Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
1999-09-17
2001-05-08
Edwards, N. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S373000, C428S374000, C428S372000
Reexamination Certificate
active
06228490
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a polyolefin-based splittable conjugated fiber having excellent splittability, and to a nonwoven fabric and an absorbent article using the same. More particularly, the present invention relates to a polyolefin-based splittable conjugated fiber that can display excellent characteristics with extra fine fiber generated by splitting, and which can be used suitably in battery separators, wipers, filters, and the like, and a nonwoven fabric using the same, and to an absorbent article such as a disposable diaper, sanitary napkin, menstrual sheet, incontinence pad, nursing pad, or the like, in which such a nonwoven fabric is partially used.
BACKGROUND OF THE INVENTION
Traditionally, splittable conjugated fiber has been used in various applications, because it forms extra fine fiber by splitting treatment.
As a conventional olefin-based splittable conjugated fiber, Publication of Examined Japanese Patent Application (Tokko) No. HEI 3-137222 (JP 3-137222 B) discloses one in which the hardness of a polymer is determined, and Publication of Unexamined Japanese Patent Application (Tokkai) No. HEI 5-321018 (JP 5-321018 A) discloses one in which a polypropylene resin is combined with a polyethylene resin blended with a polypropylene resin.
In the invention disclosed in the above-mentioned Publication of Japanese Examined Patent Application (Tokko) No. HEI 3-137222, it is described that the fiber can be split easily when the polymer itself has a hardness of not less than a certain value. However, there was a problem in that, when the polymer has a high hardness, its spinnability as well as its stretchability become poor, so that the fineness of the fiber before being split becomes large. Moreover, in the invention disclosed in the above-mentioned Publication of Unexamined Japanese Patent Application (Tokkai) No. HEI 5-321018, a polypropylene resin (a) is used as one component of the splittable conjugated fiber, and a blended resin (b) in which a polyethylene resin is blended with a polypropylene resin is used as the other component. However, when a polyethylene resin is blended with a polypropylene resin, it has an increased compatibility with the polypropylene resin (a), so that these components become difficult to split. Thus, it is necessary to increase the physical impact to split the splittable conjugated fiber. However, when the physical impact is increased, unevenness is generated in the density of the fiber existing in the obtained nonwoven fabric, so that non-uniformity is generated, and formation is deteriorated. Moreover, production of a nonwoven fabric having a low basis weight, for example, a nonwoven fabric for sanitary materials, becomes difficult. Thus, it was not satisfactory at all.
SUMMARY OF THE INVENTION
The present invention has an object to provide an olefin-based splittable conjugated fiber that can improve these drawbacks, and a nonwoven fabric using the same, and an absorbent article.
That is, it is an object of the present invention to provide an olefin-based splittable conjugated fiber that has good spinnability and good stretchability, and is easy to split.
It is another object of the present invention to provide a nonwoven fabric that is soft and uniform and has a good formation by solving the difficulty in splitting, which has been a conventional problem for a polyolefin-based splittable conjugated fiber, and to provide an absorbent article in which such a nonwoven fabric is partially used.
The present invention is characterized as follows:
(1) A polyolefin-based splittable conjugated fiber which contains a peroxide and has a MFR of at least 30 g/10 min.
(2) The polyolefin-based splittable conjugated fiber according to the item (1), which comprises a polypropylene resin and a polyethylene resin.
(3) The polyolefin-based splittable conjugated fiber according to the item (1), wherein the peroxide is dialkylperoxide.
(4) The polyolefin-based splittable conjugated fiber according to the item (1), wherein the content of the peroxide is from 0.005 to 0.3 wt. % based on the total weight of the polyolefin-based splittable conjugated fiber.
(5) The polyolefin-based splittable conjugated fiber according to the item (1), which has a modified cross section (non-circular cross section).
(6) A nonwoven fabric, comprising split fibers obtained by splitting the splittable conjugated fiber according to the item (1).
(7) An absorbent article using the nonwoven fabric according to the item (6) in a part thereof.
REFERENCES:
patent: 5683814 (1997-11-01), Kakita et al.
patent: 5759926 (1998-06-01), Pike et al.
patent: 5783503 (1998-07-01), Gillespie et al.
patent: 6004673 (1999-12-01), Nishijima
patent: 6080471 (2000-06-01), Shigematsu et al.
patent: 3-137222 (1991-06-01), None
patent: 5-321018 (1993-12-01), None
Nagano Koki
Tsutsui Toshihiko
Chisso Corporation
Edwards N.
Merchant & Gould P.C.
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