 6 (measured at a concentration of 1 g/dl and a temperature of 25°C)
After melting the chip (denoted as N6) using an extruder type melt spinning device, the spinning temperature (cutter temperature) was 250°C.

35 through a spinneret with 46 spinning holes of circular cross section.
Spun at a discharge rate of 0 g/min, taken in a cooling water bath at a temperature of 10°C to cool it, and then continuously used a hot water bath at a temperature of 90°C and a dry air bath at a temperature of 200°C without first winding it up. The film was stretched at a total stretching ratio of 5.3.

Relaxation heat treatment was performed at a relaxation rate of 7% to produce 450 denier monofilaments (46 pieces).

When spinning, a spinneret pack having the structure shown in Fig. 1 (the volume of the space inside the spinneret pack is 18
5cc) and preheated to a temperature of 260℃ and then heated to 50℃.
N-butylbenzenesulfonamide preheated to a temperature of C is sealed in the space 9 inside the spinneret pack.

Next, the spinneret pack was attached to the spinning device and spinning was started (Experiments 11hl to 9).

At this time, the amount of N-butylhenzensulfonamide enclosed and the release time of the spun fibers from immediately after the start of spinning until the start of winding were varied, and winding was started after the predetermined release time had passed. The number of yarn breakages that occur during the spinning process due to the inclusion of air bubbles during one use from the start of one winding to the elapse of 10 hours was investigated. Further, after a predetermined discharge time had elapsed, the state of contamination on the spinneret surface was observed and evaluated in three stages: first.

○: Almost no dirt △: There is some dirt, but cleaning of the cap surface is not necessary.

×: Cleaning of the cap surface is required.

The results are shown in Table 1.

As is clear from Table 1, in the experimental fish that satisfied the requirements of the present invention, after the release time had elapsed and winding was started, there were few yarn breakages due to air bubbles, and stable spinning was possible. In addition, the fiber can be stretched without causing yarn breakage in the stretching process.

The obtained monofilament was free from yarn mottling defects.

Example 2 The relative viscosity is 2.7 (using 96% concentrated sulfuric acid as the solvent).

Nylon 66 (N
66) was melted using an extruder-type melt-spinning device, and passed through a spinneret having 30 spinning holes with a circular cross section at a spinning temperature (nozzle temperature) of 280'C to give 510 g.
/min, taken in a cooling water bath at a temperature of 10°C to cool it, and then continuously passed through a hot water bath at a temperature of 90°C and a dry air bath at a temperature of 210"C without first winding it up. The total stretching ratio was set to 5.5.

Relaxation heat treatment was performed at a relaxation rate of 7% to produce 1000 denier monofilaments (30 filaments).

When spinning, a spinneret pack having the structure shown in FIG. 1 (the volume of the space inside the spinneret pack is 650
cc) and after preheating to a temperature of 290 °C.

Various substances were sealed in the space 9 inside the spinneret pack, and then the spinneret pack was attached to the spinning device and spinning was started (Experiments No. 10 to 12).

In addition, the amount of encapsulated substance was 5 g for each experimental floor.

The discharge time was kept constant at 10 m1n.

The results are shown in Table 1.

Experimental fish that satisfied the requirements of the present invention had fewer thread breakages.
Stable spinning was possible.

Table 1 (Effects of the Invention) According to the present invention, in a method for melt spinning a thermoplastic fiber-forming synthetic polymer, spinning can be stably continued after spinning is started. In addition, it is possible to produce fibers that have excellent process f1 transient properties in the subsequent process and are free from yarn unevenness defects.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a spinneret pack used in an example of the present invention. 1; Spinneret pack body, 2 needle cap. 4: Molten polymer introduction hole, 5: )! 9 materials 6: Breaker play 1-. 7: Spinneret 9: Space inside spinneret pack Patent applicant Unitika Co., Ltd.

Claims (1)

[Claims] (1) In melt spinning a thermoplastic fiber-forming synthetic polymer, a substance represented by the following general formula (A) and/or (B) is enclosed inside a spinneret pack heated to at least the spinning temperature, and then A melt spinning method characterized in that a spinneret pack in which the encapsulated substance is encapsulated is attached to a spinning device, a molten polymer is introduced, and spinning is started. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(A) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(B) [R is a saturated or unsaturated aliphatic hydrocarbon with 3 to 12 carbon atoms It is the basis. ]