Phthalimide disperse dyes are sensitive to alkali and can be hydrolyzed into water-soluble dyes under weak alkaline conditions. Advantages in dye application process:
(1) Hydrolyzed dyes have low affinity for polyester, which is easy to wash off in the process of washing after dyeing. In the color fastness test, dyes have low affinity for multi-fiber fabrics, showing high color fastness to washing. Disperse dyes commonly used in dyeing polyester/polyurethane elastic fabrics, fine denier polyester fabrics and multicolor spliced polyester fabrics are difficult to dye with high color fastness to washing, because phthalimide disperse dyes have the above properties and can be used as disperse dyes with high color fastness to washing to dye polyester/polyurethane elastic fabrics.
(2) After dyeing the polyester fabric, only the alkali washing process is used, which avoids the decomposition of azo group to produce carcinogenic aromatic amine under the condition of sodium hydrosulfite reduction cleaning, which can effectively reduce BOD in sewage and reduce the burden of washing sewage treatment.
In this experiment, six phthalimide disperse dyes were used as the main body in imine manufacturers to study the dyeing properties of polyester fabrics with different structures of disperse dyes under different pH dyeing conditions and the absorbance curves in sodium hydroxide solution at different dissolution temperatures (40, 60, 80℃). The formation of dicarboxylic acid structure in hydrolyzed dyes was analyzed by infrared spectroscopy, and the hydrolysis mechanism of dyes was analyzed by high performance liquid chromatography.
The electron cloud density was calculated by density functional theory B3LYP/6-311++G(d, P), and the relationship between structure and hydrolysis performance of phthalimide disperse dyes was studied by comparing K /S values under different pH conditions. And finally draw a conclusion
(1)pH has obvious influence on the dye uptake of phthalimide disperse dyes. With the increase of pH, the dye in the dyeing bath is hydrolyzed seriously, and the imide group is hydrolyzed into carboxyl group, which increases the water solubility of the dye, reduces the affinity of the dye to polyester and reduces the dye uptake on polyester fabric.
(2) In NaOH alkaline solution, with the increase of temperature, the absorbance of dye at absorption wavelength gradually increases, which indicates that the five-membered ring of dye phthalimide group is hydrolyzed to form carboxyl under alkaline condition, and the amount of dye dissolved in alkali liquor increases.
(3) High performance liquid chromatography showed that ethyl substituted dyes were completely hydrolyzed within 30 min. With the increase of substituents, the hydrolysis rate of dyes increased.
The above is the relationship between the structure and hydrolysis performance of N-alkyl phthalimide disperse dyes introduced by Huai 'an imine manufacturer, hoping to help everyone!