JPH03809A - Production of extremely thin polyamide fiber - Google Patents

Abstract

PURPOSE:To obtain the title fiber having high breaking strength, high elongation at break and excellent handleability by carrying out spinning and drawing at high speed while maintaining atmospheric temperature below a spinneret at >= a specific temperature, heat-treating and winding. CONSTITUTION:Spinning and drawing are carried out at >=3,000m/minute while making atmospheric temperature at <=5cm below a spinneret at >=220 deg.C, preferably 240-300 deg.C, heat-treated at preferably 160-180 deg.C and wound to give the aimed fiber.

Description

[Detailed description of the invention] [Industrial use! P] The present invention relates to a method for producing ultrafine polyamide fibers, and more particularly to a method for producing ultrafine polyamide fibers that have high breaking strength and elongation at break that can withstand normal use and are easy to handle.

[Conventional technology]

A method for easily producing ultrafine fibers by improving the usual melt spinning method is disclosed in Japanese Patent Publication No. 35481/1981. However, the ultra-fine polyamide fiber obtained by this method has extremely low breaking strength and breaking elongation, and if you try to weave or knit it using normal methods, it will cause problems such as fuzz and thread breakage during the preparation process. Also, during weaving and knitting, there is a problem in that the machine frequently stops due to fuzz, etc.

The method disclosed in Japanese Patent Publication No. 62-35481 utilizes technology to draw a thread obtained by rapidly cooling it in a low-temperature atmosphere immediately after discharging a molten polymer from a discharge hole with a small cross-sectional area to make ultrafine fibers. It is interpreted that the above points are present. However, when polyamide is melt-spun and the atmosphere under the spinneret is cooled, it becomes a so-called weak yarn with low breaking strength and breaking elongation. As shown in Example 6 of the publication, only a strong elongation with a breaking strength of 3.4 g/denier and a breaking elongation of about 22% can be obtained.

(Problems to be Solved by the Invention) The present invention has a strength and elongation property comparable to that of commonly used polyamide multifilament, that is, a breaking strength of 4.5.
We produce ultra-fine polyamide fibers that have a g/denier or more, a breaking elongation of 40% or more, and can be handled on a par with conventionally commonly used polyamide multifilaments in processes including weaving and knitting preparation processes. The purpose is to provide a method for

[Means to solve the problem]

In the present invention, the temperature of the atmosphere up to 5 cm below the base is 220°C.
This is a method for producing ultrafine polyamide fibers, which is characterized in that the fibers are spun and taken off at a speed of 3,000 m/min or more while maintaining the above speed, followed by heat treatment and winding.

In the present invention, polyamide refers to nylon 6, nylon 6
．． 6, nylon 12 or copolymerized polyamide, etc.
Polyamide, which is usually melt-spun and used as synthetic fiber, may be mixed with other additives such as matting agents and heat stabilizers.

In the present invention, the spinning winding method is carried out by a normal melt spinning machine and is not special at all, but the diameter of the outlet hole is preferably as small as the machining accuracy allows, and the diameter of the outlet hole is preferably as small as possible, up to 5 cm below the spinneret. Ambient temperature 220℃
The quickest way to do this is to install an auxiliary chamber and heat it electrically.

If the ambient temperature up to 5 cm below the mouthpiece is less than 220° C., the discharged yarn is cooled and becomes brittle, making it impossible to obtain a yarn with high breaking strength and elongation. By setting this temperature to 220'C or more, preferably 240 to 300C, the discharged yarn can be given extensibility and a yarn with high breaking strength and elongation can be obtained.

If you take it off at a low speed in this condition, the yarn swing will be large, causing noticeable yarn unevenness and frequent single yarn breakage. Therefore, you must increase the take-off speed to 3,000 m/min or more, increase the spinning tension, and suppress the yarn swing. Polyamide fibers with a single filament fineness of 2 denier or more are spun at a speed of 3,000 to 4,000 m/min, and the residual elongation is too large to be used as is. When the single filament fineness becomes extremely fine with a fineness of 0.4 denier or less, the strength is high and the residual elongation is low, so that it can be put to practical use as it is without being drawn later. However, as it is, the winding strength becomes too high, making it impossible to form a package with a good rolled appearance. As a solution to this problem, the shrinkage rate of the fibers is reduced by heat treatment and the fibers are wound up. The heat treatment temperature at this time is appropriately determined by experiment, but is 160 to 18
The temperature is preferably in the range of 0°C, and the treatment is preferably carried out using a pair of Nelson rollers. In that case, the length of yarn contact with the roller surface is preferably in the range of 1 to 10 m, but the range is not limited to this, and treatment with steam is also preferred. But it goes without saying that it's a good thing.

In carrying out the present invention, as a means of reducing the spinning take-off tension, converging the yarn group by a guide at the point where the solidification of the discharged yarn is completed reduces air resistance,
Although it is effective in reducing the tension applied to the yarn group,
With this alone, it is not possible to reduce the spinning yarn take-off tension enough to obtain a package with a good winding appearance.

In the present invention, the fineness of the single filament of the ultra-fine polyamide fiber is not particularly critical, but it is preferably 0.3 denier or less, which gives the fiber a unique texture when knitted.

[Effect]

In the present invention, in order to produce ultrafine polyamide fibers with excellent strength and elongation characteristics, the atmosphere above the die is kept at a high temperature.
When the fineness of the single yarn is small, at normal spinning speed, if the ambient temperature above the spinneret is high, the yarn shaking of the discharged yarn will be large, which will not only cause noticeable yarn unevenness in the thinning process (this will induce yarn breakage. This problem In order to solve this problem, in the present invention, the spinning speed is increased as a means of increasing the tension of the yarn in the heated atmosphere under the spinneret and suppressing the yarn swinging.

However, if the spinning speed is increased, the spinning tension increases, so when the package is wound onto a bobbin, the tightening stress on the package increases, resulting in poor winding appearance. As a solution to this problem, the present invention further adopts a method of heat-treating the yarn after taking it off to relax the shrinkage rate of the yarn before winding it up (so that the breaking strength and breaking elongation are lower than those for normal use). The purpose is to obtain ultrafine polyamide fibers that are durable enough to withstand and have good handling properties.

[Example] Hereinafter, the present invention will be described in more detail with reference to Examples.

In the examples, breaking strength and elongation were measured as follows.

Breaking strength and elongation: Based on JIS L1013, Chemical Fiber Filament Yarn Test Method, Section 7.5.1, grip spacing 25c
te, was measured by pulling at a constant tensile speed of 30C11/min. The measuring device used was Autograph S-100 manufactured by Shimadzu Corporation.

Examples 1 to 3, Comparative Examples 1 to 2 A nylon 6 polymer having an intrinsic viscosity of 1.17 was spun and wound up using a conventional melt spinning device according to a conventional method. The cap used had a hole diameter of 0.06 mm and had 80 holes. An auxiliary chamber wrapped with a 15 cm electric band heater was attached directly below the cap. The ambient temperature was varied, and the temperature at a position 5 cm below the cap was measured.

A pair of Nelson rollers having a diameter of 18C11 and heated to 170° C. were attached to the take-up roller, and the spun yarn was wound five times, heat-treated, and then wound. Note that a thread group focusing guide was attached at a position 50 cm below the mouthpiece to focus the thread group, and at the same time, an oil agent was applied.

Ultrafine fibers were obtained by spinning and winding with various polymer discharge amounts and spinning speeds, and the breaking strength and breaking elongation were measured, and the number of yarn breakages in tube knitting was investigated. The knitting was performed at a knitting speed of 110 rn/min with 360 stitches.

The results obtained are shown in Table 1, and the fibers according to the present invention have high breaking strength and elongation, have a small number of yarn breakages during spinning, and have ? The number of yarn breaks in terms of J'IiM was also small, indicating ease of handling.

(Margins below) (Effects of the invention) According to the method of the present invention, ultrafine polyamide fibers that could not be obtained without significantly lowering the breaking strength and elongation can be obtained without any trouble even when using the normal wi knitting process. Since it can be obtained in a state with improved breaking strength and elongation so as not to cause the occurrence of oxidation, and is easy to handle, it is particularly useful when used as a continuous filament in a material.

The ultrafine polyamide fibers obtained by the present invention may be used as they are in woven or knitted fabrics, but they can also be false-twisted, wrapped around elastic yarns, or interlaced with other fibers to create a unique texture. We can provide threads with

Patent applicant: Teijin Ltd. Agent: Patent Attorney Takashi Shirai

Claims (1)

[Claims] (1) The temperature of the atmosphere up to 5 cm below the surface of the spinneret is 220°C.
A method for producing ultrafine polyamide fibers, which comprises spinning the fibers at a speed of 3,000 m/min or higher while maintaining the temperature at ℃ or higher, followed by heat treatment and winding.