Patent ID: 8486225

Claim:
A bleached fiber product production method for bleaching a fiber product mainly including at least one of a natural fiber and a regenerated fiber to produce a bleached fiber product, the method comprising the steps of: loading the fiber product into a lidded hermetic vessel serving as a treatment vessel; forcibly circulating a treatment liquid in contact with the fiber product loaded in the treatment vessel through a forcible circulation pipe attached to the treatment vessel and provided with a circulation pump to thereby wet the fiber product; supplying an ozone gas into the treatment liquid in a minute bubble form via a gas-liquid mixing/ejecting means, the gas-liquid mixing/ejecting means being selected from an ejector, a vortex pump and a mixing pump, to provide an ozone-containing liquid, and forcibly circulating the ozone-containing liquid in contact with the wetted fiber product through the forcible circulation pipe to thereby bleach the fiber product; forcibly circulating an ozone decomposing chemical agent liquid in contact with the bleached fiber product through the forcible circulation pipe to thereby decompose ozone; and rinsing the fiber product after the decomposition of the ozone; wherein an ozone concentration in the treatment vessel is measured over time in the fiber product bleaching step, and maintained within a predetermined range by increasing an ozone gas supply amount if the measured concentration is lower than a predetermined range, and reducing the ozone gas supply amount if the measured concentration is higher than the predetermined range.