Application of nanotechnology in paper industry

2022-08-02
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Paper specification international standard application of nanotechnology in the paper industry

paper specification means that after the paper is made, it is trimmed and cut to a certain size. In the past, the size of paper was expressed by the number of "Kai" (such as 8 Kai or 16 Kai). However, the supply structure based on primary processing products has not been fundamentally improved. Now China adopts international standards, which stipulate that A0, A1, A2, B1, B2 And other marks to indicate the size of the paper. The standard specifies that the proportional relationship between the width (expressed in x) and length (expressed in Y) of the paper is x:y=1:n

according to the basic area of paper format, the format specification is divided into a series, B series and C series. The format size of A0 is 841mm × 1189mm, with a width area of 1m2; Size of B0 is 1000mm × 1414mm, with a format area of 1.5m2; The size of C0 is 917mm × 1279mm, with a width area of 1.25m2; The format specification of copy paper only adopts series a and B. If A0 paper is split in half along the length, it becomes A1 specification. If A1 paper is split along the length direction, it becomes A2 specification. In this way, it is split to A8 specification; B0 paper is also split to B8 specification according to this method. The dimensions of A0 ~ A8 and B0 ~ B8 are listed in the following table. Among them, A3, A4, A5, A6, B4, B5, b6

7 format specifications are commonly used for copy paper

I. The role of nano powder in paper manufacturing

in the printing field, like ink and coating, the application of nano powder materials in paper has also shown good results. We know that paper is the most commonly used material in printing and packaging, and its quality is the best embodiment of the quality of printed matter. Due to the coarser fibers of trees, bamboo, hemp and other fibers used in traditional paper, the larger particles of coatings (such as calcium carbonate) and fillers (such as kaolin) and the poor performance of some ingredients such as glue, there are some defects in traditional paper. For example, ordinary paper has the disadvantages of being afraid of water and moisture. Offset printing paper and electrostatic copying paper have the functions of waterproof and moisture-proof, but writing is not convenient, There are also some special properties that cannot be realized, which affect the quality of printed matter. In recent years, with the rapid development of nano materials science, nanotechnology has been more and more widely used in the paper industry, and new achievements are emerging. Related to pulping and papermaking are nano chemistry and nano materials, which may cause a new leap in the development of the paper industry and improve the quality of printed matter again

according to the current technical level and the practical application of paper, wood fiber can only be processed to the level of micron (nm). Because the cell diameter of wood is relatively large, the cell structure of wood can be changed and the growth of cells can be controlled through wood nanotechnology, which may change the characteristics of wood. For the vast majority of wood, when the fiber is processed to the micron level, the cell tubes of wood cells have all been broken, and the viscous liquid in the cell tubes can flow out easily. After mechanical pulping, there is no need to use chemical methods to extract harmful liquids and separate fibers from the cell tubes. If the wood is processed to the nanometer level, the original cell structure of the wood will be destroyed, and the fiber structure will change. Cellulose, hemicellulose and lignin can be separated by mechanical methods in the processing process, which can greatly improve the pulping rate and reduce the environmental pollution caused by the pulp and paper industry

in addition, with the rapid development of science and technology, people will have higher requirements for paper performance and quality. In addition to conventional printing and writing paper, the demand for paper with special functions is also increasing. As a special auxiliary agent for special paper manufacturing, nano materials are attracting more and more attention. At present, in the papermaking industry, nano materials are mainly used for the development of functional paper such as water-resistant, antibacterial, antistatic, anti-aging, flavoring, flame retardant, discoloration, etc., and some products have been put on the market. The application of nanocomposites in the field of packaging and printing will completely change the face of the field of packaging and printing and open up a new road for packaging and printing

although nano materials and nanocomposites have good properties and wide applications in the field of papermaking, the research and development of nano materials is not yet mature and perfect, and there are still some problems to be further studied and solved, such as crushing, agglomeration, dispersion technology, etc., which are not ideal and need to be further improved. For the performance testing of nano products, the product standards need to be further improved. However, it can be predicted that with the reduction of the production cost of nanoparticles and the increase of functional nanoparticles, nanotechnology will play a greater role in the printing field and paper industry, bringing infinite vitality and vigor to the printing and related industries

II. Nano paper that has been produced and applied at present

1 Nano lithopaper

as we all know, straw pulp, wood pulp, bamboo pulp, hemp fiber, etc. are the most basic and common raw materials for papermaking. However, with the application of nano high-tech in the papermaking field, a new technology has been developed to use stone for papermaking. This paper made of stone is called nano lithopaper. It was first successfully developed by Mr. liangshihui, a Taiwan Longmeng technology enterprise, in early 2001 and began production at the end of the year, Now this kind of nano paper has been produced by many companies

lithopaper is made by coating nano calcium carbonate on the substrate. In view of the characteristics of nanometer, any substance can be coated when it reaches the nanometer level. As the stone is rich in carbonic acid, it has become the preferred material in practical application. The papermaking process of Shike paper is strictly different from the traditional papermaking process. It is required to be closer to the plastic manufacturing process, and the production equipment is also more similar to the plastic manufacturing equipment, and its process flow is not as complex as the traditional papermaking. An important difference between the two is that the production of Shike paper is not to use pulp to make paper, so there is no need for a drop of water in the whole process. Compared with the huge water consumption of traditional paper, this can be regarded as a revolutionary progress. In addition, the papermaking process of Shike paper has stricter requirements on the environment than the traditional process. It requires very fine and clean. As long as there is a little impurity, it will affect the surface smoothness and smoothness of the paper. Although only one kind of color ink-jet printing paper has been vigorously produced and launched, the paper samples of printing paper such as paper and coated paper have also been produced. Therefore, it can be believed that with the deepening of research, the large-scale production of other printing paper will not be far away

compared with traditional similar products, this new color ink-jet printing paper (Shike paper) has the following advantages: (1) because it is objectively made of wood fiber, but is coated on the substrate by nano stone powder, its measurement requirements cannot be guaranteed. Its particle shape makes the paper surface composed of numerous holes. Therefore, the ink absorption is firm, the ink-jet printing is not easy to be soaked, and it is also waterproof. (2) The traditional wood pulp paper has fiber, which is easy to be inked, while the stone paper has no fiber, which does not exist inking phenomenon, so the definition of inkjet printing is high. Inkjet printing paper requires very high resolution. All litho papers have reached 2880dpi accuracy. Polyglutamic acid as a fertilizer synergist has important utilization value, and the effect is particularly good. If the surface of lithopaper is not covered with film, the inorganic matter on the surface will not react with ink, thus avoiding the occurrence of color deviation and decolorization. (3) Compared with traditional color ink-jet printing paper, lithopaper is more ink-saving. The 720dpi precision of Shike paper is the same as that of the traditional 1440dpi precision. Under the same definition requirements, Shike paper can save half of the ink. (4) The raw materials used for Shike paper are inorganic substances, which do not react with ink, nor with acid-base components in the air. They do not change color and turn yellow. They are more suitable for the preservation of valuable files. The traditional photo paper has the requirement of shelf life, and can not be used after two months of unsealing. However, Shike paper can easily solve this problem, and there will be no problem of being out of date for how long. (5) Easy to recycle. Shike paper will be weathered into stone powder after three months' exposure, which is conducive to environmental protection. (6) Low cost. Shike paper uses cheap stone as raw material, so its cost is low. Compared with the traditional color ink-jet printing paper, its cost is only 25% and its price is only about 1/3, which fully improves the competitiveness of its products. However, the current product specifications of Shike paper are not complete, and are mainly limited to A1, A2, A3, A4, these conventional small format ranges. Large format products are still blank. However, with the development of science and technology, it should be no difficult to produce large format products

2. Antibacterial nano paper

many organic antibacterial agents have shortcomings such as poor heat resistance, volatile, easy to decompose and produce harmful substances, poor safety performance and so on. Therefore, people actively develop and study inorganic antibacterial agents, and the use of ultra-fine technology can produce submicron and nano-sized inorganic antibacterial agents, which can well solve the shortcomings of organic antibacterial agents. Nano scale inorganic antibacterial agents include pigments, oxides and a variety of compounds. By mixing nano inorganic antibacterial agent into paper size and surface sizing solution, the paper antibacterial industrialization can be realized, such as physical antibacterial composite fiber non-woven fabric, medical food packaging paper, high-grade household paper, etc. Inorganic antibacterial agents mainly include silver, copper, zinc, sulfur, arsenic and their ionic elements. Photocatalytic antibacterial agents include nano-sized titanium oxide, zinc oxide, silicon oxide, etc. they can kill and eliminate bacteria and debris together, thus surpassing the performance that traditional antibacterial agents can only kill bacteria themselves. At the same time, it can also decompose the toxins secreted by bacteria, while traditional antibacterial agents cannot eliminate bacterial debris and toxins. Mod series nano high-performance inorganic antimicrobial determines the different bacterial agents used in the sensor, and solves the worldwide problem of discoloration in the application of inorganic antimicrobial agents, with 0.% The anti-bacterial rate of packaging products with added amount can reach 99.9%. At present, it is used in anti-bacterial packaging of milk and beverages, plastic products, functional coatings and special paper

3. Wear resistant and anti-static nano paper

in the diversified packaging of industrial supplies, especially the packaging lining paper of high-precision instruments and electrical appliances, stainless steel materials with high finish requirements and various alloy materials, the packaging paper is not only required to have waterproof, oil-proof and rust proof properties, but also required to have the characteristics of high strength, wear-resistant, anti-static and anti-aging. However, it is difficult for ordinary paper to have these characteristics at the same time. But if you set 0 This special paper, which is made by infiltrating about 3% of nano titanium dioxide, chromium trioxide, zinc oxide, iron trioxide, tin oxide and other powders into the papermaking slurry, can have excellent wear resistance, water resistance, corrosion resistance and other effects. At the same time, it can also produce good electrostatic shielding performance, greatly reduce its electrostatic effect, and greatly improve the safety factor of packaging products

4. Dyeing nano paper the pigments used for paper coloring can be divided into two categories: dyes and pigments. Most of the pigments used for dyeing are natural inorganic pigments, and some are organically synthesized. The pigment is insoluble in water and has no affinity with fiber. Its dyeing performance is not as good as that of dyes. However, the pigment has strong optical rotation resistance and strong resistance to acid, alkali and other chemical agents. Although dyes are easy to color, they are easy to hydrolyze, with large loss in the wet end, strong pollution, poor color fastness of the paper, and are not resistant to acid, alkali and other chemicals. If nano pigments are used, the problem of color fastness of colored paper can be solved. Recent studies have found that nano-sized oxide

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