Paper industries is one of the oldest industries in which extensive use of various dyes have been done since ages. People have found many kinds of dyes which can be used in many ways to create various varieties of papers. With time and development of science and technology scientists have found many techniques for bulk production of various dyes which can be easily used in dying papers.

Word paper is not limited to a sheet of paper used for righting or drawing purpose. There are many variations in the kind of papers produced in paper industry such as writing and printing paper, tissues used as toilet paper, facial tissues or used as paper napkins or towel, copier paper, cover papers, corrugated papers used for packing, handmade paper, lamination paper and the list is endless. For each kind of paper different kind of dye is required. This entire calculation projects a great scope for dyes in paper industry.

Classification of dyes used in paper industry!

Out of large varieties of dyes available in the market, dyes can be broadly classified into sulphur dyes and cationic dyes. Both kinds of dyes differ in their molecular structure, their mode of operation and their reaction to various chemicals. Depending on the kind of paper to be dyed, selection of either of the two dyes is done. The above two dyes are the most popularly used dyes in the paper industry. Apart from that acidic dyes and basic dyes are also used in paper industry.

Factors affecting selection of dyes!

There are many criteria on which selection of the Basic dyes for paper dying can depend. Some of them are discussed below:

• Dye under consideration should have optimum depth for proper printing.
• The dye should have good affinity in order to properly stick and stay on the paper.
• Right colour shade is one of the important criterions for dye selection.
• Apart from that dye should also display qualities like light fastness and bleed fastness.
• Dye should exhibit high stability for temperature and humidity and it should have low or almost no metamerism.
• Dye should not interfere with any other parameter or process of paper manufacturing.
• It should be safe in use and comply with government standards and regulations.

Changing trends in dyes!

With increasing environmental awareness and pressure from various government and non government organisations, paper industry is shifting towards increased use of eco friendly dyes. Scientists are working hard for creating dyes with low amine content which do not have any hard effect on both the user and environment. Use of heavy metals in manufacturing of dyes is also discouraged in the present times. Apart from that popularity of natural or organic dyes is also increasing in paper industry. These Direct dyes are prepared from bio degradable material which leads to low pollution at the time of producing dyes and also at the time of its usage in paper industry. Bulk production of these dyes at low cost is the soul motive of the people in industry.