Carbonless copy paper is divided into upper page or CB paper (Coated BackPaper), middle page or CFB paper (Coated Front & BackPaper) and lower page or CF paper (Coated Front Paper).
Common components of CB coatings and their performance requirements:
CB coatings are mainly composed of chromogenic agent microcapsules, spacers, adhesives, additives and water.
1. Microcapsules are the most important component of CB coatings. The quality and dosage of microcapsules are closely related to the color development of carbonless copy paper. The solid content of microcapsules is generally 40% to 50%, mainly composed of colorless dye oil, wall materials and Emulsifier composition. The quality of microcapsules mainly affects the color rendering effect, light fastness, and pollution of carbonless copy paper.
2. The use of spacers in CB coatings is to prevent premature rupture of microcapsules under the influence of external forces during the batching and coating process. Wheat starch is currently the most widely used spacer in CB coatings. The main quality index of the spacer is the size of the particle size. It is generally required that the spacer with a particle size in the range of 15-25 μm should account for 60-80%, and the particle size should not be greater than 40 μm. The amount of spacer is generally 30% to 50% of the amount of microcapsules (dry ratio). The larger the particle size of the microcapsules or the weaker the strength of the microcapsules, the more spacer is needed.
3. There are generally two types of adhesives used in CB coatings, one is carboxylated styrene-butadiene latex and the other is modified starch. There are also a few manufacturers who use polyvinyl alcohol (PVA) with modified starch. Among them, the amount of carboxylated styrene-butadiene latex is generally 3% to 4% (for paint, dry ratio), and the amount of modified starch is generally 10% to 12% (for paint, dry ratio).
4. The additives used in CB coatings include dispersants, sodium carboxymethylcellulose (CMC) and preservatives. The dispersant is sodium polyacrylate, the dosage is generally 0.2% to 0.3% (for paint, dry ratio), and the dosage of sodium carboxymethylcellulose (CMC) is generally 0.5% to 1.5% ( For coatings and dry ratio), it can be adjusted according to the viscosity requirements of the coating. The amount of preservatives is generally 0.5% (to starch, dry ratio).
Common components of CF coatings and their performance requirements:
CF coatings are mainly composed of pigments, color developers, adhesives, additives and water.
1. The purpose of using coating pigments on carbonless copy paper is to fill and cover the uneven surface of the base paper, improve the whiteness and opacity of the paper, improve the smoothness and gloss of the paper surface, and make the surface of the paper have uniform and good ink Absorbency, finally get a good printing effect. The main pigments used in CF coatings are kaolin and calcium carbonate.
2. The color developer used in CF coatings is mainly phenolic resin, and a small amount of zinc salicylate is used together with it. The main purpose of using zinc salicylate is to improve the color development speed of carbon-free paper, especially at low temperature. . The amount of color developer generally accounts for 11% to 13% of the total paint (dry ratio), while the ratio of phenolic resin to zinc salicylate is generally 10:1 (dry ratio), the addition of zinc salicylate The amount should not be too much, otherwise it will increase the pollution of the paper.
3. There are generally two types of adhesives used in CF coatings, one is carboxylated styrene-butadiene latex and the other is modified starch. Among them, the amount of carboxylated styrene-butadiene latex is generally 4% to 5% (for paint, dry ratio), and the amount of modified starch is generally 12% to 14% (for paint, dry ratio).
4. The additives used in CF coatings include dispersants, sodium carboxymethyl cellulose, foam inhibitors, lubricants, preservatives and caustic soda. In addition, when producing colored paper, the pigments added to the paint include red powder, yellow powder, emerald blue and emerald green, and the corresponding colors of carbonless copy paper produced are red, yellow, blue and green.
Post time: Apr-03-2023