Basic dyes, also known as salt-based dyes. Dyes that can dissociate into cationic pigments in aqueous solution are classified as cationic dyes. Since basic dyes have poor light fastness and washing fastness after dyeing fibers, they are now rarely used for dyeing fabrics and are mainly used for coloring cultural and educational supplies, paper and manufacturing lakes.
Most of the chromophoric groups of basic dyes are organic bases, and a few of the salts (chlorides) formed with inorganic acids are other salts. When the dye dissociates in an aqueous solution, the pigment group is positively charged, so it is a cationic dye. It is characterized by bright color, magnificent fluorescence (mainly rose red, yellow, orange and other colors), and strong tinting power. A very small amount of dye can be used to obtain a deep and rich color. The color fastness and light fastness are poor, but it has good fastness when used on acrylic fiber (polyacrylonitrile fiber). Basic dyes do not color cellulose fibers. In the early 1970s, my country adopted the grafting method to dye silk with cationic dyes.
After this type of dye is ionized, the dye ions become positively charged and can combine with acidic substances to form salts. Commonly used basic dyes in microbiology laboratories include methylene blue, methyl violet, ammonium oxalate crystal violet, acetic magenta, basic fuchsin, neutral red, malachite green, and fuchsia. Under normal circumstances, bacteria are easily Dyeing with basic dyes.
Common basic dyes include: basic brilliant green (green 1), basic magenta green (green 4), basic rhodium B (purple 10), basic royal blue, basic violet 5BN (purple 3), alkali Basic orange block (orange 2), basic magenta (purple 14), basic bright yellow O (yellow 2), basic brown G (brown 1), basic brilliant blue BO (blue 7), basic blue G ( Blue 1), alkaline blue B (blue 5), alkaline lake blue BB (blue 9), alkaline red (alkaline national flag red), alkaline black, alkaline dark green, alkaline brilliant blue, etc.