Textile Processing
Control of metal ions is critical in several textile processing stages. Codex Phosphonates, with their excellent ability to control both hardness and heavy metal ions, should be considered in any process where metal ions interfere.
There are two critical processes where the use of phosphonate is essential: textile scouring and peroxide bleaching of textiles.
The Scouring Process :
The scouring process uses hot alkaline solutions to remove natural and other impurities from textile fabrics. If impurities are not removed, they will negatively affect subsequent bleaching, dyeing, printing or finishing operations.
Codex Phosphonates are used in scouring to remove iron and water hardness ions; this results in better fabric whiteness, prevention of staining due to iron deposits and prevention of fabric damage during bleaching caused by embedded copper or iron fragments.
- Control of Calcium in Caustic Scouring
- Codex 661
The Bleaching Process :
- Hydrogen peroxide, commonly used to bleach textiles, is easily decomposed in the presence of very low levels of heavy metals. Loss of peroxide and bleaching efficiency thus results, and in textile applications, the presence of metal particles on the fabric can cause pinholes due to the excessive rate of local decomposition of the peroxide. Very low levels of Codex Phosphonates can sequester the metal ions & prevents this decomposition.
- Also, since silicates are sometimes used in bleaching to stabilize the peroxide and buffer the solutions, the addition of phosphonates helps to prevent the scale build-up so common in silicate systems.
- Stabilization of Peroxide Bath
- Codex 4503
- Codex 5323