Carbonless copy paper

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Carbonless copy paper or NCR paper is an alternative to carbon paper, used to make a copy of an original, handwritten document without the use of any electronics. The process was co-invented by chemists, Lowell Schleicher and Barry Green, working for the NCR Corporation as a biodegradable, stain-free alternative to carbon paper.^[1]

1 Operation
2 Dyes and chemicals
3 References
4 External links

[edit] Operation

Carbonless copy paper works in a fairly simple way. It consists of sheets of paper that are coated on the bottom and/or the top with micro-encapsulated dye or ink and/or a reactive clay.

The back of the first sheet is coated with micro-encapsulated dye. The top of the middle sheet is coated with a clay that quickly reacts with the dye to form a permanent mark. The back of the middle sheet is also coated with the dye. The lowermost sheet is coated on the top surface with the clay with no coating applied to the back side.

When someone writes on the sheets, the pressure from the point of the writing instrument causes the micro-capsules to break and spill their dye. Since the capsules are so small, the print obtained is very accurate.

Around fifteen pages can be copied using one sheet of carbonless copy paper.

Carbonless copy paper was also available in a self-contained version that had both the ink & the clay on the same side of the paper.

[edit] Dyes and chemicals

The first dye used commercially in this application was crystal violet lactone, which is still widely used today. Other dyes and supporting chemicals used are PTSMH (p-toluene sulfinate of Michler's hydrol), TMA (trimellitic anhydride), phenol-formaldehyde resins, azo dyes, DIPN (diisopropyl naphtalenes), formaldehyde isocyanates, hydrocarbon-based solvents, polycyclic aromatic hydrocarbons, polyoxypropylene diamine, epoxy resins, aliphatic isocyanates, Bisphenol A, diethylene triamine, and others.

The dyes in carbonless copy papers may cause contact dermatitis in sensitive persons.