General Properties of Disperse Dyes

1
General Properties of Disperse Dyes
2
Introduction

• Disperse dyes are a class of nonionic dyes that
  are present in a highly dispersed state in water.
  Disperse dyes are the only water-insoluble dyes
  for the dyeing of polyesters and acetates. And
  they are also used as colorants in the
  manufacture of "ironing" transfer crayons and
  inks. The article introduces some general
  properties of disperse dyes.

3
Appearance

• The appearance of disperse dyes can be divided in
  to three types power dye, granular dye and
  liquid dye. Generally, the powdery disperse dyes,
  such as disperse yellow 163 and disperse red 277,
  contain a dustproofing agent, so the powder is
  fine but does not fly like dust. Granular
  disperse dyes are produced by commercial
  processing using new granulation and drying
  technology. When the granular dye is weighed,
  there is no flying dust, but the volume of the
  product is larger. The liquid dye used for
  padding or printing does not settle evenly, the
  dispersant content is small and the color is deep.

4
Color shade

• The shade of the dye refers to the color and
  brightness of the dyed textile fiber.
  Commercially, shade is an important indicator of
  dye properties and evaluation of dye quality. For
  the applications of dyes, control of the shade of
  dyes is an important guarantee for the quality of
  dyed products. The color shade of a qualified
  commercial dye must be consistent with the
  standard under the same dyeing conditions. The
  color shade of the disperse dye is determined by
  its structure, but it is also related to the
  synthetic route of the dye. Dyes of the same
  structure often have different shades due to
  their different manufacturing processes. The
  shades of the same dye dyed on polyester and the
  shades dyed on vinegar, nylon, acrylic or other
  synthetic fibers are the same or different.
  Therefore, the same fiber material must be used
  when selecting dyes and comparing dye shades. The
  brightness of disperse dyes varies from species
  to species. Dyes with higher brightness usually
  add "Billi" or "Light" to the name of the dye
  product to show the difference. Fluorescent
  disperse dyes are limited to yellow, orange, and
  red.

5
Solubility

• The solubility of disperse dyes in water is very
  low, about 0.1 32 mg / liter in cold water and
  about 0.2 100 mg / liter in hot water at 80?.
  Heated the water till the temperature rises to
  130? in a pressure vessel, solubility can up to
  200 mg / liter. The solubility of the dye is
  strongly influenced by the temperature and
  related to the structure and molecular weight of
  the dye. Commercial disperse dyes usually contain
  more anionic dispersing agents, which have a
  significant solubilizing effect on disperse dyes.
  When preparing dyeing solutions, most of the dyes
  that can be dissolved in water are various
  dispersants, and the fine dye particles are
  surrounded by the water-soluble dispersant. The
  dye solution of the disperse dye is not actually
  a solution. This incompletely dissolved liquid is
  called a dispersion.

6
PH Sensitivity

• Disperse dyes have many varieties and wide
  chromatograms, and the sensitivity to sulfuric
  acid is very inconsistent. Dyeing liquids with
  different pH values often lead to different
  dyeing results, affecting the color depth, and
  even causing color change. In a weakly acidic
  medium (pH 4.5 to 5.5), the disperse dye is in
  the most stable state. The pH of the disperse dye
  solution varies, some are neutral and some are
  slightly alkaline. Before the dyeing, it should
  be adjust to the specified pH with acetic acid.
  During the dyeing process, the pH of the dyeing
  solution is sometimes gradually increased, and if
  necessary, formic acid and ammonium sulfate may
  be added to keep the dyeing solution in a weakly
  acidic state. Some disperse dyes with the azo
  structure are very sensitive to alkali and are
  not resistant to reduction. Disperse dyes with
  ester groups, cyano groups or amide groups are
  mostly affected by alkali hydrolysis to affect
  their normal shade.