Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2000-07-28
2002-10-22
Kelly, Cynthia H. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S364000, C428S375000, C428S394000
Reexamination Certificate
active
06468655
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a poly (trimethylene terephthalate) fiber, suited for use in clothing, which has excellent smoothness, abrasion resistance, cohesiveness and has an anti-static electricity property. The fiber also has good processability during various steps from the spinning step to the post-processing step, for example, during the spinning and drawing steps, unwinding step from yarn package, false-twist texturing, weaving, and knitting processings, and extremely good wound form of yarn package, thus providing a knitted/woven fabric having good quality such as elastic recovery, soft hand and homogeneity.
BACKGROUND ART
Poly(trimethylene terephthalate) (hereinafter abbreviated to “PTT”) obtained by polycondensing terephthalic acid or a lower alcohol ester of terephthalic acid represented by dimethyl terephthalate with trimethylene glycol (1,3-propanediol) is an epochal polymer having both properties which resemble those of polyamide, for example, excellent elastic recoverly, low elastic modulus (soft hand) and ease of dyeing, and properties which resemble to those of poly(ethylene terephthalate) (hereinafter abbreviated to “PET”), for example, light resistance, thermosetting property, dimensional stability and low water absorption. PTT has been applied to products such as clothing, BCF carpet, brushes and tennis gut due to the above-described features (Unexamined Patent Publication (Kokai) Nos. 9-3724, 8-173244 and 5-262862).
One of fibrous forms capable of employing the above-described properties of the PTT fiber as much as possible includes a false-twist textured yarn. The false-twist textured yarn of the. PTT fiber can serve as a markedly excellent raw yarn for stretch material because it is superior in elastic modulus and softness to known synthetic fibers, for example, polyester fiber such as PET fiber (Unexamined Patent Publication (Kokai) No. 9-78373).
On spinning and false-twist texturing of the polyester fiber represented by the PET fiber, it is essential to apply a finishing agent to the surface of the fiber. If the spinning and false-twist texturing are conducted without applying the finishing agent on the surface of the fiber, friction and static electricity increase to cause nap and yarn cutting, thus making it impossible to conduct industrial production. In the case where the false-twist texturing of the PET fiber is conducted, a finishing agent containing 70% by weight or more of a polyether prepared by copolymerizing polyoxyethylene with polyoxypropylene (hereinafter referred to as “polyether”) is usually applied to the surface of the fiber (e.g. Unexamined Patent Publication (Kokai) No. 63-57548). The reason is as follows. That is, since heating at 200° C. or higher is required in the thermosetting step in the false-twist texturing of the PET fiber, it becomes necessary to use a finishing agent comprising a polyether, which is superior in heat resistance, as a principal component in order to inhibit staining of the heater caused by heat deterioration, although the friction coefficient increases.
With respect to a finishing agent for false twisting of the PTT fiber, an optimum composition has never been suggested, heretofore. The reason is as follows. That is, there has not been a method of preparing trimethylene glycol as a raw material of PTT until recently and an industrial study of production of the PTT fiber has never been made.
Considering the finishing agent for false twisting of the PET fiber, it may be supposed that the finishing agent for false twisting of the PET fiber can be used for the PTT fiber as it is because the PTT fiber and PET fiber resemble each other in chemical structure. As is apparent from the present inventors' study, a finishing agent suited for the PTT fiber must be designed for the following two reasons. That is, (1) the PTT fiber and the polyester fiber other than the PTT fiber, which is represented by the PET fiber, differ drastically in physical properties of the fiber, in particular, the PTT fiber has a large friction coefficient and abrasive resistance, and (2) they differ drastically in optimum temperature conditions of the thermosetting step in the false-twist texturing step so that the thermosetting temperature of the PTT fiber must be set to a low temperature.
First, it will be shown that the PTT fiber has a large friction coefficient and abrasive resistance.
The PTT fiber exhibits such properties that the PTT fiber contracts easily to an original length when stretched like an elastic yarn because molecules of the PTT fiber bend largely in a Z-shape. Due to such elastic properties, when a single yarn is contacted with a roll, guide, hot plate or pin, or single yarns are contacted with each other in a state where a tension is applied in the spinning and processing step, the contact area increases, thereby to enhance the friction coefficient. When the spinning and drawing are continued in such a state, a nap is liable to occur. It has also been found that a nap of the fiber is liable to occur when the PTT fibers are rubbed with each other or the PTT fiber is strongly rubbed with the material other than the PTT fiber at the fiber side. It is assumed that such an ease of abrading depends on a Z-shaped bent molecular structure and that such a Z-shaped structure leads to reduction in an intermolecular force between adjacent molecules thereby to reduce a cohesive force acted in the intermolecular direction, thus deteriorating abrasion properties. On the other hand, the other polyester fiber, for example, PET fiber and poly (butylene terephthalate) fiber hardly exhibit elastic properties because its molecular chain is in the state of being extended to full length. The intermolecular cohesive force also tends to increase. Therefore, problems concerning friction properties and abrasion resistance of the PTT fiber hardly occur. If the finishing agent for false twisting of the PET fiber is applied to the PTT fiber, a polyether as a principal component of the finishing agent has a small effect of reducing the friction coefficient thereby to cause nap and yarn cutting. Therefore, the finishing agent for false twisting of the PET fiber can not be used industrially.
Next, it will be shown that the optimum temperature of the thermosetting step in the false-twist texturing step must be set to a lower temperature than that of the PET fiber.
As described previously, the thermosetting temperature in the false-twist texturing of the PET fiber exceeds 200° C., but the PTT fiber cannot be thermally set at a temperature of 190° C. or higher according to the present inventors' study. The reason is as follows. That is, when the PTT fiber is heated to a temperature of 190° C. or higher, the tenacity and elongation are drastically lowered and cutting of the fiber is liable to Accordingly, the thermosetting temperature of the PTT fiber in the false-twist texturing is usually within a range from 140 to 190° C. Since the glass transition point of the PTT fiber is lower than that of the PET fiber even at a low thermosetting temperature, it becomes possible to conduct sufficient thermosetting. Accordingly, it is not necessary to secure the heat resistance at 200° C. or higher in the finishing agent for false twisting of the PTT fiber so that it is not required to expressly use a finishing agent comprising a polyether component as a principal component, which has a poor effect of lowering the friction coefficient of the surface of the fiber.
As described above, a study on a finishing agent for false twisting and weaving/knitting, which is suited for the PTT fiber, has hardly been made. At present, a suggestion with respect to the necessity of design of a finishing agent in consideration of specific frictional abrasion properties of the PTT fiber and conditions of false twisting, and a means for solving the problem, have not been made.
Accordingly, the design of a finishing agent having a performance capable of solving problems due to the above-described specific properties of the fiber is indispensable to the indus
Fujimoto Katsuhiro
Kato Jinichiro
Asahi Kasei Kabushiki Kaisha
Gray J. M.
Kelly Cynthia H.
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