Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2001-09-18
2002-10-22
Edwards, Newton (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S394000, C264S205000
Reexamination Certificate
active
06468652
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a polyurethane-urea elastic fiber excellent in thermosettability and dyeability. Further, it relates to a method for producing a polyurethane-urea elastic fiber having a good elastic function as well as providing a favorable spinning stability.
BACKGROUND ART
A polyurethane-urea elastic fiber is known which is obtained by chain extending an isocyanate-terminated prepolymer synthesized by reacting polyalkylene ether glycol with organic diisocyanate in excess quantity by diamine. The polyurethane-urea elastic fiber has been used as a stretchable functional material while being mixedly knit or woven with polyamide fiber and/or polyester fiber for various fields of clothing, such as foundation garment, socks, panty hose, swim suits, sports wear, leotards or others.
The polyurethane-urea elastic fiber forms strong physical crosslinking of hydrogen bonds, caused by hard segments composed of an urea group, and exhibits an excellent elastic function. However, when the polyurethane-urea elastic fiber is used for fields wherein a shape-retaining property of a product fabric is particularly required; for example, a circular knit fabric field including leg wear such as panty hose or tights, a warp knit fabric filed including underwear and sports wear such as brassieres, girdles or swim suits, or a woven fabric field including outer wear such as bottom suit; processing an intermediate product thereof is problematic in that, because the polyurethane-urea elastic fiber is poor in thermosettability, an intermediate product could not be finished into a predetermined size thereby resulting in formation of a finished product inconvenient for wearing, or a hem of the fabric is liable to curl up to disturb the sewing operation.
Also, when the product is set to have a predetermined width, it is necessary to repeat the setting operation or setting at a relatively high temperature for obtaining a desired result, which deteriorates the productivity and the heat efficiency.
Other elastic fibers having no urea groups but similar to the polyurethane-urea elastic fiber, such as polyurethane elastic fiber (elastic fiber solely composed of urethane bonds) or polyether-ester elastic fiber (polyester copolymerized with polyalkyleneether glycol component), are also known. While these elastic fibers are excellent in thermosettability and shape-retaining property, they have no hard segments composed of urea groups, and therefor are problematic in that the elastic function is liable to be damaged; i.e., the elastic recovery is inferior to the polyurethane-urea elastic fiber or the stretching fatigue becomes larger than that of a polyurethane-urea elastic fiber. In other words, they lack wear-comfort and durability for use as utility clothing. Particularly, the polyether ester elastic fiber not only lacks elongation as an elastic fiber but also has a larger variation in stress relative to the elongation to result in a tight feeling not corresponding to the physical motion. Also, since these elastic fibers are poor in heat-durability, the elastic fibers in the fabric may be damaged or broken in the field, for example, of stretch outer wear in which a high-temperature treatment is necessary or the field, for example, of foundation garment which is difficult to color-match and necessitates the repetition of dyeing, whereby the aesthetic appearance of the products is deteriorated.
Thus, if thermosettability could be imparted to the polyurethane-urea elastic fiber without sacrificing the heat-durability and the elastic function thereof, this fiber could be advantageously used in such fields.
For the purpose of improving the thermosettability of polyurethane-urea elastic fiber with an excellent elastic function, a polyurethane-urea elastic fiber is proposed, in Japanese Unexamined Patent Publication (Kokai) No. 3-97915, which is mainly composed of polyether and in which a terminal prepolymer of isocyanate is chain-extended with a specific mixed diamine, and another polyurethane-urea elastic fiber is proposed, in Japanese Unexamined Patent Publication (Kokai) No. 8-113824, in which diamine, monoamine and prepolymer are polymerized with each other at a specific ratio. In Japanese Unexamined Patent Publication (Kokai) No. 7-150417 a polyurethane-urea elastic fiber in which an alkali metal salt is incorporated therein at a low concentration. The applicant of this application has also disclosed, in Japanese Unexamined Patent Publication (Kokai) No. 7-316922, a further polyurethane-urea elastic fiber and a method for producing the same in which a thermoplastic polymer of any of a specific polyacrylonitrile type polymer, a specific polyurethane polymer and a specific styrene-maleic anhydride copolymer in a range from 1 to 14% by weight is added. However, in all cases, the improvement in thermosettability of the conventional polyurethane-urea elastic fiber is discernible but may be unsatisfactory as well as there being cases in which the elastic function of the polyurethane-urea elastic fiber may be sacrified or the yarn breakage may occur to disturb the spinning operation.
The polyurethane-urea elastic fiber is always mixed with polyamide fiber or polyester fiber and is subjected to a dyeing treatment. An acid dye is mainly used for dyeing the mixture with the polyamide fiber. Since there is no seat group for the acid dye in the polyurethane-urea polymer, most of the dye is distributed to the polyamide fiber, while the elastic fiber is hardly dyed. On the other hand, a disperse dye is mainly used for dyeing the mixture with the polyester fiber. Although the disperse dye easily enters the elastic fiber, it is almost all removed therefrom during the reduction-scouring treatment after the dyeing whereby the elastic fiber is hardly dyed. There may be a case wherein the elastic fiber appears to be dyed if the reduction-scouring treatment is insufficient. In such a case, the dye is removed from the elastic fiber during the laundering or dry-cleaning to deteriorate the color fastness as a whole. Particularly, when dyed in a deep color, if the elastic fiber is not dyed even though the polyamide or polyester fiber has been dyed, there is a problem in that the color tone of the fabric lacks the deepness or the elastic fiber shines brightly or whitely when the fabric is stretched (a so-called “grinning”).
There have almost been no proposals in the prior art for satisfactorily solving the above-mentioned problems, by an improvement in the polyurethane-urea fiber itself, or methods for producing a polyurethane-urea elastic fiber excellent in thermosettability as well as in elastic function under the stable spinning condition.
An object of the present invention is to solve the above problems in the prior art and provide a polyurethane-urea elastic fiber excellent in elastic function, heat-durability and thermosettability as well as improved in dyeability to have a good color fastness. Another object of the present invention is to provide a polyurethane-urea elastic fiber capable of manufacturing a fabric excellent in dyeability, shape-retaining property and elastic function as well as free from the grinning phenomenon. A further important object of the present invention is to provide a method for producing a modified polyurethane-urea fiber excellent in elastic function, as described above, in a stable spinning state.
DISCLOSURE OF THE INVENTION
The present inventors have found that a polyurethane-urea elastic fiber containing a specific urea compound, described later, could be modified to be uniquely excellent in elastic function and heat-durability as well as have good thermosettability and dyeability, and such a modified fiber could be produced under a stable spinning condition. Thus, the present invention has been completed.
The present invention is a polyurethane-urea elastic fiber obtained by incorporating a urea compound, in a range from 1 to 15% by weight, in a polyurethane-urea polymer, the urea compound being prepared by reacting together the following compounds:
(a) a nitrogen-con
Doi Masanori
Tsuru Keisuke
Asahi Kasei Kabushiki Kaisha
Edwards Newton
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