Gas separation: apparatus – Electric field separation apparatus – Electric charge produced by friction
Reexamination Certificate
2001-12-27
2003-06-03
Chiesa, Richard L. (Department: 1724)
Gas separation: apparatus
Electric field separation apparatus
Electric charge produced by friction
C015S209100, C055S524000, C055S528000, C055SDIG003, C096S069000, C442S110000
Reexamination Certificate
active
06572684
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to tow having good chargeability and excellent workability. More particularly, the invention relates to tow which has very good adaptability as raw material for such a processed goods as air filter, wiper, etc., and laminate derived therefrom, though it has good chargeability, since its chargeability does not influence adversely on the processing step.
2. Description of the Related Art
In fiber, particularly synthetic fiber, static electricity that is generated by friction between fiber—fiber, fiber-metal, or fiber-air is an obstacle to the process of fiber spinning, drawing, spinning or processing of non-woven fabric. This is well known to cause feather bristling, twining around a roller, and yarn breaking and result in decrease of the quality and decrease of the productivity. In order to avoid troubles caused by static electricity, various methods for reducing generation of the static electricity or for eliminating the static electricity generated have been proposed. In the former method, a fiber-processing agent is applied on the fiber surface to improve smoothness. As the latter methods, a method for applying an anti-static agent on the fiber surface, a method for using as a raw resin of synthetic fiber a resin for which a component having an anti-static property has been copolymerized, and a method for fiber spinning a mixture of resin and an anti-static agent under melting, are exemplified.
On the other hand, in recent years, a filter or wiper for collecting dust in which chargeability of fiber is utilized has been required, so that synthetic fiber having chargeability has been desired in many cases in response to such requirements. Particularly, a long and thick bundle of tow which is made by tying synthetic fiber produced in the process for yarn-making and afforded chargeability is a good raw material for the goods. In producing such a good as filter or wiper, however, when the convergence or disentanglement of tow becomes worse by influence of static electricity, workability for the goods such as a dust-collecting filter or wiper utilizing chargeability decreases markedly. Therefore, it was very difficult to obtain such tow in which the chargeability and the workability are compatible.
In a common method for producing tow in which the chargeability and the workability are compatible, an anti-static agent is applied to synthetic fiber in the process for yarn-making, and thus resulting synthetic fiber to which has adhered the anti-static agent is used in production of tow. Then, the adhered anti-static agent is washed out well with water or an organic solvent. In this step, however, it is more suitable to wash tow goods in the final shape such as filters or wipers (hereinafter sometimes referred to as the processed goods) than to wash the tow itself, because there is no risk that the workability decreases due to static electricity generated in the respective steps leading to the processed goods. Any of washing steps for the tow itself or for the processed goods of the final shape, however, require an additional step for removing water or an organic solvent adhering to the processed goods, as well as steps for drying or recovering the solvent.
Japanese Patent Laid-Open No. 214655/1993 discloses a method for coating the fiber surface with an electret thermoplastic resin such as polybutene-1, and describes that synthetic fiber having good chargeability can be provided by the method. This patent also describes that the presence of a conductive material on the surface or in the inside of the fiber is not preferred to attain the object. Therefore, the synthetic fiber is intended to be produced by a dry-fiber spinning method such as a span-bonding method or melt-blowing method in which no adhesion of any fiber-processing agent is necessary. In addition, there is an alternative method for obtaining non-woven fabrics by span lace processing in which a fiber-processing agent can be washed out. In this method, however, an additional step as mentioned above is required. In the other common method for production using no fiber-processing agent, there occurs the above-mentioned disturbance as defect of the method due to friction to decrease quality of the product and productivity. Accordingly, at present there is no method adaptable for production of tow, in which the chargeability and the workability are compatible.
SUMMARY OF THE INVENTION
The present inventors worked assiduously to develop tow which can inhibit such a harmful effect as twining on a roll or single thread snapping due to static electricity generated in the production process. As a result, it was found that tow which comprises synthetic fiber of thermoplastic resin, of which the fineness of single yarn is 0.5 to 100 dtex, in which each synthetic fiber has crimps, and the value (D/W) obtained by dividing the total fineness (D) of the tow by the tow width (W) is 1,000 to 8,000 dtex/mm, and to which a fiber-processing agent containing a polyoxyethylene higher fatty acid ester of a particular structure and a sorbitan fatty acid ester at a particular ratio has preferably adhered in a particular amount, has incompatible characters, i.e., excellent chargeability and workability in processing into a filter or wiper without causing such a harmful effect as twining on a roll or single thread snapping in the steps of producing tow. The invention was completed based on these findings. As clearly seen from the above description, the object of the invention is to provide tow having excellent workability in processing into a filter or wiper, even though it has chargeability, laminate derived therefrom and processed goods therefrom.
The present invention is constituted as follows.
(1) Chargeable tow which comprises synthetic fiber of thermoplastic resin, of which the fineness of single yarn is 0.5 to 100 deci-tex (dtex), in which each synthetic fiber has crimps, the total fineness is 10,000 to 300,000 dtex, and the value (D/W) obtained by dividing the total fineness of the tow (D) by the tow width (W) is in a range of 1,000 to 8,000 dtex/mm, and of which the leak electric resistance is 1×10
10
&OHgr; or more.
(2) Chargeable tow which comprises synthetic fiber of thermoplastic resin, of which the fineness of single yarn is 0.5 to 100 deci-tex (dtex), in which each synthetic fiber has crimps, the total fineness is 10,000 to 300,000 dtex, and the value (D/W) obtained by dividing the total fineness (D) of tow by the tow width (W) is in a range of 1,000 to 8,000 dtex/mm, and to which has adhered a fiber-processing agent containing the following components A and B (60 to 95% by weight of the component A and 5 to 40% by weight of the component B, based on the fiber-processing agent).
Component A
A mixture of a polyoxyethylene higher fatty acid ester of the following general formula (1) and one or more species of a sorbitan fatty acid ester of the following general formula (2) or (3):
Component B
Polyoxyethylene higher fatty acid ester of the following general formula (4) and/or general formula (5):
[General Formula (1)]
(In the formula, R
1
is a saturated or unsaturated aliphatic hydrocarbon group of 5 to 18 carbon atoms; and k is an integer of 2 to 50).
[General Formula (2)]
[General Formula (3)]
(In the general formulae (2) and (3), R
2
, R
3
and R
4
each is a hydroxyl group or polyoxyethylene group, wherein the polymerization degree of the polyoxyethylene group (repeated unit of the polyoxyethylene group) is 2 to 55; and R
5
is a saturated or unsaturated aliphatic hydrocarbon group of 16 to 30 carbon atoms).
[General Formula (4)]
(In the formula, R
6
is a saturated or unsaturated aliphatic hydrocarbon group of 16 to 30 carbon atoms; and m is an integer of 2 to 50).
[General Formula (5)]
(In the formula, R
7
and R
8
each is a saturated or unsaturated aliphatic hydrocarbon group of 16 to 30 carbon atoms; and n is an integer of 2 to 50).
(3) Chargeable tow as described in the above item (2), w
Fuchigami Kanemitsu
Iwata Masuo
Chiesa Richard L.
Chisso Corporation
Fay Sharpe Fagan Minnich & McKee LLP
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