The growth of inkjet paper and laser printing paper will lead to an increase in the amount of pigments, especially brighteners and specialty pigments. Alkaline paper contributes to the development of this trend. Calcium carbonate pigments provide the hue needed for high whiteness and can be used with optical brighteners to meet the demanding office paper needs.
In the field of printing, digital printing has grown fastest. In office and home use, due to the dominant position of color inkjet printers, the demand for inkjet printing paper and digital printing paper has rapidly increased. Inkjet printers and desktop publishers are looking to supply higher quality paper.
At present, most paper merchants sell non-coated paper and multi-purpose paper as copy paper, laser printing paper, and ink-jet printing paper. Since these papers are produced by large plain paper machines, surface sizing is performed using internal metering rod size presses. Therefore, non-coated varieties cannot be used for high-end printing and picture printing purposes and can only be used for normal printing. At the other end of the printing field mass range is photographic quality ink jet paper and paper coated with silicon pigment and polyvinyl alcohol adhesive. These papers are coated at low speed by an off-machine coater.
The market is looking for a paper that has better performance than paper and is acceptable in terms of cost. These "intermediate" papers are close to the quality of the silicon coated paper and the production costs are reduced. The use value of these types of paper can be intermediate between expensive silicon coated paper and low quality, surface sized uncoated paper. Market research shows that the potential use of inkjet and digital printing paper to fill this vacancy is at least higher than the current market demand. Paper mills, printer manufacturers and industrial printers recognize this huge demand potential. However, in the past five years, it has been an in-depth research topic that has not been solved.
The cost of the pigment is required to be lower than that of silica gel so that it can be coated at high speed inside the machine, and cheap starch and polyvinyl alcohol can be used as the adhesive to reduce the production cost and the cost of coated paper.
At present, industrial coated ink jet printing paper is coated with amorphous silicon pigments. Generally, precipitated silicon is generally used, and fumed silica is also used. However, the high cost of silicon pigments is only part of the problem. The problem with silicon pigments in production is that the solids content must be in the range of 15% to 20%, and its fluidity is not good. Since the pores of silicon are large, the hydrophilicity is improved. Therefore, a large amount of water needs to be added during the preparation of the paint until all the pores are filled up to form a paste. Only in this way can paint be made. Generally, the coating must be applied at a concentration of less than 20%. As the coating dries, the water trapped in the pores of the silicon pigment also consumes more heat. These combined factors require that in the production of silicon coated paper, it must be carried out at a low speed external coater. Therefore, its cost is higher than that of the in-machine coater.
The recently developed modified zeolite seems to be expected to solve the problem. This pigment can be used for in-machine coating and uses metered surface sizing to make the ink jet paper print closer to silicon coated paper. This new type of zeolite pigment is far less expensive than silicon pigments.
Amelie believes that the interaction between pigments and inks has been studied in depth, and the surface performance factors of pigments have been clarified to enhance ink jet printing to minimize the spread of ink and make the printed images clear.
Digital environments for home and office use have been formed, and more sophisticated users demand highly realistic digital photos. This demand pressure forces paper mills to produce high quality paper. Engineering pigments are now, and in the future, an important part of this whole work.
Due to the quality of the ink and the type of print head, inkjet paper requires a special surface for the paper and requires a special coating in order to print a high quality image. The main requirements for the quality of inkjet papers are vivid print colors, realistic images, and fast ink absorption. Inkjet printing and coating can be summarized in three ways: no coating or surface treatment corresponding to the coated, matte corresponding to the gloss, the photo surface corresponds to the non-photographic surface, or the pigmented corresponds to the resin coating. Cloth.
Current high-quality inkjet paper coatings use high surface area aluminum as the pigment. Most common porcelain or calcium carbonate-based pigments do not have enough surface area or pores to rapidly absorb ink (water-based). Therefore, they are not suitable for ink-jet paints. However, a few clay and calcium carbonate-based pigments have been substantially modified and are gradually entering the inkjet coating market. Most ink-jet printing papers have been developed to high-quality grades. Obviously, there are still gaps in the mid-quality level.
For office and home inkjet paper, the main role does not lie in porcelain clay and calcium carbonate pigments. However, if the paper processing factory produces some medium-quality varieties between copy paper and high-quality photographic paper, this situation will be quickly reversed.
The use of pigments in these applications requires a high surface area and pore-controllable structure to facilitate ink absorption and imaging.
Source: Shanghai Packaging