Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2001-06-21
2003-01-07
Edwards, Newton (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S395000, C428S370000, 36, 36, 36
Reexamination Certificate
active
06503622
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a texturized, combined polyester multifilament yarn and a process for producing the same. More particularly, the present invention relates to a texturized, combined polyester multifilament yarn comprising two or more types of texturized polyester multifilaments, different in polymer composition thereof from each other, combined with each other to form a combined yarn and having an enhanced bulkiness, and a process for producing the yarn.
BACKGROUND ART
Currently various types of texturized polyester multifilament yarns are produced from two or more types of polyester multifilaments different in elongation and/or thermal shrinkage from each other by draw-false twisting or drawing procedures in which the two or more different types of undrawn multifilaments are processed altogether. In this procedure, a difference in real filament length between the two or more different types of multifilaments is increased due to the differences in the elongation property and thermal shrinkage property between them, to thereby expand the gap spaces between the texturized individual filaments contained in the combined yarn and to enhance the bulkiness of the resultant texturized, combined multifilament yarn.
The term “real filament length” means a length of a filament in a straightened condition.
The two or more types of undrawn polyester multifilaments different in elongation and/or thermal shrinkage and usable for the production of the texturized multifilament yarn are briefly classified into the following two groups.
Group 1
Two or more different types of multifilaments are. melt-spun through melt-spinning orifices; and then the resultant undrawn multi-filaments are separately wound up around two or more different bobbins. These yarns are referred to as separately wound multifilament yarns.
Group 2
Two or more different types of multi-filaments are melt-spun through melt-spinning orifices; the resultant undrawn individual multifilaments are combined with each other; and the combined multifilaments are wound around a single bobbin. The yarn is referred to as a melt-spun, combined multifilament yarn.
The separately wound multifilament yarns (group 1) are advantageous in that since the melt-spun multifilament yarns are wound separately from each other, and thus the polymer composition of and yarn-production conditions for each yarn can be widely varied, variety in combinations of the different types of the multifilaments can be significantly enhanced. However, the separately wound multifilament yarns are disadvantageous in that, in the production of two or more different types of multifilament yarns, two or more separate apparatuses are necessary, and thus the productivity of the combined multifilament yarn is low. Also, the separately wound multifilament yarns are disadvantageous in that when the two or more different types of separately wound multifilaments are combined with each other to form a combined yarn, it is difficult to smoothly combine the individual multifilaments with each other during the texturized yarn-forming procedure, and the multifilaments which have a longer filament length and should be mainly located in an outer layer of the resultant texturized, combined multifilament yarn to serve as sheath filaments for the yarn, are not fixed around other multifilaments which have a shorter filament length and should be mainly located in an core portion of the resultant textured, combined multifilament yarn to serve as core filaments for the yarn, and thus the longer filament length sheath filaments do not contribute to sufficiently enhancing the bulkiness of the resultant texturized, combined multifilament yarn.
The melt-spun, combined multifilament yarn (group 2) is advantageous in that since a plurality of types of multifilaments are wound to form a single package, the combined multifilament yarn can be produced by a single melt-spinning apparatus; and since the plurality of types of the melt-spun multifilaments are combined before the winding procedure, the melt-spun individual multifilaments are easily combined with each other; and in the resultant texturized, combined multifilament yarn, the longer filament length multifilaments can be easily located in the outer layer of the resultant yarn to serve as sheath filaments and contribute to enhancing the bulkiness of the resultant yarn. However, since the melt-spun, combined multifilament yarn is produced by a single melt-spinning apparatus, the melt-spinning conditions, for a plurality of types of the multifilaments, are difficult to change widely and independently; large differences in the elongation property and shrinkage property are difficult to produce between the two or more types of the multifilaments; and thus production of a texturized, combined multifilament yarn in which the difference in real filament length between the two or more types of multifilaments is large enough to obtain a high bulkiness of the yarn, is difficult.
Japanese Unexamined Patent Publication No. 58-98418 discloses a process in which only the advantages of both the separately wound multifilaments and the melt-spun, combined multifilaments appear. In this process, a specific polymer, for example, a polymethyl methacrylate, is added to one type of multifilaments for a combined multifilament yarn, to thereby greatly increase the elongation of the polymethyl methacrylate-added multifilaments in comparison with that of the non-polymethyl methacrylate-added multifilaments, and thus a texturized combined multifilament yarn having a large difference in real filament length between two or more types of multifilaments, which large difference was believed to be unobtainable by the conventional melt-spun, combined multifilaments, can be obtained.
However, the inventors of the present invention studied the above-mentioned process and found that in a stage of the process in which a difference in the real filament length is created between the two or more types of melt-spun multifilaments, the combination of the individual melt-spun multifilaments with each other proceeds to an excessive extent, and thus the combined melt-spun individual multifilaments are restricted in the movement in relation to each other; thus, the longer filament length multifilaments are difficult to be located in the outer layer of the resultant combined yarn; and the resultant combined yarn exhibit an insufficient bulkiness, even when the filament length difference, per se, is large.
Japanese Unexamined Patent Publication No. 63-42,913 discloses a copolymerization of isophthalic acid into a polyester molecule chain, in place of an addition of polymethyl methacrylate. According to the publication, the copolymerization of isophthalic acid contributes to increasing the difference in shrinkage between two or more types of melt-spun multifilaments in the melt-spun, combined multifilament yarn and enables the resultant bulky texturized yarn to exhibit a large difference in the real filament length between the two or more types of multifilaments, similar to that in Japanese Unexamined Patent Publication No 58-98418. However, it has been found by the inventors of the present invention that in the production of the bulky texturized multifilament yarn of Japanese Unexamined Patent Publication No. 63-42913, in which isophthalic acid is employed, the melt-spun multifilaments are combined to an excessive extent in the stage of creating the difference in the real filament length between two or more types of multi-filaments, and thus the resultant texturized, combined multifilament yarn exhibits an unsatisfactory bulkiness even when a large filament length difference is created. Accordingly, the conventional art has not yet succeeded to provide a texturized, combined polyester multifilament yarn in which longer multifilaments are satisfactorily located in the outer layer of the yarn to form a bulky sheath layer, the difference in the filament length between two or more types of multifilaments is sufficiently large and the bulkiness of the resultant combine
Iohara Koichi
Ogawa Kimihiro
Yoshimura Mie
Edwards Newton
Teijin Limited
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