Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Staple length fiber
Reexamination Certificate
2001-08-08
2002-04-16
Edwards, N. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Staple length fiber
C428S364000, C428S376000, C428S398000, C428S395000
Reexamination Certificate
active
06372343
ABSTRACT:
TECHNICAL FIELD
This invention relates to polyester fibers having three-dimensional crimps and a fiber structure using the same, and more particularly it relates to crimped polyester fiber good in carding performance and capable of providing products rich in bulkiness and good in compression durability such as nonwoven fabrics or waddings and a fiber structure comprising said crimped polyester fibers and heat-bonding conjugated staple fibers.
BACKGROUND OF THE INVENTION
Polyester fibers, especially polyethylene terephthalate fibers are excellent in mechanical strength and chemical and heat resistances or the like and have widely been used for applications such as clothes or industrial uses. The polyethylene terephthalate fibers themselves, however, are flat and deficient in bulkiness. Various attempts to improve the bulkiness, therefore, have been made in uses such as the nonwoven fabrics or waddings requiring a bulky feeling by crimping the polyethylene terephthalate fibers.
Although the above products produced from the crimped polyethylene terephthalate fibers have high bulkiness just after the use, there are problems that disappearance of compression durability is readily caused when used for a long period.
In contrast to this, JP-A No. 11-189938 (1999) (hereunder, JP-A means Japanese unexamined patent publication) proposes polytrimethylene terephthalate staple fibers having crimps in which stretch elastic recovery ratio, flexing recovery ratio and the like are specified, and such staple fibers are improved in compression durability as compared with that of crimped fibers comprising polyethylene terephthalate. Said staple fibers, however, are produced by a method of heat-treating the polytrimethylene terephthalate fibers, then carrying out crimping with a stuffer crimper and cutting the crimped fibers into the staple fibers, and there are problems that the staple fibers have merely planar, the so-called two-dimensional crimps and the bulkiness of the products obtained from said fibers is insufficient. Furthermore, U.S. Pat. No. 3,681,188 proposes fibers produced by imparting asymmetric birefringence across filament diameters to extruded filaments of polytrimethylene terephthalate by asymmetric quenching and developing three-dimensional crimps. The crimped fibers obtained by the methods disclosed in the prior art, however, have an extremely small number of crimps or an excessively high percentage crimp, and there are problems that only products insufficient in bulkiness or compression durability are obtained from such crimped fibers and winding up of a web around cylinders or rollers, waste fibers, web breakage and the like are caused in a carding step.
On the other hand, polyester staple fibers, especially polyethylene terephthalate (hereinafter sometimes abbreviated to PET)-based staple fibers have hitherto been extensively used as wadding materials for beddings, furniture, clothes or the like. Above all, a fiber structure obtained by mixing such polyester staple fibers with heat-bonding conjugated fibers and heat-treating the mixed fibers is utilized as a urethane substitute material for various applications such as cushioning materials, padding materials of futons, automotive sheets or bed mats. International Application Published under the Patent Cooperation Treaty WO91/19032, JP-A No. 4-240219 (1992) and the like are proposed as fiber structures obtained by using the above heat-bonding conjugated fibers; however, there has been a demand for such fiber structure to further improve the compression durability.
DISCLOSURE OF THE INVENTION
As a result of intensive investigations made to achieve the above problems, the present inventors et al. have found that not only the carding performance is improved but also bulkiness and compression durability of the resulting products are remarkably improved when using crimped polyester fibers comprising polytrimethylene terephthalate and having moderate three-dimensional crimps and a high crimp modulus of elasticity, thus accomplishing the present invention. Furthermore, it has been found that the bulkiness and compression durability are remarkably improved as compared with those of conventionally proposed fiber structures when combining the above crimped polyester fibers with heat-bonding conjugated fibers and providing a fiber structure.
Thereby, according to this invention, there are proposed crimped polyester fibers characterized as comprising a polytrimethylene terephthalate-based polyester and having three-dimensional crimps with a number of crimps of 9 to 30 peaks/25 mm and a crimp ratio of 20 to 50% and further a crimp modulus of elasticity of 80% or above and a fiber structure characterized as comprising staple fibers of the above crimped polyester fibers and heat-bonding conjugated staple fibers in a weight ratio of the staple fibers of said crimped polyester fibers to said heat-bonding conjugated staple fibers of 30:70 to 95:5 and having heat-bonded spots formed at least partially in contact points of the staple fibers of said crimped polyester fibers with said heat-bonding conjugated staple fibers and/or contact points of the mutual heat-bonding conjugated staple fibers.
BEST MODE FOR CARRYING OUT THE INVENTION
The polytrimethylene terephthalate based polyester described in this invention is a polyester comprising a trimethylene terephthalate unit as a main recurring unit and may be a polyester wherein a third component in an amount within the range so as not to inhibit the object of this invention, for example, 15 mole % or less, perferably 5 mole % or less based on an acid component is copolymerized.
Various kinds such as an acid component, for example, isophthalic acid, succinic acid, adipic acid, 2,6-naphthalenedicarboxylic acid or a metal sulfoisophthalic acid and a glycol component or the like, for example, 1,4-butanediol, 1,6-hexanediol, cyclohexanediol or cyclohexanedimethanol can be used as the preferably used third component and may suitably be used by taking the spinning property or the like into consideration.
Various additives, for example, a delustering agent, a heat stabilizer, a defoaming agent, an orthochromatic agent, a flame retardant, an antioxidant, an ultraviolet absorber, an infrared absorber, a fluorescent brightener or a color pigment, as necessary, can be added.
In this invention, it is important that not only the crimped polyester fibers of this invention are crimped fibers comprising the above polytrimethylene terephthalate-based polyester but also said fibers have three-dimensional crimps satisfying the number of crimps and crimp ratio described below and the crimp modulus of elasticity simultaneously satisfying the following requirements. Thus, products good in carding performance and excellent in bulkiness and compression durability can be obtained.
That is, the number of crimps of the crimped polyester fibers of t is invention must be 9 to 30 peaks/25 mm and is more preferably 11 to 20 peaks/25 mm. When the number of crimps is below 9 peaks/25 mm, the bulkiness of products obtained from said fibers is insufficient. On the other hand, when the number of crimps exceeds 30 peaks/25 mm, the entangling property among the fibers becomes too high and the carding performance is deteriorated.
The crimp ratio of said polyester fibers must be 20 to 50% and is more preferably 30 to 40%. When said crimp ratio is below 20%, the entangling property among the mutual fibers is low, the carding performance is deteriorated, and sufficient bulkiness cannot be obtained. On the other hand, when the crimp ratio exceeds 50%, not only the entangling property becomes so high that tangling is caused to deteriorate the carding performance but also the resulting web becomes nonuniform.
Further, the crimp modulus of elasticity of said polyester fibers must be 80% or above and is more preferably 85% or above. When the crimp modulus of elasticity is below 80%, the carding performance is extremely deteriorated because the disappearance of compression durability of crimps is great, and the fibers are easily wound up around
Baba Kenji
Tashiro Mikio
Tsukamoto Ryoji
Yamada Toshihiro
Edwards N.
Sughrue & Mion, PLLC
Teijin Limited
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