JPH02210024A - Spinning method for conjugate fiber - Google Patents

Abstract

PURPOSE:To obtain conjugate fiber with good physical properties by melt spinning of a polyamide and polyester through setting their melt viscosity ratio at the spinning temperature within a specified range to effect favorable spinning and drawing process conditions. CONSTITUTION:(A) A polyamide, pref. nylon 6 or its copolymer and (B) a polyester with ethylene terephthalate residue accounting for pref. >=85mol% of constituent unit are put to melt spinning through setting the melt viscosity ratio at the spinning temperature pref. 270-295 deg.C so as to satisfy the relationship ([A] and [B] are each melt viscosity of the polyamide and polyester at the respective spinning temperatures), enabling drawing of the spun fiber under conditions suitable for both the polymers without causing any trouble, thus obtaining the objective conjugate fiber of good quality.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a composite fiber of polyamide and polyester. More specifically, the present invention relates to a method of separately melting polyamide and polyester and spinning core-sheath type composite fibers using one composite spinneret.

(Problem to be solved) When polyamide and polyester are melted separately and spun using a single composite spinneret, the thinning behavior of the yarn during spinning becomes unbalanced under conditions where the melt viscosities of both polymers are significantly different. Otherwise, single yarn breakage, screws falling off, knitting, and melt hook churning occur, resulting in poor spinning process performance. Even if a yarn is obtained on the temporary fabric, fluff and yarn breakage occur frequently in the drawing process 1ζ, making it impossible to draw the yarn sufficiently, resulting in poor quality yarn with low strength and elongation.

Generally, when a linear polymer such as polyamide or polyester is made into a fiber, it has sufficient strength and elongation (for example, the strength is 3.5
In order to obtain a yarn of good quality with f/d or higher and an elongation of 25 to 40%, it is necessary to draw the yarn at the optimal stretching rate for the spun yarn.

When polyamide and polyester are spun individually, they are spun at a spinning temperature that corresponds to the molecular weight of each polymer, and the spun yarn is drawn at a preferable drawing rate to produce a yarn with sufficient quality.

However, since composite fibers are made by spinning polymers with different properties in the same backing and drawing them under the same conditions, it is not always possible to obtain spinning/drawing conditions that are satisfactory for both, resulting in process problems (
(screws falling off, fuzz, yarn breakage, etc.) and quality deterioration often occur.

Conventionally, various methods have been proposed as solutions to this problem. For example, there is a method of using a complicated nozzle bag and setting the spinning temperature separately for each polymer. However, this method has disadvantages in that the nozzle back is a direct value and cleaning of the nozzle and parts is difficult.

The present invention aims to perform composite spinning under conditions that satisfy both polymers without using such complicated equipment, and to obtain composite core-sheath type fibers that have good processability and have fully satisfactory fiber properties.

(Means for Solving the Problems) The present inventors set the ratio of melting degrees of polyamide and polyester when performing composite spinning of polyamide and polyester as follows (1
) By selecting and combining the polymers and their conditions so that they fall within the range of the formula, the difference in melt viscosity between the two polymers and the difference in off-axis behavior under the spinneret are reduced, thereby making it possible to improve the performance in the spinning and drawing processes. It has been discovered that it is possible to improve the process condition and to take a value suitable for both the drawing ratios, and to produce a composite core-sheath yarn with good fiber properties.

2/1≦CB)/[A]≦4 ・・・・・・・・・
River... (1) Here, [A] is the melt viscosity of polyamide,
CB) Melt viscosity of polyester In the present invention, ``If the ratio of the melt viscosity of polyamide and polyester deviates from the formula (1), a significant difference will occur in the melt viscosity of both polymers, and melt fracture will occur partially. Poor stringability was caused by the low viscosity polymer. In addition, since the yarn cannot be wound under proper conditions, the spinning condition is poor and yarns are interrupted due to screws falling off. Even if it is possible to spin the temporary fiber, it may not be possible to obtain a stretching condition that satisfies both the drawing polymer and the drawing polymer, and the stretching may not be possible, or the stretching ratio that is optimal for one may be at a value that deviates from the optimal value for the other. Only fibers with poor yarn quality can be obtained.

However, within the range of the melt viscosity ratio of the present invention,
It is possible to obtain conditions that satisfy both polymers, and to obtain a good spun yarn with little difference in thinning behavior under the spinneret. Further, in the drawing process, it is possible to draw the film under suitable drawing conditions suitable for both polymers, and the processability is good and trouble-free, and a composite core-sheath fiber with good quality can be obtained.

The "polyamide" included in the present invention includes nylon-6, nylon-66, nylon-11, nylon-
12 or a copolymer thereof, among which nylon-6 is particularly preferred.

Examples of the "polyester" include polyethylene terephthalate, polyethylene terephthalate, polydimethylcyclohexanedimethanol and copolymers thereof, and those in which 85 mol% or more consists of ethylene terephthalate residues are particularly preferred.

When using a combination of nylon-6 as the polyamide and 85 mol% or more of polyethylene terephthalate (hereinafter abbreviated as PET) as the polyester, the melt spinning temperature is preferably 270°C or higher and 295°C or lower.

If it is less than 270℃, the appropriate spinning temperature for PET will be exceeded, and PE
The melt viscosity of T becomes too high, resulting in a tendency to melt hook char. If the temperature exceeds 295 DEG C., the temperature is too high for nylon-6 and it causes decomposition.] The viscosity becomes extremely low and the temperature is out of the optimum temperature range for thread formation, resulting in deterioration of processability and thread quality.

The "melt viscosity" referred to in the present invention is calculated by passing a certain amount of polymer through an orifice at a certain temperature, measuring the pressure loss at that time, and using the following formula.

4Q r=-i door Specifically, a predetermined nozzle was attached to the spinning head at the tip of the extruder, and the temperature, pressure, discharge amount, intrinsic viscosity, etc. were measured.

The intrinsic viscosity i was measured using an Utsuberohde viscometer using a 1/1 mixed solvent of phenol and tetrachloroethane at 30° C. in a conventional manner.

The following formula was used to convert the intrinsic viscosity [η] and the molecular weight (Mη).

Nylon-6 (Mη)==1.42X104[η]L8
! Polyethylene terephthalate log (Mη) = logcηILI gourd? +4.578
The term "composite fiber" used in the present invention refers to a core-sheath type composite fiber in which each single fiber in a filament yarn has various cross-sectional shapes as illustrated in FIG.

This will be explained below using examples.

Example-1 When nylon-6 with a molecular weight of 16,000 (intrinsic viscosity: 1.17) is used as the polyamide, the preferable spinning temperature is 260 to 275°C, and the melt viscosity is 2,000 to 1,500 voids at this temperature. .

Further, when a polymer having the molecule J118500 (intrinsic viscosity 0.60) in which 85 mol % or more is polyethylene terephthalate is used as the polyester, the preferable spinning temperature is 275 to 280°C. The melt viscosity at this time is 3000 to 2500 poise.

Both polymers were melted using separate extruders, and core-sheath yarns were spun using a single composite spinneret.

The spinneret was 0.25φX24H, the discharge amount was 35.891 minutes, and the yarn was wound at 322.5 dr at a winding speed of 1000 m/min.

(for 75 d/24 f after stretching), die temperature is 275°C
It was set to At this temperature, the melt viscosity of both polymers was 1,500 voices for nylon-6 and 3,000 voices for polyethylene terephthalate, which was twice the melt viscosity ratio.

The spinning condition was good, and there were no problems such as single yarn breakage, yarn breakage, or screws falling off.

When this spun yarn was stretched, the stretching ratio could be increased to 4.3 times, and a good quality with a strength elongation of 5.2 f//d to 30% could be obtained.

Example 2 Nylon-6 has the same molecular weight as in Example 1] 6000 (intrinsic viscosity 1.17). When a polymer having a molecular weight of 22,500 (intrinsic viscosity: 0.68) containing 85 mol% or more of polyethylene terephthalate is used as the polyester, the preferable spinning temperature is 290 to 300°C, and the melt viscosity is 3,500 to 3,000 voids.

Both polymers were melted using separate extruders, and a 75/24 core-sheath yarn was spun using a composite spinneret (0.25φ x 24H). The spinneret temperature was adjusted to the lower limit of the spinning temperature of this polyester, 290° C. (at lower temperatures, the spinning condition is poor and it is difficult to obtain a good yarn).

At this time, the melt viscosity of nylon-6 was 000 voids, and that of polyethylene terephthalate was 3,500 voids. The melt viscosity ratio of both polymers was 3.5 times.

The spinning condition was good, and there were no single yarn breakages or yarn breaks.

When the obtained yarn was stretched, the stretching ratio was 4.0 times, the strength was 4.5 f/d, and the elongation was 30%. The process was in good condition and there were no problems.

Comparative Example-1 Nylon-6 having the same molecular weight of 16,000 (intrinsic viscosity of 1.17) as in Example-1 is used. Polyester is polyethylene terephthalate with a molecular weight of 27,000 ([η]
= 0.78) and a 75/24 core-sheath yarn was similarly spun using a 0.3φ x 24H composite spinneret. The spinneret temperature was set at 298° C., the lower limit temperature at which polyethylene terephthalate can be spun.

At this time, the melt viscosities of nylon and polyethylene terephthalate were 800 voids and 6000 voids, respectively, and the melt viscosity ratio of both polymers was 7.5 times.

This yarn was in poor condition as wheel yarn breakage and yarn breakage occurred during spinning. When the obtained spun yarn was drawn, the drawing ratio was 3.0 times, and the strength and elongation of the drawn yarn was 2.2 f/d, 25%. It was the result.

This was because the spinning temperature was too high for the nylon, causing thermal decomposition of the nylon, and because the melt viscosities of the two polymers were significantly different, abnormalities such as 2-ing occurred, resulting in poor spinning performance. be.

Example-3 Nylon-6 molecular weight 210oo (intrinsic viscosity 1.38
) and the molecular weight of polyethylene terephthalate is 20,000
(Intrinsic viscosity: 0.64) Polymers were melt-extruded separately in the same manner as in Example 1, and spun at a spindle temperature of 283°C. Good spinning conditions were obtained.

At this time, the melt viscosity of nylon-6 is 1800 voices.
That of polyethylene terephthalate was 3300 voids, and the melt viscosity ratio of the two was 1.8 times.

When this was stretched at a stretching ratio of 4.2 times, the stretching condition was good.

The quality of the obtained yarn was satisfactory, with a strength of 5.3 f/d and an elongation of 36%.

Example-4 Nylon-6 has the same molecular weight as Example-3, 21,000
(intrinsic viscosity 1.38), and polyethylene terephthalate has a molecular weight of 22,500 (intrinsic viscosity 0.6).
The polymer of 8) was spun and stretched in the same manner as in Example 1. The spinneret temperature was 290°C.

The melt viscosity was 1300 poise for nylon-6 and 3500 poise for polyethylene terephthalate, giving a viscosity ratio of 2.7 times.

A 75/24 yarn was drawn at a drawing ratio of 4.0 times. As for processability, both spinning and stretching were good and there were no problems.

The quality of the drawn yarn was 4.8 fed to 32910, which was as expected.

[Brief explanation of the drawing]

FIG. 1 shows an example of the composite fiber of the present invention, and is a diagram illustrating various cross-sectional shapes. Patent applicant RiRa Shi Co., Ltd.

Claims (1)

[Claims] 1) When melt-spinning core-sheath composite fibers of polyamide and polyester, polyamide (A) and polyester (B
) Composite fiber spinning method characterized by setting the melt viscosity ratio at the spinning temperature to satisfy the range of formula (1) 1/2≦[B]/[A]≦4...・・・・・・・・・
(1) Here, [A] is polyamide, and [B] is the melt viscosity of polyester at the spinning temperature.2) Polyamide is nylon-6 or a copolymer thereof, and 85 mol% or more of the constituent units of polyester are ethylene terephthalate residues. A polyester composed of a polyester having a melt spinning temperature of 270°C or higher and 295°C
The method for spinning composite fibers according to claim 1, characterized in that: