Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Shaping by extrusion
Patent
1990-06-22
1993-04-20
Tentoni, Leo B.
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Shaping by extrusion
26417713, 264342RE, D01D 512, D02J 122
Patent
active
052040410
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a non-woven fabric with a favorable soft hand and a superior mechanical strength and elongation, and to polyester fibers for the production of the former.
2. Background Art
The technique for the production of a wet type non-woven fabric by utilizing chopped fine polyester fibers is known in the art, as disclosed in Japanese Unexamined Patent Publication (Kokai) Nos. 57-11209, 57-16916 or 57-139554. When such fine polyester fibers are produced by a conventional process, problems arise of a lower productivity due to a low discharge rate of a fiber per spinneret and of a high rate fiber breakage during the spinning operation due to a finer thickness of the fibers, which increase production costs. Moreover, the resultant non-woven fabric cannot provide a satisfactory quality due to many defects generated therein during a paper making process, although having a desirable soft hand.
Methods of obtaining fine polyester fibers through a flow drawing process have been disclosed in Japanese Examined Patent Publication (Kokoku) Nos. 28-617, 36-20772, 43-16670, 55-6734, and 55-14171, but no proposals have been made for the utilization of fibers obtained from these processes, as a material for a wet type non-woven fabric; because the fine polyester fibers obtained from a flow drawing process are sticky and have a poor openability, and thus many defects tend to occur during the paper making process.
Further, it is known to produce a wet type non-woven fabric with undrawn polyester fibers, but the undrawn polyester fibers obtained from a conventional spinning system have a thickness of at least 1 denier, and if thinner fibers are desired, a special quenching device must be used in the spinning system, as proposed in Japanese Examined Patent Publication (Kokoku) No. 63-17921. Nevertheless, the spinning conditions remain unsatisfactory even though such a device is utilized.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the above drawbacks of the prior arts and to provide a novel method of producing ultra-fine polyester fibers through a flow drawing process, which fibers can be used for preparing a wet type non-woven fabric.
The above object is achieved by a method according to the present invention of producing ultra-fine polyester fibers, comprising the steps of: obtaining undrawn fibers by melt-spinning a co-polyester having an intrinsic viscosity of from 0.35 to 0.50, and containing repeating units which are composed mainly of ethylene-terephthalate containing from 0.5 mol % to 7.0 mol % of 5-sodiumsulfoisophthalic acid and 0.5 mol % to 10 mol % of isophthalic acid; and flow-drawing the undrawn fibers at a draw ratio of more than 5 times.
In one variant of this method, the ultra-fine polyester fibers obtained through the flow drawing of more than 5 times may be further subjected to a neck drawing process, to produce more shrinkable fibers.
The fibers obtained by the neck drawing process may be subjected to a shrinking process using a wet heat conditioned to contract the fibers by from 2% to 40%, to obtain modified fibers with a lower shrinkage rate.
The flow drawing process is preferably carried out while a polyether block polymer of from 0.02% to 5.0% by weight is imparted to the fibers.
The thus-obtained polyester fibers have a monofilament thickness of less than 1 denier, preferably less than 0.5 denier, more preferably less than 0.3 denier, and further preferably, have a non-circular cross section with projections on the periphery thereof.
Another object of the present invention is to provide a wet type non-woven fabric with superior qualities derived from the characteristics of the thus-obtained ultra-fine polyester fibers.
According to a further aspect of the present invention, a wet type non-woven fabric is provided through a paper making process by using a material comprising at least one of three type ultra-fine polyester fibers A, B and C; the fiber A being prepared only through the flow drawing proces
REFERENCES:
patent: 3748844 (1973-07-01), Pacofsky
patent: 3914501 (1975-10-01), Miller et al.
Kobayashi Tsukasa
Tashiro Mikio
Uemura Ryuji
Teijin Limited
Tentoni Leo B.
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