contact for fd&c red 40 fd&c red 40 by Standardcon

Application of Dyes and Pigments
Paper Industry

Perfect Dyeing of Laminated Paper

Approximately 70% of Diresul Black for paper production goes to laminated paper are dyed using sulphur dyes. The laminated paper must show good resistance to humidity, show high absorbtion, high lighfastness and resistantance to heat. The paper is padded up in resin solutions (generally melamine or urea resins), and is dried at temperatures between 110 and 1700 C, by applying high pressure. A Perfect recipe for dyeing consists of mixing in right proportions of :-
  • Pulp (Long and short fiber)
  • Fillers
  • Sulphur Dye
  • Hydrogen peroxide
  • Alumina
  • Sodium aluminate
Over the years Paper makers have used dyes. Seeing the growth in the paper industry it can be safely assumed that Dyes for paper industry has a very promising future. Given below is a comprehensive list of the various grades of paper that are open to dyeing.
  • Writing and printing paper
  • Tissue - Facial, toilet, towel, napkin
  • Copier papers
  • Boards/Cover papers
  • Decorative laminated paper
  • Packaging grades - corrugated case stuff
  • Envelope grades
  • Specialty papers like, label, laundry tag, posters
The dyes that are used includes sulphur dyes and cationic direct dyes. Other than these two popular options acid dyes and basic dyes are also used. Sulphur dyes are reduced alkaline solutions. For example to get the colour black, a polymer is obtained by the result of a reaction between. 2, 4 dinitrophenol and sodium polysulphide. The polymer structure is shown below.

Sulphur Dye

Coming to the Cationic Direct Dye, some features which makes them suitable towards use in paper are:
  • An extended conjugation
  • A planar molecular structure
  • An excess of positive charge over the negatively charged surface groups
A typical structure of a cationic direct dye is given here.
Cationic direct dye

Criteria for selection of the Dye

To give a stable paper, the dye selected must give:
  • Right shade
  • Optimum depth
  • Clear backwaters
  • Good affinity
  • Show light fastness
  • Show bleed fastness
  • Provides stability to temperature and humidity
  • Low or no metamerism
  • Compliant with regulations in force
  • Safety in Handling
  • Does not affect any other paper chemical/process or parameters
New Trends appearing in paper dyeing

  • Sophisticated high speed machines are driving the trend of reduction in the use of traditional basic dyes and increasingly giving way to specialty modified Basic and Direct Dyes.
  • Trend towards new colouration techniques fuelled by pressures of a clearer backwater, pressures from environmental watch dogs and cost of production.
  • A definite shift to continuous dyeing/size press dyeing.
  • Newer opportunities propelling new applications like Carbonless papers/Thermal Papers.
  • Turn to Eco-friendly dyes
    • Dyes that are free of harmful amines.
    • Dyes that are free of Heavy Metals.
    • Certification from ETAD (Ecological and Toxicological Association of dyestuff).
    • Dyes that are Biodegradable.


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