Electrically conducting fiber and method of making same

Details

Inventors: Tomibe, Shinji; Gomibuchi, Reizo; Takahashi, Kiyofumi;
Assignee: Nihon Sanmo Dyeing Co., Ltd. (Kyoto, JP)
Primary Examiner: Smith; John D.
Assistant Examiner: Bueker; Richard
Attorney, Agent or Firm: Fisher, Christen & Sabol

Electrically conducting acrylic and modacrylic fibers are prepared by subjecting the fibers to a first heat-treatment in a bath containing a copper compound and a reducing agent to adsorb monovalent copper ions within the fibers. The heat-treated fibers are washed thoroughly and then subjected to a second heat-treatment in the presence of a sulfur-containing compound to convert the adsorbed monovalent copper ions to copper sulfide. The electrically conducting fibers have superior conductivity which is not lost in repeated washings. The electrically conductive fibers can be dyed readily with cationic dyes without loss of electrical conductivity. The electrically conductive fibers of the present invention possess the touch and other physical characteristics of the starting acrylic or modacrylic fibers.

DETAILED DESCRIPTION OF THE INVENTION In the first stage of the process of the present invention, the acrylic or acrylic-series fibers, including modacrylic fibers, are heat-treated in a bath containing a copper compound and a reducing agent at a temperature of from about 90.
degree.
C.
to about 110.
degree.
C.
so that monovalent copper ions are absorbed by the fibers.
The bath can optionally contain an acid or an acid salt for adjusting the pH of the bath.
Suitable acids and salts for this purpose are sulfuric acid, hydrochloric acid, and salts thereof.
Suitable pH values are in the range of from about 1.
5 to about 2.
0.
Suitable copper compounds which provide monovalent copper ions for adsorption by the fibers are cupric salts, such as cupric sulfate, cupric chloride, and the like and chelate compounds of copper, and the like.
Suitable reducing agents for inclusion in the bath are metallic copper, hydroxylamine, ferrous sulfate, ammonium vanadate, furfural, and the like.
The bath temperature is preferably in the range from 90.
degree.
C.
to 110.
degree.
C.
so as to efficiently adsorb the monovalent copper ions and to maintain the strength of the fibers.
At temperatures below 90.
degree.
C.
, it takes many hours for the adsorption process.
At temperatures over 110.
degree.
C.
, the strength of the fibers drops.
The greater the quantity of copper ions adsorbed by the fiber, the better the electrical conductivity of the product fibers.
However, if the copper ion content is too high physical properties, such as fiber strength, are reduced.
On the other hand, satisfactory electrical conductivity properties cannot be obtained at very low copper ion contents.
In the practice of the present invention, the amount of monovalent copper ions to be adsorbed by the fiber should be from 1 to 30% by weight (expressed in terms of the weight of metallic copper) based upon the weight of the starting fiber.
In the first stage of the process of the present invention, the acrylic or acrylic-series fibers having adsorbed monovalent copper ions become yellowish

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