I. Overview of acid dyes
1. History of acid dyes:
In 1868, the earliest acid dye triarylmethane acid dye appeared, which had strong dyeing ability but poor fastness;
In 1877, the first acid dye acid red A for wool dyeing was synthesized and its basic structure was determined;
After 1890, the acid dye of the ruthenium structure was invented, and its chromatogram was more and more complete;
Up to now, there are hundreds of dyes in acid dyes, which are widely used in the dyeing of wool, silk, nylon and other fibers.
2. Characteristics of acid dyes:
The acidic group in the acid dye is generally based on a sulfonic acid group (-SO3H), in the form of a sodium sulfonate (-SO3Na) on the dye molecule, and some dyes are acidic with a sodium carboxylate salt (-COONa). Group.
It is characterized by good water solubility, bright color, complete chromatogram, relatively simple molecular structure compared with other dyes, lack of long conjugate coherent system in dye molecules, and low directness of dyes.
Second, acid dye classification
1. Classification according to the molecular structure of the dye precursor:
Azo (60%, extensive chromatogram)
Earthworms (20%, mainly blue and green)
Triarylmethane (10%, purple, green)
Heterocyclic (10%, red, purple)
2, according to the pH classification of the dye:
Strong acid bath acid dye: dyeing pH value 2.5-4, good light fastness, but poor wet handling, bright color, good leveling;
Weak acid bath acid dye: dyeing pH 4-5, the proportion of sulfonic acid groups in the molecular structure of the dye is slightly lower, so the water solubility is slightly worse, the wet processing fastness is better than the strong acid bath dye, and the leveling property is slightly worse.
Neutral bath acid dye: dyeing pH 6-7, the proportion of sulfonic acid groups in dye molecular structure is lower, dye solubility is low, leveling property is poor, color is not bright enough, but wet processing fastness is high.
Third, acid dye related terms
1, color fastness:
The color of the textile is resistant to various physical, chemical and biochemical effects during the dyeing and finishing process or during use and administration.
2. Standard depth:
A recognized depth standard series with a medium depth of 1/1 standard depth. The colors of the same standard depth are psychologically equal, so that the color fastness can be compared on the same basis. At present, it has developed to 6 standard depths of 2/1, 1/1, 1/3, 1/6, 1/12 and 1/25.
3. Dyeing depth:
Expressed as a percentage of dye mass to fiber mass (i.e., O.M.F.), the dye concentration will vary depending on the color.
The change in color, depth or brilliance of the dyed fabric after a certain treatment, or a combination of these changes.
After a certain treatment, the color of the dyed fabric is transferred to the adjacent lining fabric to stain the lining fabric.
6. Gray color card for assessing discoloration:
In the color fastness test, a standard gray sample card used to evaluate the degree of discoloration of a dye is generally referred to as a color-changing card.
7. Gray color card for assessing staining:
In the color fastness test, a standard gray sample card used to evaluate the degree of staining of the dyed fabric to the lining fabric is generally referred to as a stained sample card.
8. Color fastness rating:
The color fastness properties of the textile were rated according to the color fastness test, the degree of discoloration of the dyed fabric, and the degree of staining of the affixed fabric. Except for light fastness (except for AATCC standard light resistance), the rest is five-level system. The higher the number, the better the fastness.
9, lining fabric:
In the color fastness test, an undyed white fabric which is treated together with the dyed fabric in order to judge the degree of staining of the dyed fabric with respect to other fibers.
Fourth, the color fastness of acid dyes
1. Light fastness:
Also known as light fastness, the color of textiles is resistant to artificial light, and the general inspection standard is ISO105 B02;
2, washable (water immersion) color fastness:
The resistance of the color of the textile to the washing action of different conditions, such as ISO105 C01\C03\E01;
3, color fastness to rubbing:
The color resistance of textiles is resistant to friction and can be divided into dry and wet rubbing fastness.
4, color fastness to chlorine water:
Also known as the chlorine pool fastness, generally is to simulate the concentration of chlorine in the swimming pool to test the degree of chlorine resistance of the fabric, such as nylon swimsuit, the detection method such as ISO105 E03 (effective chlorine content 50ppm);
5, color fastness to perspiration:
The resistance of the color of textiles to human sweat can be divided into acid and alkali perspiration fastness according to the acidity and alkalinity of the test sweat. The dyes dyed by acid dyes generally have the basic perspiration fastness.