Today we talk about different raw materials pulp making for paper. Generally, we use wood pulp for paper making. It is basic raw material for paper making.Some plants are the good raw materials for papermaking. Plants commonly used for pulp making materials are classified into four categories: stem fiber, bast fiber, seed-hair fiber and wood fiber. Among them, wood fiber is the most important category. At present all over the world, wood resources cannot meet growing needs of pulp and paper making industry. In order to make up for the lack of raw materials, a considerable amount of pulp is imported from abroad.
Pulp making for paper refers to the use of chemical method, mechanical method or a combination of these two methods. As raw materials, plant fibers are made into bleached or unbleached pulp by the dissociation production process.
Mechanical Wood Pulp for Paper
Mechanical wood pulp, also known as ground wood pulp (GP), is made by using mechanical method to grind the fiber material. It occupies an important position in the papermaking industry. It has the characteristics of low production cost, simple production process, strong ink absorption, soft and smooth of finished paper, high opacity. It is suitable for printing. However, due to short fiber and high non-cellulose component content, paper strength is low. In addition, since most of the lignin and other non-cellulosic materials in wood are not removed, the paper produced by it is easily yellowish and brittle and cannot be stored for a long time. Mechanical wood pulp for paper usually refers to white mechanical wood pulp and brown mechanical wood pulp. White mechanical pulp is mainly used for newsprint paper, but also used for copy paper and printing paper together with the use of other paper pulp. Brown mechanical wood pulp for paper is mainly used for package paper and cardboard, especially industrial cardboard.
Sulphate Wood Pulp for Paper
Sulphate wood pulp for paper is to take the mixture of sodium hydroxide and sodium sulfide as a cooking agent. In the cooking process, the effect of medicine liquor is more moderate and the fiber is not strongly eroded, so it is strong and powerful. Thus, the paper made of it has the features of good folding endurance and brusting strength and excellent tear strength. It generally can be divided into bleached pulp and unbleached pulp. The unbleached pulp is available for the manufacture of kraft paper, sack paper, kraft cardboard, and common package paper and cardboard. The bleached pulp is used to make advanced printing paper, drawing newspaper, offset paper, writing paper, etc.
Sulfite Wood Pulp for Paper
Sulfite wood pulp for paper is to take the mixture of sulfurous acid and acid sulfite as a cooking agent. The pulp has the features of long, soft and tough fiber, strong strength, easy bleaching and excellent interlacing ability. According to their refinement, it can be divided into unbleached pulp, semi-bleached pulp and bleached pulp. The unbleached pulp is yellowish and its fiber is also harder, so it is mainly used for medium printing paper, thin package paper and translucent paper and oil-proof paper for containing a small amount of lignin and colored impurities. The semi-bleached pulp contains a lot of pentose, so it is used for producing transparent tracing paper and imitation parchment. The fiber of the bleached pulp is white, pure and soft in texture, but due to the bleaching treatment, the fiber strength is lower than that of the unbleached pulp. So the pulp is used for making all kinds of advanced paper.
Waste Paper Pulp Making for Paper
Waste paper pulp is made of waste paper or paper trimmings by the cutter of the printing plant as raw material through mechanical stirring, bleaching and deinking treatments. The strength and performance of the fiber in waste paper pulp is determined by the type of waste paper pulp. However, the fiber is eroded again by chemical solution or damaged by mechanical force, it is worse than that of the original. According to the quality of waste paper pulp, it is respectively used for the manufacture of printing paper, writing paper, cardboard and lower level paper.
There is a wide range of raw materials of pulp making for paper. In addition to the above described several kinds of pulps, there are straw pulp, reed pulp, bagasse pulp, bamboo pulp, cotton pulp, linen pulp and synthetic pulp.
Pulp Composition
Main component of the fiber is cellulose. In addition, it still includes hemi-cellulose, lignin, resin, pigment, pectin, ash and other substances. Among them, the cellulose and the hemi-cellulose are essential components, and the other components belong to the matters that shall be removed.
Main Performances of Paper Pulp
There are many pulp performance indicators. They can be broadly divided into two categories of physical and chemical performances. The physical performance is an important indicator of judging the pulp value. The tensile strength, bursting strength and tear strength are main assessment index of imported pulp. At present, a larger amount of the bleached and unbleached sulphate pulps, the bleached sulfite pulp and mechanical wood pulp is imported.
Inspection Standards of Pulp Making for Paper
The inspection standards of the imported pulps mainly include weight inspection and physical performance inspection. The inspection standards are TAPPI, ISO, SCAN, APPITA, CPPA, etc.
Fibrous Raw Materials
Fibrous raw materials of pulp making for paper are fibrous materials obtained by chemical or mechanical processes with the characteristics of intertwining or binding to paper. Common pulps are mostly made of plant materials. At present, more than 90% of the world's total pulp output is wood pulp, and the rest is mainly made from raw materials such as straw, wheat straw, bamboo, reed, bagasse, cotton and hemp. The fibrous materials have the characteristics of intertwining or binding into paper. Their main ingredient is cellulose. Animal fibers such as wool, mineral fibers such as asbestos, rayon, have been made as the papermaking raw materials, which is also known as pulp. Pulp often contains some water. As its water content is less than 20%, it is called dry pulp; as its water content is about 50%, it is called wet pulp; as the water content is above 90% or more, it is called liquor pulp.
Different raw materials pulp making for paper industry need to use different paper pulping equipments. Anyang Machinery Co., Ltd. affiliated to China National United Equipment Group Corp. is a professional straw, wheat straw, bamboo, reed, bagasse, cotton and hemp manufacturer. If you need paper pulping equipment, please feel free to consult us.
