happoväriaineita

Happoväriaineita, known in English as acid dyes, are a class of anionic dyes that are applied to textiles from an acidic dyebath. These dyes are typically water-soluble and are characterized by the presence of acidic functional groups, such as sulfonic acid groups. Their affinity is primarily for fibers that contain basic functional groups, making them particularly effective for dyeing protein fibers like wool and silk, as well as polyamide (nylon) fibers.

The dyeing process for acid dyes involves a chemical reaction between the acidic dye molecule and the basic sites on the fiber. The acidic dyebath, usually maintained at a pH between 2 and 6, promotes the protonation of basic groups in the fiber, creating positively charged sites. The anionic dye molecules are then attracted to these positive sites through electrostatic interactions. Temperature is also a crucial factor, with higher temperatures generally leading to faster dye uptake and deeper shades.

Acid dyes are available in a wide spectrum of colors and exhibit good lightfastness and washfastness on suitable fibers. They are used extensively in the textile industry for dyeing clothing, carpets, and upholstery. Beyond textiles, some acid dyes find applications in coloring paper, leather, and even certain food products, though specific regulations govern their use in the latter. The classification of acid dyes can vary, with some being categorized as leveling, milling, or supermilling dyes, reflecting differences in their molecular structure and dyeing properties.