Down is a natural protein fiber. Down products are soft, lofty and have excellent thermal properties. The products are deeply loved by consumers.
Down can be used as stuffing for sporting goods, handicrafts, clothing and bedding, and has important economic value. Among them, down processing ranks first as a filler for clothing and bedding.
Down can be divided into pure white down and different color down as clothing and bedding.
Among them, gray down and other different-colored down are not widely used and the price is cheap. This part of feathers is reprocessed to increase its application value, which has good economic benefits. Therefore, research on the bleaching technology of colored down is of great significance for increasing the added value of different colored down and increasing the export of white feathers for down manufacturers.
Common gray down and depigmentation can be treated with oxidizing and reducing agents. These two methods are not mature and effective enough, and there are many problems in bleaching down products. Decolorized and bleached down feels firmer and less bulky.
However, if only H2O2 is used as an oxidant to carry out oxidative bleaching, the bleaching process is difficult to control, and it is easy to cause excessive or incomplete oxidation, and it is easy to cause down to become brittle and easy to change color. After a period of time, usually about three months, the bleached down part will change color, seriously affecting the performance of the bleached down. It is reported that down fabrics are bleached through selective oxidation bleaching combined with reduction bleaching.
In addition, some scholars have carried out selective bleaching research on ostrich hair and yak hair.
Aiming at the technical difficulties of bleaching colored down, Shijiazhuang Down Manufacturer has developed a low-temperature selective bleaching process for colored down through systematic research on pretreatment (metal complexation) and cleaning bleaching technology, which solves the contradiction between whiteness and fiber brittleness, and achieves good result.
Material: gray down
Chemicals: Sodium Hypophosphite; Sodium Pyrophosphate; Ferrous Sulfate; Sodium Hydroxide; Formic Acid; Glacial Acetic Acid; Hydrogen Peroxide 30%; Detergent 209 Industrial Product; Ammonia.
Instruments: DHG-9070A electric heating constant temperature blast drying oven; DSHZ-300A rotary constant temperature oscillator; SHZ-D circulating water vacuum pump; WSD-3V fluorescent whiteness meter.
The selective bleaching process is divided into three steps: pretreatment, cleaning (water washing or auxiliary cleaning) and hydrogen peroxide bleaching.
Pretreatment is to complex the colored down with a suitable pigment complexing agent, and carry out the corresponding complexation treatment process, so that the metal ion of the complexing agent and the pigment form a complex.
In the subsequent H2O2 bleaching process, metal ions will act as catalysts to selectively carry out H2O2 bleaching, effectively catalyzing and bleaching the pigments in the colored down.
Since down is naturally water-repellent, JFC is added as a wetting agent during pretreatment. In order to minimize the oxidation of ferrous ions and the loss of down fibers, please put the down fibers and treatment solution in a sealed plastic bag.
Washing is an intermediate process between pretreatment and selective bleaching, and plays a very important role in the selective bleaching effect. If the cleaning is not sufficient, the metal ions adsorbed on the down fiber keratin cannot be cleaned. During the bleaching process, it catalyzes the bleaching of down keratin, severely damaging down fibers and making them brittle.
If the cleaning power is too strong, the metal ions complexed on the pigment will also be separated from the complex, losing the effect of selective bleaching, and the whiteness will deteriorate. Since down is easy to lose during washing, in this experiment, the beaker was covered with breathable fabric for washing.