JPS63270809A - Production of polyamide monofilament - Google Patents

Abstract

PURPOSE:To obtain the titled filament useful as tennis racket string and finishing line, having excellent knot strength, by carrying out heat drawing of polyamide monofilament in melt-spinning drawing spinning process with superheated stream at specific temperature at two stages and then heat-treating the monofilament. CONSTITUTION:Heat drawing of polyamide monofilament in melt-spinning drawing spinning process is carried out with superheated steam in a temperature range 40-90 deg.C lower than the melting point of polyamide resin at the first-stage drawing and then the monofilament is drawn simultaneously with superheated steam at the second-stage drawing in a temperature range 30-50 deg.C higher than that of the first-stage drawing. Then the monofilament is heat-treated to give the aimed monofilament. The heat treatment preferably is done by hot water or hot air in a temperature range of -10-+30 deg.C of the melting point of polyamide resin.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to the production of polyamide monofilament, which is used as a strong thread, especially a high-knot strong thread, for fishing lines, tennis racket strings, musical instrument strings, fishing net strings, etc. This relates to a manufacturing method.

(Prior art) Polyamide monofilaments have been manufactured for about 30 years by hot drawing after melt extrusion spinning.
Or a combination of these is used.

For example, if the first tank for stretching is A, the second tank is B, and the third tank is C, when passing through these tanks sequentially, the combinations of processing conditions shown in the following table are performed in each tank. ing.

In the above table, the wet method includes hot water and normal pressure steam, and there are also liquid phase methods using heated oil agents and organic solvents, and there are also methods using far infrared heating.

Polyamide is a material that has been developed because it has high heat retention properties and is suitable for clothing, but this means that it has physical properties such as poor heat conductivity, and monofilament with a large diameter is different from multifilament. In the early days, the stretching was carried out in a hot air tank because it was not possible to instantaneously stretch it using a hot plate as in the stretching of .

However, hot air has poor thermal efficiency with respect to polyamide monofilament, and there is a problem in particular in terms of knot strength. Later, a wet stretching method was developed, which improved the physical properties of the product compared to stretching with hot air.

(Problems to be Solved by the Invention) This wet method is more effective than hot air.
It is possible to improve the heat transfer efficiency by 0°C, and during stretching, it is possible to increase the micro-Brownian motion in the molecules at a temperature exceeding the glass transition point Tg, so that stretching can be performed easily and evenly. When the polyamide monofilament passes through the drawing water tank, the moisture or oil on its surface is immediately cooled by the heat of evaporation, resulting in moisture etc. adhering to the surface of the polyamide monofilament.

When the polyamide monofilament with moisture etc. attached to its surface is introduced into the next second stage drawing tank, when it is heated in the tank by wet or dry hot air, it is heated by the endothermic action of the water which has a large latent heat of vaporization. Not only does heating loss occur, but water and oil agents are randomly attached to the polyamide monofilament, resulting in large unevenness in the physical properties of the polyamide monofilament, making it impossible to obtain a polyamide monofilament with uniform strength. .

Furthermore, since polyamide is a resin that is easily oxidized, there is a problem in that when it is treated with hot air, it is rapidly oxidized and becomes brittle, resulting in a decrease in knot strength.

The present invention provides a method for producing polyamide monofilament aimed at solving these problems.

(Means for Solving the Problems) In order to achieve the above object, the method for producing a polyamide monofilament according to the present invention replaces the hot drawing in the melt drawing and spinning process of the polyamide monofilament with the polyamide resin during the first drawing by using superheated steam. 4 than the melting point of
After stretching at a temperature range of 0°C to 90°C lower than the first stage stretching, the second stage stretching was carried out using superheated steam at a temperature range of 30°C to 50°C lower than the first stage stretching.
It is characterized in that it is stretched in a temperature range 0°C higher and then heat treated.

(Function) Since the first-stage stretching and the second-stage stretching of the polyamide monofilament are performed under superheated steam, the entire polyamide monofilament is 2. It is heated quickly and uniformly to obtain a sufficient temperature during stretching, and the molecular motion of the polyamide resin is more active against the rapid stretching action than in other stretching methods such as dry hot air or wet stretching, and the molecular orientation is further improved. It is easy to draw, allows smooth stretching, and can increase knot strength by eliminating oxidation of the polyamide monofilament.

In addition, a higher temperature can be obtained due to the heat of condensation of the steam on the surface of the polyamide monofilament, and the thermal efficiency in the drawing tank is good, so there is no sudden temperature drop after passing through the tank, and heat dissipation due to heat of vaporization as in the conventional wet method etc. The conditions are favorable, contrary to the temperature drop.

(Example) A polyamide molten resin with a blending ratio of 87% nylon 6 and 13% nylon 66 was spun from the die of an extruder (1), then passed through a cooling tank (2) and a first drawing machine (3). , a first drawing tank (4), a second drawing machine (5), a second drawing tank (6), and a third tank (7) that performs heat treatment to produce a polyamide monofilament. Superheated steam at 140°C and 180°C is ejected into the tank (4) and the second drawing tank (6), respectively, and the spun polyamide monofilament is passed through the superheated steam (residence time: 1.5 to 5 seconds).
Then, in the first stretching tank (4), the stretching ratio was ×3°85,
After stretching at a stretching ratio of 1.5 in the second stretching tank (6), heat treatment (annealing) is performed in the third tank (7) using dry hot air at 230°C for a residence time of 2 to 6 seconds. A polyamide monofilament having a diameter of 0.285 mm and a denier of 655 was obtained.

On the other hand, as a comparative example, after spinning the above polyamide molten resin, it was subjected to wet treatment at a temperature of 99°C in the first tank and stretched at a stretching ratio of 3.8, and then at a temperature of 220°C in the second tank. A polyamide monofilament having the same diameter and the same denier as the above example was obtained by performing a dry hot air treatment and stretching at a draw ratio of 1°4, and then heat treatment (annealing) with dry hot air at 230°C in a third bath. I got it.

A comparison of the physical properties of the polyamide monofilament of the example of the present invention thus obtained and the polyamide monofilament of the conventional example is shown.

As is clear from the above table, the polyamide monofilament of the comparative example is a yarn belonging to the highest grade at present, but the example of the present invention has a linear break strength of about 24% and a knot break strength of about 24%, and a knot break strength of about 24%, even more than the comparative example. It was found that the physical properties were significantly improved by about 32%.

In the method of the present invention, a stable temperature of the superheated steam can be obtained by controlling the pressure. For example, if the pressure of the steam is 5 kg/
cd = 140'C, pressure of steam 10 kg/e
11! = 180°C, and is set within the above temperature range depending on the diameter of the polyamide monofilament to be produced, that is, within a temperature range of -40°C to -90°C below the melting point of the polyamide resin during the first stage stretching. During the second stage stretching, the temperature is set within a range of 30°C to 50°C higher than that during the first stage stretching.

On the other hand, when heat treatment (annealing) is performed with hot air, only the surface layer of the stretched polyamide monofilament is slightly melted by dry hot air with poor heat transfer, which disturbs the molecular orientation and forms a thin protective film on the surface. This condition alleviates surface friction during knotting and improves knotting strength, and the diameter does not increase compared to coating the surface of the polyamide monofilament with a resin solution.

Also, instead of heat treating the polyamide monofilament with hot air, it can be heated in hot water at 70 to 98°C for 3 to 2 hours after the second stage stretching.
A heat treatment in which the polyamide monofilament is passed for 0 seconds may be employed. According to this heat treatment, the polyamide monofilament is not oxidized unlike in dry hot air, and moreover, the molecular orientation can be made uniform.

Note that, as is customary, the surface of the obtained polyamide monofilament may be coated with a smoothing oil or a resin to protect the surface.

Next, the change in diameter during stretching of a polymer is calculated as: Diameter after stretching ÷ Diameter before stretching - 1
Formula, specific surface area after stretching + specific surface area before stretching = 4τb 1...0 formula, specific surface area 1 unit surface area (IIIlt12) 1,000 units volume (IIlf
i3)...The relationship of each equation equal to or greater than 0 holds true.

As shown in the above equation 0, the change in specific surface area before and after stretching is closely related to the stretching ratio. For example, if the stretching ratio is 5.5 times, the specific surface area after stretching/specific surface area before stretching-p=2.35.

In this way, in the hot drawing process where the specific surface area rapidly increases, applying a severe oxidation heat history causes deterioration of the polyamide monofilament being drawn, which inhibits the improvement of the fiber performance of the polyamide monofilament. It is.

Therefore, in the hot stretching process of polyamide resin, it is advantageous to use superheated steam instead of dry hot air, and to use superheated steam, which can obtain higher temperatures and has better thermal efficiency than the wet method.

(Effects of the Invention) As described above, according to the method for producing a polyamide monofilament according to the present invention, the first-stage stretching and second-stage stretching of the polyamide monofilament are performed using superheated steam, so that the entire polyamide monofilament is heated rapidly and uniformly. In addition to being able to obtain sufficient temperature necessary for stretching, the molecular motion of the polyamide resin is more active than in other stretching methods such as dry hot air or wet stretching, making it easier to orient the molecules. This method allows for smooth stretching and eliminates oxidation of the polyamide monofilament, thereby increasing knot strength.

In addition, a higher temperature can be obtained due to the heat of condensation of the steam on the surface of the polyamide monofilament, and the thermal efficiency in the drawing tank is good, so there is no sudden temperature drop after passing through the drawing tank, and the overall physical properties are uniform and good. Polyamide monofilament can be manufactured efficiently.

[Brief explanation of drawings]

The drawings are simplified process diagrams showing embodiments of the present invention. (1)...Extruder, (4)...First stretching tank, (6)
...Second stretching tank, (7)...Third tank. ,) Procedural amendment

Claims (2)

[Claims] (1) Hot drawing in the melt-drawing and spinning process of polyamide monofilament is carried out using superheated steam at a temperature range of 40°C to 90°C lower than the melting point of the polyamide resin during the first stage drawing, followed by the second stage drawing using superheated steam. A method for producing a polyamide monofilament, which comprises stretching at a temperature range of 30 to 50 degrees Celsius higher than the first stage stretching, and then heat-treating. (2) Heat treatment is carried out using hot water or -1 of the melting point of the polyamide resin.
2. The method for producing polyamide monofilament according to claim 1, wherein the manufacturing method is carried out using dry hot air at a temperature range of 0°C to +30°C.