Pressure sensitive recording paper and thermal recording paper
In the field of information industry paper, most of the paper currently used is invented according to the needs of various information output and input systems, and its scope covers all processes of participation in information production to information circulation, in which business forms are duplicated. Electronic communication, image communication, etc. are the main medium for input and output of information. As the technology and use of paper for the information industry is expanding to the fields of fax and electronic computer output printing, the rapid development of technology and production of pressure sensitive recording paper and thermal recording paper has been promoted. According to the technology forecast survey, the most used type of recording paper is microencapsulated carbonless copy paper type pressure sensitive recording paper, which can be copied 7-8 pages at a time. If the number of copies is to be further increased, it is necessary to reduce the amount of paper, but it must address a series of low-quantity base paper production, microcapsules, color formers, and coating processing technical problem. The demand for carbonless copy paper and thermal recording paper will increase accordingly.
In carbonless copy paper and thermosensitive recording paper, leuco dye is used as a coupler. When it reacts with an “acidic” developer, a unique color is produced, the coupler is an electron donor, and the developer is an electron acceptor.
Different colors of leuco dyes
The image quality of carbonless copy paper and thermal recording paper is very important. Its image speed, hue, sharpness, density, light resistance, etc. mainly depend on the quality of the coupler and color-developing. From a certain perspective, couplers are more decisive for these properties, so many different colors of leuco dyes are available on the international market. The product quality is high and the variety is wide. The earliest used leuco dyes are alkaline malachite green and alkaline fragrant red-B-endoleamine, which are eliminated due to their low sensitivity and poor color.
Crystal violet lactone and blue leuco dye
Crystal violet lactone (CVL) is an internal derivative of triphenylmethane dye. It is the most widely used blue leuco dye. The light stability of CVL reacts with phenol resin after color reaction. The light after CVL reacts with activated clay developer poor stability, CVL is generally used with BLM (BN-benzoquinone colorless methylene blue) and used in clay CB coating.