Carbonless copy paper (NCR paper) consists of upper paper (CB), medium paper (CFB), and lower paper (CF). The back side of the upper paper is coated with a coloring agent, the front side of the medium paper is coated with a color developing agent, the back side is coated with a coloring agent, and the front side of the lower paper is coated with a color developing agent. NCR paper can be divided into black printing paper, blue printing paper or other color printing paper according to the color type. At present, the more common NCR paper color is blue. NCR paper is used for printers because it does not require carbon copy paper. It is clean and convenient. NCR paper is a high-tech product, and as the amount of the product increases, its quality requirements are also higher. Here, the author will share the reasons and solutions for blue dot paper disease on the CF surface of the paper.
Color development mechanism of NCR paper.
The color development mechanism of NCR paper is that after the paper, medium paper and lower paper are normally matched (the medium paper can be connected or multi-joined), when used, the pressure from the outside (such as the nib, printer, etc.) makes the back of the CB paper. The microcapsules are broken, and the contained mixed dye flows out and reacts with the developer on the CF surface to develop color.
Causes and solutions for blue dot paper disease.
The blue dot quality paper disease of NCR paper generally occurs on the CF side of medium paper. There are many factors that cause the blue dot on the CF surface of the medium paper. We can analyze the reason, cause and method of the blue dot on the paper surface.
(1) At the time of initial coiling, if blue paper disease occurs due to friction between papers due to the difference in the speed of the take-up, the shape is generally elongated, and the increase in the take-up tension during winding can solve or alleviate this.
(2) At the time of coating, the paint splashed from both sides of the paper web to the CF side of the paper, and after drying, it was pressed to generate a blue dot. It is caused by unreasonable adjustment of the angle of the air knife, which generally occurs on both sides of the paper web. The solution is to adjust the angle of the air knife and install a baffle on the lower side of the return roller to prevent the paint from splashing onto the CF surface.
(3) During the coating process, the blue dot produced by the embossing during winding is caused by the excessive moisture content entering the dryer coated paper.Although reducing the moisture content can solve this paper disease, it will reduce the smoothness of the CB surface and thus affect the quality. The solution is to add a scraper to the dryer.
(4) The microcapsules in the fixed position of the medium paper are displaced and ruptured, and the mixed dye flows out, and a blue dot is generated on the CF surface through the base paper. This blue dot is generally sparsely dispersed and has a small shape and is associated with excessive shrinkage of the base paper. In addition, pinholes in the base paper will also cause blue dots.This kind of blue dot caused by the quality problem of the base paper is preferably replaced with the base paper used.
(5) The quality of the microcapsules is problematic, and the mixed dye penetrates into the CF surface during the coating process to produce a blue dot. This blue dot usually fills the entire page, the color is brighter, and the shape is inconsistent.This blue dot paper disease is related to the quality of the capsule, mainly because the capsule contains a free mixed dye that penetrates into the CF surface to produce a blue dot.