Study On Bleaching Of Cooton Fabrics With Mental Complex As Catalyst At Low Temperature

The fabrics bleached with hydrogen peroxide have many advantages, such as good whiteness and whiteness stability, and hydrogen peroxide has no corrosion to equipment, small environmental pollution, being suitable for bleaching a variety of fibers and so on. However, traditional hydrogen peroxide bleaching for cotton fabrics is usually carried out at high temperature for a long time to get the desired effect, which can cause high energy consumption and serious damage to fibers. Therefore, it is a major renovation of traditional hydrogen peroxide bleaching to reduce bleaching temperature by adding catalysts which have high efficiency in catalytic activity. Schiff base metal complexes have been widely used in catalytic field due to their excellent catalytic performances; while there have been few reports about using Schiff base mental complexes as catalysts for hydrogen peroxide bleaching cotton fabrics.To build environment friendly, stable, low temperature and high efficient bleaching system, the catalytic properties of the Schiff base mental complexes for hydrogen peroxide decomposition were investigated. And the mental complexes were applied to the impregnated bleaching process and warm pad-batch bleaching process of cotton fabrics.Firstly, the catalytic properties of the Schiff base mental complexes with different ligands were investigated, and the effects of time, temperature and pH value on the decomposition of hydrogen peroxide were also discussed. The results show that the decomposition rate of hydrogen peroxide was accelerated with the extension of time, the rise of temperature and the increase of pH value. And it indicates that Schiff base metal complexes had excellent catalytic properties.Secondly, the metal complexes which were applied to impregnated bleaching process of cotton fabric were also investigated. Under the same bleaching conditions, the bleaching property was better with CuS3than that with the other Schiff base copper complexes, with CoS3than that with the other Schiff base cobalt complexes, and with MnS1than that with the other Schiff base manganese complexes. The effects of the complexes, hydrogen peroxide, pH, temperature and time on fabric whiteness were investigated by single factor experiment and orthogonal experiment. The suitable process by using CuS3as catalyst was as following:30%H2O210g/L, CuS310μmol/L, Na2SiO3lg/L, penetrating agent JFC1g/L, at70℃for60min and liquor ratio being1:20. The suitable process by using CoS3as catalyst was as following:30%H2O210g/L, CoS32μmol/L, Na2SiO31g/L, penetrating agent JFC1g/L, at70℃for60min and liquor ratio being1:20. The suitable process by using MnS1as catalyst was as following:30%H2O210g/L, MnSl15μmol/L, Na2SiO31g/L, penetrating agent JFC1g/L, treating at70℃for60min and liquor ratio being1:20. Among them, the bleaching property with CuS3was best. The whiteness of the bleached cotton fabric was67.08, capillary effect being9.6cm/30min, and breaking strength being616.2N.Finally, catalyst CuS3, activator TAED and cationic activator TBCC were applied to bleach cotton fabrics with the warm pad-batch bleaching process, respectively. The effects of the complexes, hydrogen peroxide, pH, temperature and time on fabric whiteness and breaking strength were measured. The results show that the bleaching property with cationic activator TBCC was better than that with activator TAED and Schiff base metal complex CuS3, while the dosage of CuS3was less.Schiff base mental complexes was not only beneficial to accelerating the decomposition of hydrogen peroxide and reducing bleaching temperature and the amount of alkali, but also improved the bleaching property, reduced fiber damage and realized the energy saving of cotton fabric pretreatment.