Lightly coated paper - the most popular printing paper
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From last year to the new millennium - early 2000, the mainland paper industry and many propaganda media are very concerned about a new concept and new paper, its name is light coated paper.
What is light coated paper? It is the abbreviation of lightweight coated paper. It is also called low-quantity coated paper. Its English name is LWC paper (Light Weight Coated Paper) is internationally used. It is called pictorial paper or light coated paper in Taiwan.
meaning
Light coated paper refers to a class of less-quantized coated papers. It is made by adding a thin coating (made of calcium carbonate, cationic starch, etc.) on the front and back sides of the base paper, and then supercalendering to improve its physical properties and printability. The light-coated paper fiber material is generally 40% of softwood bleaching chemical pulp; mechanical wood pulp (or TMP, CTMP) accounts for 60%. This can greatly reduce production costs. The basis weight of the base paper is relatively low, about 40~50g/2. The coating amount is usually 6 to 10 g/2 (single side). Therefore, the weight of the light-coated paper is 52~70g/2, which is the sum of the base paper and the amount of the two sides.
Characteristics
What are the characteristics of light coated paper?
One is the high quality. From the paper's performance, the light-coated paper is between the coated paper and the offset paper, and its color printing effect is comparable to that of coated paper. It also has good opacity and slipperiness, as well as printability and high gloss (including paper gloss and print gloss). This provides a solid foundation for printing quality publications.
The second is low cost. Because of the relatively inexpensive mechanical wood pulp (as opposed to bleached chemical wood pulp) in light-coated paper production, the investment in raw material costs is reduced by about 30%. This will increase sales and improve efficiency.
The third is a high added value. Lightly coated paper is processed paper, which is more expensive than general offset printing paper. However, it is much cheaper than coated paper that is coated with all chemical wood pulp. Obviously, increasing the profit of sales becomes the inevitable result of logic.
By the way, because the weight of light-coated paper is generally lower than that of coated paper, it can reduce the postage of airmail, so it is popular with magazines, newspapers and magazines that are distributed globally or widely. However, due to the low durability of light-coated paper (subject to the influence of a large amount of mechanical wood pulp in the base paper, compounds such as lignin remaining in the mechanical wood pulp cause the paper to become discolored, brittle and damaged). It is more suitable for printing prints that do not need to be preserved for a long time.
use
LWC paper is widely used in printing magazines, catalogs, advertisements, trademarks, newspaper specials (inserts) and so on. In the United States, 52% of LWC paper is used to print magazines, such as Reader’s Digest, which publishes tens of millions of copies in 19 languages each time (for example, there are more than 260 pages in each period). The text of this magazine is printed on LWC paper. In addition, 25% of LWC paper is used in catalogues; 20% of print ads. In Europe, 42% of LWC paper is used for printing magazines, 30% for advertising, and 22% for catalogues. In more developed countries and regions, the reason for the increasing demand for LWC paper is mainly due to the tremendous impetus for the development of advertising and color printing. It is reported that 95% of the world's mail-order businesses are concentrated in the United States, Europe and Japan, and the largest mail-order markets are the United States, Germany, Japan, France and the United Kingdom, which account for 90% of the total mail-order sales.
In the big picture, although the commercial advertising industry is challenged and competitive by the increasingly popular electronic media, such as TV shopping, telephone ordering, online mailing, faxing and so on. However, the commercial advertising and catalogue markets are still quite active. In order to save time and convenience, people like to take a piece of paper printed matter (of course, color printed), and arbitrarily read it regardless of time and place. In the past, coated papers, which were popular in the advertising industry, were gradually replaced by LWC paper because of their large size, heavy weight and high cost. Moreover, general TV commercials can only be short-term stimulating, and they are forgotten. Print advertisements have long-term effects and can be repeatedly circulated and reminiscent of aftertaste. Comparing the two, it is understandable that the demand for LWC paper is increasing.
produce
The production of LWC paper is more complicated than ordinary printing paper. In addition to using different pulps for separate beating, the selected paper machine is preferably a mesh former, and the headbox is closed to ensure a speed of 1200-1500 m/min. The base paper which is produced on such a paper machine can be coated in a paper machine and then sent to the outside of the machine for processing by a super calender. The in-line coating device is installed between the press section and the drying section, and a light applicator is installed. The paper web is lightly coated and then heated by a drying oven to facilitate drying of the coating coating and prevention of paper sticking. phenomenon. The two coating process is advantageous for improving the quality of the paper.
The light applicator is a combination of a feeding roll, a back roll and a doctor metering. The coating is metered through the doctor blade and sent to the backing roll, whereupon the coating applied to the backing roll is transferred to the web. The web passes between the two rolls to overcome or avoid paint splashing and to help increase the speed. The coating amount of the coating is required to be uniform, otherwise it is easy to produce an "orange peel" paper disease.
The coating of LWC paper is made of calcium carbonate (precipitated calcium carbonate, ie PCC, particle size less than 2um), porcelain clay, and is prepared with carboxymethyl cellulose (ie CMC), cationic starch, latex, etc. It has excellent rheology and water retention, as well as the properties of a lubricating blade to ensure reliable coating quality after processing. Depending on the variety, each time the paint is changed, the preparation device and piping must be reinforced to prevent adverse effects or side effects from deposits on the finished LWC paper.
development of
The history of plain coated paper is very early, and light coated paper was born around the late 1960s. In the mid-1980s, Finland developed a Machine Finished Coated Paper (MFC). The coating operation and the calendering treatment of the paper are all performed in a (papermaking) machine, thereby reducing the investment cost and reducing the labor intensity. The MFC paper has a basis weight of 52 to 70 g/2, which is not as smooth as LWC paper, but its whiteness and bulk are higher than the latter.
In 1992, the global paper market was in a depression. In order to increase the proportion of mechanical wood pulp in the printing paper without reducing its quality. A new breed in Germany has been successfully researched - called Film Coated Offset Paper, or FCO paper. The main feature of this paper is that it produces a coated paper with a basis weight of 51~60g/2 through a film coating process, and has high opacity and bulk. At the same time, its coating method is especially suitable for low strength. Raw paper with more mechanical wood pulp (or waste paper pulp or even straw pulp). Some people think that FCO paper is the development direction of light coated paper in the future.
As the reader's whiteness requirements for paper are getting higher and higher (in fact, this is not entirely correct), the production of base paper for light-coated paper will be more neutral papermaking technology. Neutralized light-coated paper is very common in Europe; in Japan, most coated papers containing mechanical wood pulp are also "neutralized". However, dry acid papermaking is still in place in North America. The development of the coating process, as the protagonist of the coating pigment - the amount of calcium carbonate will certainly increase, especially the amount of precipitated calcium carbonate (PCC) and ground calcium carbonate (GCC) may increase to 20% ~ 50 of the total amount %. Furthermore, the increase in postage in various countries will reduce the quantification of light-coated paper, even as low as 35g/2, and the total coating amount (two sides) will reach 8g/2. It is understood that the use of light-coated paper with a basis weight of less than 51g/2 in North America accounted for 18% of total printing paper in 1992 and an estimated 35% in 2002. The user's gloss requirements for light coated paper are not too harsh, but the printing gloss is highly valued. From the development trend of the printing industry, the proportion of gravure printing will be reduced, and the demand for high-speed web offset printing paper will increase rapidly; the combination of lithography and paper (especially light-coated paper) may cause More people (and of course the participation of ink workers) are of interest.
status quo
Nowadays, light-coated paper has become a hot topic in printing paper at home and abroad. For the time being, let's not talk about some foreign plans recently. In general, the development of this kind of paper is quite fast, and its production level and product quality have been significantly improved. Taking the statistics from 1993 to 1995 as an example, the growth rate of LWC paper is 8.5%, which is higher than other countries in the same period. The growth rate of paper grades (about 4%) is more than doubled. The production of FCO paper has caught up with LWC paper. It is really the wave of the Yangtze River.
According to the "Ninth Five-Year Plan" proposed by the State Press and Publication Administration, by the year 2000, the printing industry in China will implement computer laser photo-distribution technology, and lead-lead printing (plain printing) will no longer exist. From 2000 onwards, after five years, letterpress paper was basically replaced by offset printed paper and other paper types (such as light coated paper). It is predicted that the market demand will be 400,000 to 450,000 tons at that time, accounting for only 10% to 12% of the annual printing paper volume.
The light-coated paper industry in China started late. Since the 1980s, several in-machine coating devices have been introduced from Europe, and after domestic self-made, there are more than ten production lines and total production capacity. For an annual output of 50,000 tons, it is far from meeting market requirements. At present, the light-coated paper produced by the paper mills in the Mainland, such as 65g/2LWC paper produced by a certain paper mill, is made from self-made syrup, poplar wood pulp and bleached white coniferous kraft pulp. There is still a certain distance compared to the LWC paper standard on the market. Therefore, the imported light-coated paper market is quite "hot".
It can be expected that as long as the financial and technical guarantees are made, the development of light-coated paper in the future is incalculable.