With the development of modern science and technology, the printer, copier and fax machine have become the necessary "three big parts" in the office. Thermal paper
, as "special paper", is widely used in supermarkets, Banks, hospitals, airports and other places. Once had the netizen question this kind of small note, and the ordinary printing has any difference? How is the text printed? Why does it disappear over time?
Thermal paper is also known as thermal fax paper, thermal recording paper, thermal copy paper, is called thermal carbon paper in Taiwan. Thermal paper is a kind of processing paper, its manufacturing principle is in the quality of the base paper coated with a layer of "thermal coating" (thermosensitive layer). Although there are more than a dozen chemicals used in this layer, there are at least the following compounds: colorless dyes. Color reagent accounts for about 20% of the following, commonly used bisphenol, p-hydroxybenzoic acid; Sensitizing agent accounts for less than 10%, which contains benzene sulfonate amide compounds; About 50% of the filler, commonly used calcium carbonate (particles); Adhesive about 10% or less, such as polyvinyl acetate; Stabilizers, such as terephthalic acid diphenyl; Lubricants, etc. Therefore, the process is difficult, high technical requirements.
There are mainly two kinds of thermal-sensitive components in thermal paper: one is a colorless dye or called cryptochrome dye; The other is a colorant. Thermal paper mix the colorless dye and colorant chemical reaction to produce color, so the use of heat sensitive paper in the fax machine to receive a signal to print or print directly with the heat sensitive printer, graphics and text will be displayed. As there are many varieties used as colorless dyes, the color of the handwriting is different, including blue, Burgundy, black and so on.
However, under the condition of heat, the film melts and the powder is mixed for color reaction. The color developing handwriting on the thermal paper is unstable and easy to fade, leading to the illegibility of the document content. This is why some shopping receipts fade over time.
Ordinary thermal paper is not suitable for long-term preservation, but good thermal paper can be stored for 30 years or longer.
Distinguish true and false
Thermal paper is often used in lottery tickets, tickets and other valuable tickets, formal tickets are used in high-tech thermal paper, the ticket surface is relatively smooth, uniform color, clear writing, no obvious color difference, with a nail on the ticket surface can draw black scratches, counterfeit tickets using ordinary coated paper is no trace.
When we have to choice, pay attention to if uneven thermal paper coating, will lead to print, in some places darker, some local color shallow, significantly lower print quality, if the thermal coating of chemical formula is unreasonable, can cause printing paper to save time become very short, good printing paper after printing can save (under the condition of normal temperature and avoid direct sunlight) five years, are now more long-term thermal paper can save ten years, but if the thermal coating formula is not reasonable, may be only a few months.