Effect of secondary coating on the performance of matte color inkjet paper

First, the development status of matt color ink jet printing paper

With the rapid development of computer technology, digital imaging technology and network technology, the rapid spread of computers, the increasing degree of office automation, and the significant increase in sales of digital cameras and camera phones, inkjet printing technology as a special printing Its non-contact, low noise, high speed, low cost, good quality, size-free, environmental protection and other advantages have been widely used. With the continuous development of the color inkjet printer market, its main consumables - color inkjet printing paper (also known as color spraying paper) is also increasingly attracting the attention of users. At present, the production of matte and matte coated paper in western Europe accounts for about 50% of the coated paper market, and in the United States, matte paper also accounts for 20% of the output of coated printing paper. In the North American market, this trend also occurs. Continue to grow. The matte coated paper and matte coated paper have become an important part of the coated paper market due to their low paper gloss and high print gloss, excellent printability and readability. At present, the domestic use of glossy inkjet paper is basically imported and the price is relatively high. Therefore, there is an urgent need for high quality and low cost inkjet paper to replace imported products from abroad.

However, the production of matte and matte coated papers is mainly achieved through the combination of different performance pigments to achieve a lower sheet gloss. This combination of pigments requires both the reduction of sheet gloss and the production of a high-quality paper print surface. One or two pigments are difficult to meet, often using a variety of pigments with different properties, sometimes up to five. , The production is extremely inconvenient and the cost is high.

To reduce costs, it is necessary to change the paint formulation of coated paper and use a reasonable coating method without reducing the performance of the paper.

Second, the pigment used in glossy inkjet paper

In the past, calcium carbonate and barium sulphate were used as pigments, but the effect was not good. Porcelain suppliers also developed several kinds of low-gloss coated paper special porcelain, but the effect was not very satisfactory. Many pigment suppliers are now actively developing pigments for low gloss coated papers to improve product quality and reduce operational complexity. Grinded calcium carbonate (GCC) has the advantages of good fluidity and high whiteness, but it is difficult to control its narrow particle size distribution and irregular shape in the grinding process, which is not conducive to obtaining a high gloss difference. In contrast, the light calcium carbonate can control its crystal shape, narrow particle size distribution and average particle size according to its production process, and the whiteness is high, which overcomes the shortcomings of porcelain clay and ground calcium carbonate, so it is possible to consider developing a low gloss. Lightweight calcium carbonate for coated paper. Foreign countries have advanced technology in this area and have developed special spherical light calcium carbonate (SCC) for low gloss coated paper.

Calcium carbonate is one of the commonly used coating pigments in the paper industry and has a low cost, which can effectively increase the solid content of the coating and provide a good viscosity reduction effect. The light calcium carbonate (ie precipitated calcium carbonate PCC) has a small particle size, narrow particle size distribution, easy control of size and shape, high whiteness, strong hiding power, and significant application effects. However, a large amount of calcium carbonate will affect the sheet gloss and surface bonding strength, affect the print quality, therefore. Calcium carbonate is not generally used alone, and is often used in combination with other pigments. Generally, PCC is used instead of an appropriate amount of silica, and the binder polyvinyl alcohol (PVA) is used for coating configuration.

Third, the second coating

The so-called secondary coating is the pre-coating of generally inexpensive pigments on the surface of the paper to produce a relatively flat base paper for top quality pigment coating. This makes the top coat evener, resulting in better surface properties and more uniform ink absorption during printing.

With the same total coating amount, the surface of the secondary coated paper remains smooth after printing, while the primary coated paper becomes rough due to fiber wetting. Secondary coated paper also has better post-print gloss. After the coating amount of secondary coated paper was increased, the overall quality before and after printing was improved. In the same condition of the base paper, even if the total coating amount of the secondary coated paper is lower than that of the primary coated paper, the fiber coverage and the smoothness thereof are better than those of the primary coating, and the cost of the secondary coating material can also be reduced. Because the primer is made with a cheap PCC, the quality is best mentioned in the finish. In addition, the printing ink mainly stays on the surface of the secondary coated paper, thereby reducing the amount of ink used, reducing the fiber swelling and reducing the drying requirements during printing.