JP2002155421A - Method for dry spinning - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase productivity in a dry spinning without impairing fiber properties and causing instability such as yarn shaking, joined yarn. SOLUTION: This method for dry spinning is characterized in that, in facilities adopting a nozzle of high-speed spinning multiple end, the amount of a dry gas introduced to a spinning chimney per unit time is made a specific value or above corresponding to the amount of a polymer solution discharged to the spinning chimney per unit time and a temperature at the wall face of the spinning chimney and a temperature of a dry gas in the spinning chimney satisfy a specific relational expression.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry spinning method in which a spinning solution composed of a solvent, a polymer and various additives is extruded from a nozzle into a spinning cylinder, and the solvent is dried by a heated gas to form a yarn. . More particularly, the present invention relates to a dry spinning method characterized by realizing high productivity without deteriorating yarn physical properties, and obtaining an elastic yarn with small yarn unevenness by rectifying a heated gas in a spinning cylinder.

[0002]

2. Description of the Related Art As a typical fiber material produced by a dry spinning method, there is a polyurethane elastic yarn. Regarding the method for producing the polyurethane elastic yarn, there is generally a means for increasing the spinning speed as a means for improving the productivity.

However, if the spinning speed is simply increased, the drying in the spinning cylinder becomes insufficient, the physical properties of the yarn are remarkably reduced, and unstable phenomena such as yarn swaying occur. At present it was not possible to obtain quality products. Furthermore, the polyurethane elastic yarn thus obtained had a low elongation at break and a high modulus.

[0004] To solve these problems, it has been proposed to add a sulfonate to the spinning dope as an improvement measure from the spinning dope (Japanese Patent No. 2968049). However, if a salt is added to the spinning dope, it is not preferable because there is a possibility of contamination in the cylinder due to precipitation of the salt in the spinning step, a change in the distillation step of the recovered solvent, and an adverse effect in the post-processing step.

As improvements in the spinning process, a method of discharging a spinning solution at a temperature of 80 ° C. or higher (Japanese Patent Application Laid-Open No. 10-77323), a method of heating the temperature of a spinning cylinder and a method of introducing a high-temperature gas from the bottom of the spinning cylinder.
(JP-A-5-51808) has been proposed.

However, when the spinning solution is heated to 80 ° C. or higher, the polymer component of the spinning solution tends to gel, so that
Since the clogging of the spinning filter is remarkable and the pressure loss increases as a result, the filter replacement cycle is shortened, and problems such as frequent breakage of the yarn occur.

If means for heating the temperature of the spinning cylinder or introducing high-temperature gas from the lowermost part of the spinning cylinder is adopted, an upward flow is generated in the spinning cylinder, so that the airflow in the cylinder is disturbed, and yarn spots become large. In addition, it is easy to come into contact with the yarn from another nozzle arranged in the same cylinder, so that unstable phenomena such as a cause of yarn breakage and a double yarn between a plurality of nozzles frequently occur, which is not preferable.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a dry spinning method which realizes high productivity without impairing the yarn properties and disturbing the air flow in the spinning cylinder.

[0009]

That is, the present invention is characterized by satisfying the following formulas (1) and (2) in a dry spinning method represented by a method for producing a polyurethane elastic yarn. [(q × α / Ms) × Ls] / (Cp × Q) ≦ 40 Equation (1) Each symbol in the equation indicates the following content. q: Amount of spinning dope discharged into the spinning cylinder per unit time [g / s] α: Solvent weight fraction in spinning dope [-] Ms: Solvent molecular weight [g / mol] Ls: At heated gas blowing temperature Latent heat of solvent evaporation [cal / mol] Cp: Specific heat of heated gas at blowing temperature [cal / mol / ° C] Q: Amount of heated gas sent into spinning cylinder per unit time [mol / s] Tgas ≧ 0.04 × Vw + 210 Equation (2) Each symbol in the equation indicates the following. Tgas: heated gas blowing temperature [° C.] Vw: spinning speed [m / min] Further, the present invention provides a dry spinning method as described above wherein the spinning tube heating is adjusted so as to satisfy the condition of the following formula (3). is there. Tw ≦ T _gas −ΔT Equation (3) Each symbol in the equation indicates the following. ΔT = [(q × α / Ms) × Ls] / (Cp × Q) [° C] Tw: Temperature of the spinning cylinder wall surface [° C] T _gas : Temperature of heated gas blowing [° C]

The inventors of the present invention have intensively studied, in a dry spinning method typified by a method for producing a polyurethane elastic yarn, a measure for suppressing a decrease in yarn physical properties when spinning at a high speed. As a result, the higher the spinning speed, the higher the spinning. The present inventors have found that it is necessary to increase the cylinder temperature, particularly the temperature at the lower part of the spinning cylinder, and have reached the present invention.

Hereinafter, taking polyurethane elastic yarn as an example,
Although the details of the present invention will be described, other materials adopting the dry spinning method can be similarly applied.

When the spinning speed is increased in the dry spinning of polyurethane elastic yarn, the amount of the spinning dope discharged into the spinning cylinder increases in order to obtain an elastic yarn of the same fineness, and therefore the amount of solvent per unit time also increases. growing. Furthermore, since the amount of latent heat of evaporation required for evaporating the solvent contained in the spinning solution increases, the temperature in the spinning cylinder decreases.

As a means for raising the temperature of the spinning cylinder for the purpose of improving the above-mentioned problems, if the spinning cylinder is excessively heated, an upward flow is generated in the cylinder, the air flow in the spinning cylinder is largely disturbed, and the yarn spots become large. It becomes easy to come in contact with the yarn from another nozzle arranged in the cylinder, and unstable phenomena such as yarn breakage and tying between a plurality of nozzles frequently occur.

The present invention relates to a dry spinning method for obtaining a high lower temperature of a spinning cylinder without generating an upward flow in the spinning cylinder. That is, with high-speed spinning or increasing the number of nozzles arranged in the same cylinder (multiple end), the equations (1) and (2) are used.
This is achieved by controlling the amount and temperature of the dry gas blown into the spinning cylinder within a range satisfying the above condition. Equation (1)
By setting the temperature within the range shown in the figure, it is possible to prevent the temperature in the spinning cylinder from lowering due to the latent heat of solvent evaporation, and to set the heated gas blowing temperature to the equation (2).
It is important to set within the range indicated by.

When the ranges of the formulas (1) and (2) are not satisfied, the drying of the solvent is insufficient and the elasticity of the obtained elastic yarn is undesirably small.

Further, by maintaining the temperature in the spinning cylinder within the range represented by the formula (3), the structure is developed from the drying of the spinning stock solution in the entire area from the upper part to the lower part of the spinning cylinder without the occurrence of upward flow. The required amount of heat can be secured.

When an ascending flow is generated, the airflow in the spinning cylinder is greatly disturbed, and the yarn spots become large, making it easier to come in contact with the yarn from another nozzle arranged in the same cylinder, causing a yarn breakage or a merge between a plurality of nozzles. Although unstable phenomena such as yarn frequently occur, it is preferable to satisfy Expression (3) from the viewpoint of preventing the occurrence of the upward flow.

[0018]

As described above, the present invention is an epoch-making method capable of realizing high productivity by high-speed spinning and multi-end in the dry spinning method. The present invention will be specifically described below. The invention is not limited to these examples.

(Measurement method of elongation and modulus of elastic yarn)
Using a Tensilon tensile tester (manufactured by Orientec Co., Ltd.), the sample is gripped at chuck intervals of 50 mm,
The sample is stretched at a speed of 500 mm per minute, and the stress at break (dry strength), elongation (dry elongation, described as elongation at break in Table 1), and stress at 300% elongation (described as SS300 in Table 1) Was measured. The measurement atmosphere was a temperature of 20 ° C and a humidity of 65.
It has been adjusted to%.

(Method of Observing Yarn Sway) An observation window was set at a position of 200 cm and 300 cm from the nozzle surface of the spinning cylinder, and the oscillation of the elastic yarn generated by the drying wind was observed.
Those having a size of 5 cm or more were evaluated as x, those in the range of 3 to 5 cm were evaluated as Δ, and those less than 3 cm were evaluated as ○.

(Example 1) 200 parts of polyoxytetramethylene glycol having a molecular weight of 1800 and 45 parts of methylene-bis (4-phenylisocyanate) were reacted at 80 ° C for 3 hours to obtain an intermediate polymer having isocyanate groups at both terminals. Was. Intermediate polymer
After cooling to 40 ° C., 375 parts of N, N-dimethylacetamide was added to dissolve the intermediate polymer and cooled to 10 ° C. A solution prepared by dissolving 4.0 parts of ethylenediamine and 0.4 part of diethylamine in 147.6 parts of N, N-dimethylacetamide was added at a stretch to the place where the intermediate polymer solution was rapidly stirred to obtain a polyurethane solution. . Add various stabilizers, viscosity 2500 poise, polymer concentration 30.0 weight
% Polyurethane solution was obtained. The dimethylacetamide solution of the polyurethane polymer thus obtained was discharged into a spinning cylinder provided with 16 nozzles each having a 2-hole spinning hole, and a yarn having a spinning speed of 1000 m / min and 22 dtex was obtained. At this time, 260 ° C. N ₂ gas was used as the heating gas.
Blowing was performed to the spinning cylinder at a speed of 0 Nm ³ / min, and the heat retention heater was set so that the wall temperature of the spinning cylinder was 220 ° C. Table 1 shows the spinning results. Table 2 shows spinning conditions and the like.
3 is shown.

(Example 2) Spinning was performed in the same manner as in Example 1 except that the number of spinning nozzles was 24 and the flow rate of the heated gas was 4.0 Nm ³ / min. The spinning results are shown in Table 1. Tables 2 and 3 show spinning conditions and the like.

Comparative Example 1 Spinning was carried out in the same manner as in Example 1 except that the flow rate of the heated gas blown into the spinning cylinder was 0.7 Nm ³ / min. The spinning results are shown in Table 1. Tables 2 and 3 show spinning conditions and the like.

(Comparative Example 2) The heating gas blowing temperature was 210 ° C.
The spinning was carried out in the same manner as in Example 1 except that the wall temperature of the spinning cylinder was set to 150 ° C. Table 1 shows the spinning results.
Shown in Tables 2 and 3 show spinning conditions and the like.

Comparative Example 3 The number of spinning nozzles was 24, the temperature of the heated gas was 210 ° C., and the wall temperature of the spinning cylinder was 260
Spinning was performed in the same manner as in Example 1 except that the temperature was changed to ° C.
Table 1 shows the spinning results. Table 1 shows the spinning results. In addition,
Tables 2 and 3 show spinning conditions and the like.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

According to the dry spinning method of the present invention, productivity can be improved without impairing yarn physical properties and without causing instability such as yarn swaying and twining in equipment employing a high-speed spinning multi-end nozzle. It became possible to increase.

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Claims (2)

[Claims] 1. A dry spinning method for extruding a spinning stock solution from a nozzle into a spinning cylinder and evaporating a solvent by a heated gas to form a yarn, wherein the following formulas (1) and (2) are satisfied. A dry spinning method, characterized in that: [(q × α / Ms) × Ls] / (Cp × Q) ≦ 40 Equation (1) Each symbol in the equation indicates the following content. q: Amount of spinning dope discharged into the spinning cylinder per unit time [g / s] α: Weight fraction in spinning dope [-] Ms: Solvent molecular weight [g / mol] Ls: Solvent at heated gas blowing temperature Latent heat of vaporization [cal / mol] Cp: Specific heat of heated gas at blowing temperature [cal / mol / ° C] Q: Amount of heated gas sent into spinning cylinder per unit time [mol / s] Tgas ≧ 0.04 × Vw + 210 (2) Each symbol in the formula indicates the following. Tgas: Heated gas blowing temperature [° C] Vw: Spinning speed [m / min] 2. The dry spinning method according to claim 1, wherein the heating of the spinning cylinder is adjusted so as to satisfy the following expression (3). Tw ≦ T _gas −ΔT Equation (3) Each symbol in the equation indicates the following. ΔT = [(q × α / Ms) × Ls] / (Cp × Q) [° C] Tw: Temperature of the spinning cylinder wall surface [° C] T _gas : Temperature of heated gas blowing [° C]