JPH07189119A - Water-absorbing polyamide fiber and its production - Google Patents

Abstract

PURPOSE:To obtain a new polyamide fiber having light weight and excellent water-absorbing performance, water-retaining performance and water-releasing performance and free from slimy feeling. CONSTITUTION:This polyamide fiber is characterized in that the single fiber constituting the polyamide fiber is a dense agglomerate of fibrils oriented nearly parallel to the fiber axis. It can be produced by subjecting a fiber obtained by the melt-spinning of a blend polymer composed of 70-50wt.% of a polyamide and 30-50wt.% of a polyester obtained by the copolymerization of a polyethylene terephthalate with 10-30wt.% of a polyethylene glycol, thereby dissolving and removing the copolymerized polyester.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for clothes such as sports and materials for water absorbent rugs, does not have a slimy feeling peculiar to polyamide fibers, is lightweight, and has water absorption performance, water retention performance, and The present invention relates to a novel polyamide fiber having excellent water discharge performance and a method for producing the same.

[0002]

2. Description of the Related Art As a method for removing the slimy feeling peculiar to polyamide fibers, 1 to 10% by weight of polyester is uniformly mixed and melted with polyamide, and the mixed fibers obtained by spinning and drawing are mixed with alkali metal hydroxide. To elute 50 to 100% by weight of the polyester in the yarn,
A method has been proposed in which fine streaky irregularities are formed on the surface of a fiber (Japanese Patent Publication No. 45-1646).

[0003] Since this method has a very poor productivity due to frequent breakage of fibers during spinning and fluff breakage during stretching, the fiber obtained by mixing and spinning a polyester containing an organic sulfonic acid metal salt and a polyamide is A method of eluting and removing polyester has been proposed (JP-A-2-175965).

[0004]

However, since the fibers obtained by the above-mentioned prior art only have streak-shaped fine pores in the length direction, the texture of the fibers is silk-like,
The water absorption performance, water retention performance, and water discharge performance could not exceed cotton. TECHNICAL FIELD The present invention relates to a novel polyamide fiber which does not have a slimy feeling peculiar to polyamide-based fibers, is lightweight, and is excellent in water absorption performance, water retention performance, and water discharge performance, and a method for producing the same.

[0005]

Means for Solving the Problems As a result of intensive research for solving the above problems, the present inventors have found that a fiber structure different from the fiber structure having streak-shaped fine pores obtained by the prior art is used. The present invention has been found to be able to solve all the above-mentioned problems, and the present invention has been achieved. The present invention comprises monofilaments constituting polyamide fibers, which are composed of a tight aggregate of fibrils arranged substantially parallel to the fiber axis direction. Obtained by melt spinning a polyamide fiber, and a blend polymer of 70 to 50% by weight of polyamide and 30 to 50% by weight of polyester obtained by copolymerizing polyethylene terephthalate with 10 to 30% by weight of polyethylene glycol. Production of polyamide fiber, characterized in that the copolyester is eluted and removed by subjecting the treated fiber to alkali reduction treatment Law, it is.

Polyamides used in the present invention include nylon 6, nylon 66, nylon 610, nylon 4
Aliphatic polyamides such as 6 and nylon 12 are preferred. Further, these polyamides may be those obtained by copolymerizing an aromatic component such as terephthalic acid and isophthalic acid, but nylon 6 and nylon 66 are preferable. In addition,
If necessary, the polyamide may contain any additive such as an antistatic agent, an anti-coloring agent, a flame retardant, a matting agent, and a coloring agent.

On the other hand, the copolyester used in the present invention needs to have better compatibility with polyamide than polyethylene terephthalate, which is often used in the conventional known techniques, and can be finely mixed with polyamide. is necessary. For that purpose, it is desirable to use terephthalic acid as a main acid component and polyethylene glycol as a main glycol component in addition to ethylene glycol. In this case, the added weight of polyethylene glycol at the time of polymerization is preferably 10 to 30% by weight. If the weight of polyethylene glycol is less than 10% by weight, it becomes difficult to finely mix it, and if it exceeds 30% by weight, the heat resistance of the copolyester becomes poor, and the spinnability and drawability deteriorate, resulting in yarn breakage. Frequently occurs.

The problem of the present invention can be better solved by not using the organic sulfonic acid metal salt-containing polyester, and if it is used, it should be limited to 5% by weight or less. Fine fibrils can be formed when the copolyester which is a constituent of the present invention is used, but when other copolyester or polyethylene terephthalate is used, for example, JP-A-2-175965. Forming streak-like holes as shown in the drawings described, because it has a different fiber surface structure from the present invention, does not have the slimy feeling peculiar to polyamide fibers, is lightweight, and also has water absorption performance and water retention performance. However, it is not possible to obtain polyamide fibers having excellent water discharge performance.

The desirable mixing ratio of polyamide and copolyester varies depending on the degree of polymerization of each polymer and the spinning temperature, but is 70 to 50% by weight of polyamide.
Copolymerized polyester is preferably 30 to 50% by weight. When the mixing ratio of polyamide exceeds 70% by weight, it becomes difficult to form fine fibrils, the change of the fiber surface is small, and only pearl luster is exhibited as is known in the blended fiber with polyethylene terephthalate. . On the other hand, if the mixing ratio of the polyamide is less than 50% by weight, the produced fibrils will be dispersed in the weight reduction treatment liquid, and the fiber form will not be retained.

When the fiber of the present invention is spun, the polyamide polymer and the copolyester polymer may be used as a chip blend in advance. The spinning pack and spinneret used for spinning may be conventional ones. The spinning and stretching steps may be continuous, or may be once wound into a package and then stretched. Then, if necessary, false twisting is performed, and then a structure such as a knitted fabric or a woven fabric is formed.
The copolyester can be easily removed from the fibers by the immersion treatment with an alkaline solution.

The alkaline solution used here is preferably an aqueous solution of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, tetramethylammonium hydrosulfite, or a mixture thereof. , Potassium hydroxide is particularly preferable. It is also preferable to use a weight loss promoter. The concentration of the alkaline compound in the alkaline solution varies depending on the type of the alkaline compound and the treatment conditions, but is usually 0.01.
The range is from -40% by weight, and the range is preferably from 0.1 to 30% by weight.

The treatment temperature is usually from room temperature to 100 ° C., and the treatment time is usually from 1 minute to 4 hours, preferably 1
Minutes to 60 minutes is more preferable. The amount of the copolyester to be eluted and removed by the treatment with the alkaline solution is at least 50% by weight of the content of the copolyester.
Is preferred. In this case, it is more preferable to remove 90% by weight or more.

As shown in FIGS. 1 and 2 (all electron micrographs) of the polyamide fiber thus obtained, the single fibers constituting the polyamide fiber are arranged approximately parallel to the fiber axis direction. It is composed of tightly packed aggregates of fibrils of a few μm or less. The change in outer diameter of the single fiber before and after the alkali weight reduction treatment is almost within the error range. Such a structure has not hitherto been known. The use of the fiber having the structure of the present invention makes it possible to obtain a polyamide fiber that does not have a slimy feeling peculiar to polyamide-based fibers, is lightweight, and is excellent in water absorption performance, water retention performance, and water discharge performance.

[0014]

EXAMPLES The present invention will be described more concretely with reference to the following examples. Water absorption height by the Bayrec method: A load of 0.1 g / d was applied to the sample, and a part of the sample was immersed in water at 20 ° C for 10 minutes, and then the height of the water column sucked up Moisture content: Absolute dry sample weight Percentage of water absorption relative to 1 G water retention rate: After the sample is immersed in water for 20 minutes, it is taken out from the water. Moisture content of the fabric after gripping one end with a clip and hanging it for 5 minutes. 154G water retention rate: 840 rpm household washing machine dehydrator (corresponding to 154 times the acceleration of gravity) for 30 seconds after dehydration of the sample 1782 G water retention rate: 3500 rpm Centr type centrifugal dehydrator (gravitational acceleration of 1782) Moisture content of the sample after dehydration for 5 minutes after the rotation stabilizes. Centrifuge centrifugal dehydrator with a water discharge rate of 3500 rpm (equivalent to 1782 times the acceleration of gravity) for 5 minutes after the rotation stabilizes. It is the average reduction rate of water content in 10 minutes when the dehydrated fabric is left to dry in a room at 20 ° C. and 65 RH for 10 minutes.

[0015]

EXAMPLE 1 Nylon 66 having a melt viscosity of 400 poise at 280 ° C., 51 parts of dimethyl terephthalate, 26 parts of polyethylene glycol having a molecular weight of 6000, and 23 parts of ethylene glycol were polymerized to obtain a melt viscosity of 4 at 280 ° C.
Nylon 6 with 00 poise of copolyester
The mixing ratio of 6 and the copolyester is 60:40 by weight.
As a chip blend, the fiber was spun and then stretched to obtain a fiber of 293 denier / 48 filament.

This fiber was used as a one-piece knitted fabric and immersed in a 5% by weight sodium hydroxide aqueous solution at 90 ° C. for 10 minutes to elute and remove the copolymerized polyester almost completely. The apparent weight loss rate was 39% by weight. When the surface of this knitted fabric was observed with a scanning electron microscope at a magnification of 2000 times, the side face of the single fiber had a close aggregate structure of fibrils in which fine fibrils of 2 μm or less were arranged in parallel in the fiber axis direction. (Figure 1). The cross section of the monofilament cut with a knife showed a tightly assembled structure of fibrils inside the monofilament (Fig. 2). The knitted fabric did not have the slimy feeling peculiar to polyamide-based fibers, was lightweight, and had a dry-touch feel.

When the diameter of the monofilament cut with a knife was measured, it was 28.3 μm before the alkali weight reduction treatment and 28.6 μm after the alkali weight reduction treatment, and there was no difference within the error range. Assuming that the specific gravity of nylon 66 is 1.14, the apparent specific gravity of the fiber of this example after the alkali reduction treatment is 0.7.
It was 0. When this knitted fabric was immersed in warm water of 40 ° C., it floated above the water surface while generating bubbles, and eventually sank below. Therefore, it was estimated that the fibril-like voids were continuous to some extent.

Further, the water absorption height of the fibers unwound from the knitted fabric is 74 mm, the 1G water retention rate of the knitted fabric is 240%,
154G water retention rate is 135%, 1782G water retention rate is 68%
%, And the water discharge rate was 1.5% / min, which were both large. That is, it had a high water absorption property, a high water retention property and a high speed drying property. By the way, the water absorption height of the Bayrek method of cotton fiber is 43 mm, the 1G water retention rate of the knitted fabric is 189%, the 154G water retention rate is 109%, 1
The 782G water retention rate was 44%, and the water discharge rate was 1.1% / min.

[0019]

Example 2 Nylon 66 having a melt viscosity of 400 poise at 280 ° C., 59 parts of dimethyl terephthalate, 15 parts of polyethylene glycol having a molecular weight of 6000 and 26 parts of ethylene glycol were polymerized to obtain a melt viscosity of 4 at 280 ° C.
Nylon 6 with 00 poise of copolyester
The mixing ratio of 6 and the copolyester is 65:35 by weight.
As a chip blend, it was spun and then stretched to obtain 290 denier / 48 filament fibers.

This fiber was used as a one-piece knitted fabric and was immersed in a 5% by weight aqueous solution of sodium hydroxide at 90 ° C. for 30 minutes to elute and remove the copolymerized polyester almost completely. The apparent weight loss rate was 33% by weight. When the surface of this knitted fabric was observed with a scanning electron microscope at a magnification of 2000 times, the side face of the single fiber had a close aggregate structure of fibrils in which fine fibrils of 2 μm or less were arranged in parallel in the fiber axis direction. . The cross section of the monofilament cut with a knife showed a tightly assembled structure of fibrils inside the monofilament. The knitted fabric did not have the slimy feeling peculiar to polyamide-based fibers, was lightweight, and had a dry-touch feel.

The water absorption height of the fibers unwound from the knitted fabric was 72 mm, and the 1G water retention rate of the knitted fabric was 232%, 154.
The G water retention rate was 131%, the 1782G water retention rate was 62%, and the water discharge rate was 1.6% / min. That is, it had a high water absorption property, a high water retention property and a high speed drying property.

[0022]

Comparative Example 1 As a sheath component, the melt viscosity at 280 ° C. is 40.
Spinning and drawing were performed in the same manner as in Example 1 except that 0 poise of polyethylene terephthalate was used, but yarn breakage occurred frequently and sampling was impossible.

[0023]

Comparative Example 2 Nylon 66 having a melt viscosity of 400 poise at 280 ° C. was melt-spun and drawn using a spinneret having an L-shaped discharge hole to obtain a fiber of 60d / 48f. After the fiber was formed into a single knit, the unwound fiber had a small water absorption height of 29 mm, which was inferior to that of cotton. The 1G water retention rate of the knitted fabric is 304%, 154G
The water retention rate was 209%, which was superior to that of cotton.
The water retention rate of 82G was 14%, which was inferior to cotton.

[0024]

As described above, according to the present invention,
It is possible to obtain a novel polyamide fiber that does not have a slimy feeling peculiar to polyamide-based fibers, is lightweight, and has excellent water absorption performance, water retention performance, and water discharge performance.

[Brief description of drawings]

FIG. 1 is an electron micrograph (x2,000) showing an example of a surface state of a side surface of a water-absorbent polyamide fiber of the present invention.

FIG. 2 is an electron micrograph (x2,000) showing an example of a surface state of a cross section of the water-absorbent polyamide fiber of the present invention.

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[Procedure amendment]

[Submission date] December 27, 1993

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[Document name to be corrected] Drawing

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Claims (2)

[Claims] 1. A polyamide fiber characterized in that the single fiber constituting the polyamide fiber is constituted by a tight aggregate of fibrils arranged substantially parallel to the fiber axis direction. 2. Polyamide 70 to 50% by weight, polyethylene terephthalate and polyethylene glycol 10
-30% by weight Copolymerized polyester 30-50% by weight
A method for producing a polyamide fiber, which comprises subjecting a fiber obtained by melt-spinning a blended polymer of (1) to (3) to alkali reduction treatment to elute and remove the copolyester.