Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2001-11-26
2003-02-04
Edwards, N. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S395000
Reexamination Certificate
active
06514607
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a sewing thread having stretchability and to sewn articles prepared using the sewing thread.
BACKGROUND ART
For example, when a fabric having stretchability is sewn with a commonly used sewing thread having no stretchability, it has heretofore been natural that the stretchability of the fabric in the seamed portions is lowered, and the advantage of the fabric has not been utilized. Moreover, when an excessive elongating force is applied to the seams of a sewn stretchable fabric, the sewn fabric has a disadvantage that the sewing thread having no stretchability is easily broken.
Accordingly, when stretchability must be given to the seams, the following has been practiced: the stretchability of the seams is manifested by forming seams having a structure of a multi-thread chain stitch, an overlock stitch or a zigzag stitch. However, these seams have the following drawbacks: a special sewing machine is required in order to form the structures; formation of the seams requires much time; a large amount of a sewing thread is used; and the seams have a poor appearance. Moreover, the stretchability of the fabric in the seamed portions is not necessarily satisfactory.
Japanese Unexamined Patent Publication (Kokai) No. 1-260030 and No. 2-26945 propose sewing threads used for sewing stretchable fabrics. These known sewing threads are prepared by doubler-twisting an elastic yarn such as a polyurethane-based yarn and a soluble yarn or covering an elastic yarn with a soluble yarn. In a sewing method using the sewing threads, elastic yarns alone are left in the stitched portions by dissolving and removing the soluble yarns after sewing. In these proposals, an attempt is made to solve the following problems of the sewing method using an elastic yarn alone, by doubler and twisting an elastic yarn and a nonelastic soluble yarn in combination or covering an elastic yarn with a nonelastic soluble yarn so that elongation of the elastic yarn is suppressed and the friction resistance is decreased during sewing: the sewing performance is poor; puckering is produced; and the sewn appearance is poor. However, this sewing method has the following disadvantages: in order to manifest the elasticity of the elastic yarn, the step of dissolving and removing the soluble yarn is required so that the sewing cost is increased; and perforations clearly remain in the stitched portions of sewn articles to impair the sewn appearance.
On the other hand, Japanese Unexamined Patent Publication (Kokai) No. 5-321066 discloses, as a composite sewing thread that is excellent in high speed sewing performance and that forms seams excellent in tenacity and appearance, a composite sewing thread that is formed from a composite yarn prepared by covering as a core yarn a high tenacity filaments synthetic yarn such as a poly(ethylene terephthalate) yarn by staple fibers; the core yarn has a breaking strength of 7.5 g/d (6.6 cN/dtex) or more, a dry heat shrinkage of 4% or less at 150° C., and a stress at a 5% elongation of 2.0 g/d (1.8 cN/dtex) or more. However, since the known composite sewing thread has no elastic stretchability, the sewing thread has the same disadvantages as those of the above common sewing threads that have no elastic stretchability. Moreover, according to the study of the present inventors, it has been significantly difficult to obtain a high strength poly(trimethylene terephthalate) yarn that has a breaking strength of 6.6 cN/dtex or more although there is no description in the patent publication that suggests a poly(trimethylene terephthalate) yarn.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a stretchable sewing thread that can be used for forming lock stitch having a high stretchability, and a sewn article prepared from a stretchable fabric and having seams that have an excellent appearance and stretchability.
The present inventors have discovered that a sewing thread showing an elongation at a lower stress and an excellent elastic recovery at a high elongation can be obtained by subjecting a yarn obtained by double and twisting two to several poly(trimethylene terephthalate) multifilament yarns that have specific physical properties and specifications which will be described later to a wet heat relaxation treatment under specific conditions to cause uniform fine structural changes, namely, structural relaxation to the constituent filaments.
Furthermore, the present inventors have found that a sewing thread obtained by such a method as explained above and showing specific tensile elongation characteristics has an excellent stretchability and can solve the problems mentioned above, and thus achieved the present invention.
That is, the present invention provides a sewing thread formed from poly(trimethylene terephthalate) filaments yarns, the sewing thread being characterized in that the sewing thread shows a stress at a 5% elongation of a tensile elongation curve of from 0.4 to 1.2 cN/dtex and a stress at a 30% elongation of from 1.4 to 2.2 cN/dtex.
The present invention further relates to a sewn article prepared by sewing a fabric using such a sewing thread.
The present invention will be explained below in detail.
In the present invention, a poly(trimethylene terephthalate) yarn designates a yarn composed of a polyester that has trimethylene terephthalate repeating units as principal repeating units and that contains the trimethylene terephthalate units in an amount of about 50% by mol or more, preferably 70% by mol or more, more preferably 80% by mol or more, still more preferably 90% by mol or more. The poly(trimethylene terephthalate) yarn according to the present invention therefore includes a polyester yarn composed of poly(trimethylene terephthalate) that contains as a third component of the polyester other acid components and/or glycol components in a total amount of about 50% by mol or less, preferably 30% by mol or less, more preferably 20% by mol or less, still more preferably 10% by mol or less.
Poly(trimethylene terephthalate) is synthesized by combining terephthalic acid or its functional derivative and trimethylene glycol or its functional derivative in the presence of a catalyst under suitable reaction conditions. In the course of the synthesis, one or two or more suitable third components may also be added to form a copolymerized polyester.
Examples of the third components to be added include aliphatic dicarboxylic acids such as oxalic acid and adipic acid, alicylic dicarboxylic acids such as cyclohexanedicarboxylic acid, aromatic dicarboxylic acids such as isophthalic acid and sodium sulfoisophthalate, aliphatic glycols such as ethylene glycol, 1,2-propylene glycol and tetramethylene glycol, alicyclic glycols such as cyclohexanedimethanol, aliphatic glycols each having an aromatic group such as 1,4-bis(&bgr;-hydroxyethoxy) benzene, polyether glycols such as polyethylene glycol and polypropylene glycol, aliphatic oxycarboxylic acids such as (&ohgr;-oxycaproic acid and aromatic oxycarboxylic acid such as p-oxybenzoic acid. Moreover, a compound having one or three or more ester-forming functional groups such as benzoic acid or glycerin may also be employed so long as the resultant polymers are substantially linear.
The poly(trimethylene terephthalate) yarn used in the present invention is generally a yarn produced by melt spinning the poly(trimethylene terephthalate) polymer explained above. The poly(trimethylene terephthalate) yarn may also be a yarn produced by separately synthesizing such a polyester other than poly(trimethylene terephthalate) as poly(ethylene terephthalate), nylon and poly(trimethylene terephthalate), and blending the polymers (polymer blending); the yarn may also be one produced by composite spinning (sheath core, side-by-side or the like).
The poly(trimethylene terephthalate) yarn herein may contain delustering agents such as titanium dioxide, stabilizing agents such as phosphoric acid, ultraviolet-ray absorbers such as a hydroxybenzophenone derivative, nucleating agents such as talc, lub
Oue Kazuto
Yoneda Keiko
Asahi Kasei Kabushiki Kaisha
Edwards N.
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