Elastic polyurethane fiber and process for producing the same

Details Elastic polyurethane fiber and process for producing the same Elastic polyurethane fiber and process for producing the same

1999-08-12

2002-03-05

Acquah, Samuel A. (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

At least one aryl ring which is part of a fused or bridged...

C524S430000, C524S431000, C524S433000

Reexamination Certificate

active

06353049

ABSTRACT:

TECHNICAL FIELD
The present invention relates to an elastic polyurethane fiber, and a process for producing the same. The present invention relates, in more detail, to an elastic polyurethane fiber which hardly deteriorates in various chlorinated water environments and, particularly, which hardly deteriorates when used as swimwear in a swimming pool containing germicidal chlorine, and a process for stably producing the fiber.
BACKGROUND ART
An elastic polyurethane fiber obtained from an aromatic diisocyanate, a polyalkylene glycol and a polyfunctional hydrogen-containing compound has a high rubber elasticity, and is excellent in mechanical properties such as tensile stress and resilience, and thermal properties. Accordingly, the elastic polyurethane fiber as a stretchable functional fiber material has been widely used for applications requiring stretchability such as swimwear, foundation garments, stockings and sportswear.
However, when clothing products in which an elastic polyurethane fiber is used are repeatedly washed by immersing them in a chlorine bleaching agent over a long period of time, the elastic polyurethane fiber is known to lose its elastic function.
When swimwear in which an elastic polyurethane fiber is used is repeatedly exposed to a germicidal chlorine in water solution having an active chlorine concentration of from 0.5 to 3 ppm in, for example, a swimming pool, the elastic function thereof is significantly impaired or yarn breakage takes place during spinning. In particular, for swimwear comprising a polyamide fiber and an elastic polyurethane fiber, discoloration and fading of the fixed dye occur.
In order to improve the chlorine resistance of an elastic polyurethane fiber, a polyester-based elastic polyurethane fiber prepared by using an aliphatic polyester diol as a starting material has been employed. However, its chlorine resistance has been insufficient. Moreover, since an aliphatic polyester has a high biological activity, the polyester-based polyurethane has a disadvantage of being likely to be attacked by fungi. The polyester-based polyurethane therefore has the problem that the swimwear lowers its elastic function during its use or storage, and yarn breakage tends to take place. Although an elastic polyether-based polyurethane fiber prepared by using as a starting material a polyether diol having extremely low biological activity is not degraded by fungi, it has the problem that its chlorine resistance is still poorer than the polyester-based polyurethane.
Additives for improving deterioration of the elastic polyether-based polyurethane fiber caused by chlorine have been proposed. For example, Japanese Examined Patent Publication (Kokoku) No. 60-43444 discloses zinc oxide; Japanese Examined Patent Publication (Kokoku) No. 61-35283 discloses magnesium oxide, aluminium oxide, etc.; Japanese Unexamined Patent Publication (Kokai) No. 6-81215 discloses solid solution of magnesium oxide and zinc oxide.
The effects of magnesium oxide and aluminium oxide on the prevention of deterioration caused by chlorine which are disclosed in Japanese Examined Patent Publication (Kokoku) No. 61-35283 are not significant compared with comparative examples as shown in Table 1 on page 4 of the Patent Gazette. Zinc oxide disclosed in Japanese Examined Patent Publication (Kokoku) No. 60-43444 has the problem that the elastic polyether-based polyurethane fiber markedly lower its chlorine resistance because the zinc oxide component is eluted from the fiber during dyeing in an acid condition (pH 3 to 6) and the retained ZnO content in the fiber significantly decreases. The solid solution of magnesium oxide and zinc oxide disclosed in Japanese Unexamined Patent Publication (Kokai) No. 6-81215 produces little effect, similarly to zinc oxide. Although Japanese Unexamined Patent Publication (Kokai) No. 3-292364 discloses a polyurethane composition the chlorine resistance of which is improved by using hydrotalcite such as Mg
4.5
Al
2
(OH)
13
(CO
3
).3.5H
2
O, the improvement does not reach a satisfactory level.
For swimwear comprising an elastic polyurethane fiber and a polyamide fiber, in order to prevent discoloration and fading of dye used in the swimwear with chlorine contained in the water of a pool, the swimwear is subjected to dye-fixation treatment with a tannin solution after dyeing. When the elastic polyurethane fiber containing magnesium oxide or a solid solution of magnesium oxide and zinc oxide is subjected to dye-fixation treatment with a tannin solution (pH 3 to 4.5) after dyeing, these additives are eluted therefrom, whereby the chlorine resistance thereof is further lowered.
When these additives are added to a polyurethane spinning dope or a molten polyurethane during the production of an elastic polyurethane fiber, secondary agglomeration takes place, whereby clogging of the spinning filter or yarn breakage during spinning is increased. ZnO having a particle size of 0.1 to 1 &mgr;m is used in Japanese Examined Patent Publication (Kokoku) No. 60-43444; MgO having a particle size of 5 &mgr;m or less is used in Japanese Examined Patent Publication (Kokoku) No. 61-35283; solid solution of MgO and ZnO having a particle size of 0.05 to 3 &mgr;n is used in Japanese Unexamined Patent Publication (Kokai) No. 6-81215. Japanese Unexamined Patent Publication (Kokai) No. 3-292364 discloses a method for preventing secondary agglomeration by coating the surface of hydrotalcite (for example, Mg
4.5
Al
2
(OH)
13
(CO
3
).3.5H
2
O) with fatty acid. However, none of the inventions can achieve a satisfactory improvement.
An object of the present invention is to provide an elastic polyurethane fiber having excellent chlorine resistance over a long period of time after dyeing under an acidic dyeing condition (pH 3 to 6) or after dye-fixation treatment with a tannin solution (pH 3 to 4.5) subsequently to dyeing, and a process for stably producing the same.
DISCLOSURE OF THE INVENTION
As a result of intensively carrying out investigations to solve these problems, the present inventors have found that an elastic polyurethane fiber comprising, based on the polyurethane, 0.5 to 10% by weight of composite oxide particles which comprise bivalent metal M
2+
wherein M
2+
is at least one metal selected from the group consisting of zinc and magnesium, and aluminium, and in which the molecular ratio of the bivalent metal M
2+
to aluminium is from 1 to 5 not only has still more excellent chlorine resistance than the elastic polyurethane fiber to which the additives mentioned above are added, but also shows, astonishingly, that filter clogging and yarn breakage during spinning caused by secondary agglomeration of the composite oxide particles in the spinning dope are extremely reduced. They have therefore found that the elastic polyurethane fiber can be stably produced.
The composite oxide particles of the present invention can be produced by known methods. For example, the following methods are included therein: a method comprising melting a mixture containing zinc oxide, magnesium carbonate, aluminium hydroxide, etc. at 1,600° C., annealing the molten mixture at 600° C., and cooling the annealed material slowly (Journal of Non-Crystalline Solids, 129, 174-182 (1991); a method comprising firing a mixture containing zinc oxide and &ggr;-aluminium hydroxide at 900 to 1,000° C. (Journal of Japan Ceramic Society, 91 (6), 281-289 (1983)); a method comprising adding lithium chloride, ethyl silicate and hydrochloric acid to an aqueous solution of magnesium nitrate and aluminium oxide to effect reactions, and firing the reaction products at 700 to 1,300° C. (Chemistry Express, a (11), 885 to 888 (1990)); a method comprising spraying a solution of magnesium nitrate and aluminium nitrate in ethanol into a tube heated at temperatures from 740 to 1,030° C. to effect reactions (Ceramics International, 8, 17-21 (1982)). Composite oxides having various compositions and morphologies can be produced by suitably setting starting materials, a composition ratio of the starting materials, a reaction

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