Chemical Functional Definitions
Dye Transfer Inhibitors: Poly(N-vinylpyrrolidone) and Poly(vinylpyridine N-oxide)
Shorthand notations
Dye transfer inhibitor = DTI
Poly(N-vinylpyrrolidone) = PVP
Poly(vinylpyridine N-oxide) = PVP-NO<
Poly(N-vinylpyrrolidone) = PVP
Poly(vinylpyridine N-oxide) = PVP-NO<
What is a DTI?
A DTI is pretty much what the name suggests: a substance that prevents the transfer of dyes from one garment to another in the wash. Today's multicolored (often brightly colored) fabric loads put high demands on the laundry detergent. It would not be practical to do laundry in batches of similar colors. We are willing to separate out our whites and our "hot" loads, but as for the colors we want to put them all together! In the wash, dye molecules leach out of the garments - this is also called "bleeding" - and the extent to which this happens depends on newness of the garment, type of fabric, type of dye and wash conditions. The surfactants in the wash often contribute to this "bleeding" phenomenon. If such free dye molecules were to redeposit themselves randomly on other garments, pretty soon our brights would no longer be so bright. Bleach cannot offer a solution in this case, because it would attack the dye molecules in solution as well as the dye molecules on the fabric, causing "bleach stains". This is where DTIs come in: they act as dye scavengers!
How do DTIs work and how are they used?
DTIs bind irreversibly to free dye molecules in the wash water and form water-soluble macromolecules. This way, the dyes are prevented from redepositing onto garments and are removed with the spent wash water. DTIs may be added up to 0.5% (w/w) to powder specialty detergents for delicate and colored fabrics. Such products are usually marketed as "color care" detergents; typically these do not contain bleach nor optical brighteners (fluorescent whitening agents or FWAs); they were first introduced on European markets in 1991.
Not all DTIs work for all dyes. Certain combinations work better than others, depending on the chemical structures of the dye and the DTI. The most commonly used DTIs in laundry detergents are PVP and PVP-NO.
Not all DTIs work for all dyes. Certain combinations work better than others, depending on the chemical structures of the dye and the DTI. The most commonly used DTIs in laundry detergents are PVP and PVP-NO.
More information about the use of polymers in modern and future laundry detergents<
- Carrier, A. M. 1994. Future Directions for Water Soluble Polymers in Detergent Applications. Presentation by Alco Chemical, Chattanooga, TN, USA. Presented at the 85th AOCS annual meeting.
- Laundry Detergents. E. Smulders (Ed.). Wiley-VCH Verlag GmbH, Weinheim, Germany, 2002. ISBN 3-527-30520-3.
- Venegas, Manuel G. 1998. "Detergency Mechanisms" in Powdered Detergents, Schick M.J. and Fowkes F.M. (Eds.), Marcel Dekker, Inc. New York.
