It is imperative to develop super gloss paper

It is imperative to develop super gloss paper

among them, 1 development trend of super calendered paper

1.1 current situation of super calendered paper at home and abroad

Super calendered paper (SC paper for short), also known as magazine paper in Europe, is an uncoated printing paper based on mechanical pulp, with a quantitative g/m2 and a quality between paper and traditional lightweight coated paper (LWC). SC paper is characterized by high filler content, generally 20% - 30%. The paper is super calendered and finished, with high smoothness and gloss. The main difference between SC paper and LWC paper is that the filler of SC paper is distributed in the whole slurry, while the pigment of LWC paper is mostly concentrated on the surface of the paper. Under the same ash content, LWC paper has higher gloss. SC paper and LWC paper are high value-added printing paper containing machine pulp, which can be used for gravure printing and offset printing, and are widely used in magazines, advertisements, catalogues, samples, pocket brochures, newspaper color inserts, etc. SC paper is divided into SC-A, sc-b and SCC grades. In addition, according to the slurry ratio and the different configurations of super calendering finishing equipment, there are sc-a+, sc-b+

in recent ten years, SC paper has developed rapidly in the world (mainly in Europe and North America). The average increase rate of output in 10 years is 11.5%, which is the fastest growth rate of all kinds of printing paper, including coated paper and light weight coated paper, while the growth rate of paper in the same period is only 1.5%. In the past two years, the development of SC paper has shown a strong momentum in Western Europe. It is reported that the consumption of SC paper in Western Europe increased by nearly 7% in 2000, and the price showed an upward trend. In France, due to the shortage and high price of LWC paper, SC paper has been introduced to the market. Users of LWC paper have turned to buying SC paper or even sc-b grade paper. In two years, the demand for SC paper in France has increased by more than 10%, the growth rate in Germany is more than 6%, and the growth rate in Britain is as high as 15%. The most noteworthy development is that SC offset paper is used to replace LWC offset paper. The development goal of SC paper is to achieve high quality to achieve or completely catch up with LWC paper

in recent years, great progress has been made in the development of high-speed paper gripper technology, such as dilution water slurry box, new vertical gripper, fully closed straight through press with shoe press, single row dryer, paper reeler with central drive, soft roll super calender, as well as the corresponding quality control system and the use of various chemical additives, to improve the speed of the paper machine, increase the amount of paper filler, improve the smoothness of paper, reduce the difference between two sides Good conditions have been created for the production of high-quality SC paper with consistent full width and good printability. In particular, the soft roller overpressure technology has made revolutionary progress, which is particularly important for the production of SC paper. The speed of traditional super calendering locomotive is limited to 800m/min, while the overpressure speed of the new generation of soft roller can be more than 1500m/min. at present, it has become a reality to adopt the internal overpressure on the high-speed paper machine. The production cost of SC paper is lower than LWC paper. It is reported that the whiteness, opacity, printability and other indicators of SC-A paper produced by a paper factory in North America are equivalent to LWC paper, and the production cost is 15% - 20% lower than LWC paper. High quality and low-cost SC paper has attracted paper suppliers. In Europe and North America, high-speed large SC paper machines have been launched one after another, and some uncompetitive paper machines have been transformed to produce SC paper. According to incomplete statistics, from 1998 to 2002, North America and Europe added nearly 2million tons of SC paper production capacity, with an average annual increase of 4%. Fujian Longyan super calendering paper factory, which was built in the eighth five year plan, has been completed and put into operation in the ninth five year plan. However, due to lack of funds, the factory does not have the conditions to produce SC paper. So far, there is no such product in China

1.2 quality requirements of SC paper

according to the printing requirements, SC paper is divided into gravure printing paper and offset printing paper. Gravure printing requires that the paper page has a high smoothness, dense surface, low ink absorption and good opacity. Offset printing requires not only good printability, but also high surface strength. SC-A can be used for gravure printing and offset printing, and sc-b is suitable for offset printing. In recent years, higher grade sc-a+ paper has appeared, with whiteness of 75% and gloss of more than 55%. Its quality can be comparable with LWC paper

1.3 main technical characteristics of SC paper

fiber ratio of SC paper. Traditionally, SC paper, which is produced through efficient cooperation with domestic peers, is made with 70% - 80% bleached ground stone pulp (SGW) or bleached thermomechanical pulp (TMP) and 20% - 30% softwood bleached kraft pulp (NBKP). In recent years, more and more manufacturers use bleached deinked waste pulp (DIP) to produce SC paper, with the consumption of more than 30%, and has a growing trend year by year. The #5 machine put into production by Lang Papier in Germany in 1999 uses 75% dip, 25% SGW, 5% BKP to make SC paper. Its speed is 1400-1600m/min, the ash content of the paper is 28%, the printing surface roughness (SIO) is less than 1.2pm, the gloss (45 °)> 45%, and the quality is close to the SC-A (sc-b+) standard. Schongau paper mill #9 paper machine put into operation in 2000 copies SC paper with 100% dip, and the speed is more than 1500m/min. Dip generally uses old newspapers and old magazine paper, including both mechanical pulp and chemical pulp. It can also retain high-quality fillers and fine fibers in magazine paper, which is the pulp composition required for making high-quality SC paper

the filler content of SC paper was about 25% in the 1980s, and now it is as high as 35%. The filler is generally clay or talc powder. In recent years, some paper mills have used precipitated calcium carbonate (PCC) to improve the whiteness and opacity of paper. It is reported that myllykoski paper mill in Finland uses PCC to produce a new SC paper, named m-plus, which promotes the standard SC paper to be very close to LWC paper (Table 6 is omitted). The price of standard LWC web paper is about 20% higher than that of conventional SC paper. In contrast, LWC paper has higher production cost and lower production efficiency. Now myllykoski factory can produce SC paper with higher whiteness and opacity than LWC, and the price is 10% lower than LWC. In addition, the loose thickness of paper is about 10% higher than LWC. It is certain that SC paper with low cost, high whiteness and high loose thickness will be more attractive. SC paper is a kind of paper with high-tech content, and effective chemical additives need to be added to the pulp. In this regard, China pulp and paper research institute has carried out some research work and achieved some results. SC paper has a high filler content, which can save a lot of fiber raw materials. China is rich in talc powder resources, and the price is low. In addition, using waste paper as fiber raw materials to produce high value-added SC paper, the economic benefits are obvious. At present, the vast areas of China are returning farmland to forests, planting poplar, and using poplar chemical mechanical pulp (APMP) to make SC paper is also a better choice

1.4 characteristics of equipment for producing SC paper

sc paper requires good sheet forming uniformity and small difference on both sides. Generally, in order to speed up the company's layout of lithium battery new energy materials, the difference between the distribution of fillers and fine fibers in the Z direction of the paper sheet made by the long paper machine is too large, so it is not suitable to make high-quality SC paper with high filler content. After several generations of updates, the pinch former has now developed into a new generation of vertical pinch former using the combination of vacuum forming roll and dehydration plate, including optifomer of Valmet company and tqv former of Voith company. Its common feature is that the pulp stream ejected from the headbox first passes through the forming roll for low-pressure dehydration, and then enters the wiper area for pulse dehydration. It combines the advantages of the wiper blade formers and the gaproll formers, which not only improves the retention rate, but also improves the uniformity of the paper. When producing SC paper with high filler content (above sc-b level), only mild pulse dehydration and shearing are required in the wiper area, and reverse pressure dehydration plates are generally not set to avoid damaging the surface layer formed by the slurry on the forming roll. The difference between two sides of the paper sheet made by the pinch former is very small, and the filler is distributed in the Z direction, with more on both sides and less in the middle, which is exactly what SC paper needs

the pressing form has a great impact on the two sides of the paper. SC paper, especially SC-A paper, requires not only the same smoothness on both sides, but also the same oil absorption and ink absorption. From the current trend, two straight through fully enclosed presses (one shoe press or two shoe presses) are the best choice, which not only solves the problem of the two sides of the paper, It also solves the paper introduction problem of open press caused by the decrease of wet strength of paper due to the increase of filler amount, which is particularly important when the speed of paper machine exceeds 1500m/min. The calendering and finishing of SC paper used to be dominated by external overpressure. In recent years, due to the advent of a new generation of soft roller super calender, the development trend is to adopt internal overpressure. Many of Voith's Janus MKZ and vabet's optiload have been put into actual production and operation all over the world, and the speed has exceeded 1500m/Mn. If the external overpressure is adopted, not only the investment is doubled, but also the production and operation cost is high. It is reported that the annual operating cost of in machine overpressure is only 72% of that of out machine overpressure, but if SC paper with particularly high smoothness is produced, such as the #11 paper machine newly built by laakirchen paper mill in Austria to produce sc-a+ grade paper, out of machine overpressure is still used

2 selection of process equipment for Shixian paper project

the main equipment of Shixian paper project was introduced for bidding in 2000, and finally Valmet and other companies in Finland won the bid. Previously, Shiyan Paper Co., Ltd. had organized a group to go abroad to investigate and conduct research on the domestic paper market. Electroimpact helped NASA customize a special manipulator, and had a clear understanding of the selection and configuration of the paper machine production line equipment of the project

2. L project background

in recent years, China's paper production and consumption have increased rapidly, with 790000 tons of production and 850000 tons of consumption in 1995, 1.13 million tons of production and 1.46 million tons of consumption in 1999, with an average annual growth rate of 9.4% and 14.4% respectively. The growth of consumption has greatly exceeded the growth of output, and the consumption in 2005 may exceed the predicted 2.4 million tons. With the existing domestic paper production capacity and several new large paper projects launched in the past two years, it is expected that the domestic paper production capacity will also exceed 2.4 million tons by 2005, that is, the supply and demand of the paper market will be basically balanced. According to customs statistics, 247600 tons of paper were imported in 1999 (236000 tons in 1998). With China's entry into the WTO and the acceleration of the process of global economic integration, paper will still maintain a certain amount of imports, and manufacturers will face fierce market competition. China is short of wood resources for paper production. Many paper mills, including newly launched paper projects, have turned to using waste paper secondary fiber raw materials to produce paper. Waste paper raw materials for paper production mainly rely on imports. Shixian project is no exception. The poplar chemical mechanical pulp (APMP) project originally planned to be matched with the paper project has also been changed to deinked waste pulp project

in recent years, China's waste paper import has increased rapidly, reaching 1.92 million tons in 1998, an increase of 18.3% over the previous year; In 1999, it reached 2.52 million tons, an increase of 31.4%, mainly imported from the United States. In 1999, the United States exported 7.72 million tons of various waste paper, and China's import volume accounted for about 1/3 of its export volume. With the production of projects under construction during the Tenth Five Year Plan period, the import of waste paper will increase significantly, and the price of waste paper is likely to rise. Compared with the coastal areas with developed transportation, the freight of waste paper raw materials in Shixian paper factory is higher, which is a disadvantage of the project in the cost competition. In this situation, the equipment introduction of Shixian project has to consider that while producing high-quality paper, it can also produce high value-added paper, so as to strengthen the adaptability to the market

2.2 determination of production varieties

there are two ideas in the selection of production varieties in this project: one is to change the soft roller calender in the paper machine into the soft roller super calender, and take the road of developing SC paper; the other is to increase the sizing press with metering in the paper machine to produce surface sizing paper and develop towards film coated offset paper (FCO). Both SC paper and FCO paper are promising paper types. Due to the limitation of funds, Shixian project