Patent ID: 6969409

Claim:
A modified animal fiber having a surface morphology that is substantially the same as that possessed by the fiber in its un-modified form, the modified animal fiber comprises chemically modified epidermal tissue epidermal tissue that exhibits an absorption band for â€”SO 3 H group having a relative absorbance of not less than 0.1 and an absorption band for â€”Sâ€”SO 3 Na group (Bunte salts) having a relative absorbance of not less than 0.08, when measured using reflection FT-IR having an absorption band corresponding to amide I set to 1, the epidermal tissue having epicuticle layers which afford a water repellency, confirmed by an AllwÃ¶rden reaction, that is substantially the same as that possessed by the fiber in its un-modified form, wherein the modified animal fiber exhibits shrink proofing of an area shrinkage rate of not more than 8% in a three-hour aqueous washing when measured as a felting shrinkage rate in conformity with Woolmark Test Method 31 and pilling resistance of not lower than third class in JIS L-1076.6.1A method; said modified animal fiber produced by a process which comprises: a) a first step in which a cystine â€”Sâ€”Sâ€” bond in cuticle layers on surface of the fiber is subjected to primary oxidation with an oxidizer having an ability to oxidize the â€”Sâ€”Sâ€” bond in the cuticle layers by a pad steam treatment of the modified animal fiber with an aqueous solution of oxidizing agent under acidic conditions to contain a state rich in mono-oxidized state, b) a second step in which the primary-oxidized â€”Sâ€”Sâ€” bond is subjected to an oxidation treatment with ozone being conducted by direct blowing 5 Î¼m or less ultrafine bubbles of an ozone/oxygen-mixed gas to the primary-oxidized animal fibers in an aqueous, acidic treating liquid at a pH of 1.5 to 2.5 and at a temperature of 30 to 50Â°C., into higher order oxidized state containing di, tri or tetra-oxidized state or a mixture thereof, and c) a third step in which said â€”Sâ€”Sâ€” bond in higher oxidized state is subjected to reductive cleavage.