Raw materials for corrugated board
Paper and paper paddles can be made from a variety of plant fibers, but the most used materials as paper are trees and non-wood.
Second, the chemical composition of wood
The following table shows the typical chemical composition of softwood and hardwood. However, it is difficult to accurately formulate the chemical formula of wood because wood is a complex and heterogeneous natural product composed of a variety of molecular compounds. The main components of wood are cellulose (40-50%), hemicellulose (20-35%), wood (20-30%) and solvents (3-3, 5%). However, it is impossible to say that these chemical components should be sorted out without structural changes and decomposition. If the main composition of wood is studied, most of it is composed of polysaccharides, accounting for about 60-80%; if wood polysaccharides are hydrolyzed with dilute acid, it can be known from glucose, mannose , Xylose and other monosaccharides composed of high-molecular carbohydrates.
The main polysaccharide component of wood can be divided into cellulose full cellulose hemicellulose
Treating whole cellulose at room temperature with a dilute base (for example, with 17, 5% NaOH or 10-24% KOH), 15-30% of the dissolved wood is hemicellulose, and cellulose is insoluble. .
The raw material of the paper is pulp, which is mainly made of wood. The manufacturing method is generally as follows: Chemical Pulp Pulp Pulp Chemical Pulp Pulp (Physical) Pulp
1, chemical pulp
Chemical pulp is a pulp made mainly of chemicals in the process of manufacturing pulp. Certainly, there are certain differences depending on the drugs used and the manufacturing methods. Compared with the process pulp which removes the intermediate lignin and cell lignin in the raw material, there are disadvantages of low raw material utilization and high production cost.
(1) Kraft pulp
Kraft pulp is a chemically produced pulp called kraft pulp. The word Kraft means solid in Sweden. Because the paper produced by the Swedish chemical factory made from the pulp produced from by-product Glauber's salt is very strong, it is called kraft paper.
(2) Semi-chemical pulp
Semi-chemical pulp is a kind of pulp made by chemical treatment and first removing some of the lignin contained in the wood, and then breaking up the remaining softened wood chips by mechanical means. That is to say, chemical processing and mechanical processing each account for half of the manufacturing methods. Semi-chemical pulps have higher purity and strength than crushed wood pulps, ie mechanically processed pulps, and have higher yields than chemically made chemical pulps.
2, waste paper pulp
Waste paper pulp is waste paper that has already been used. It is placed in a dredging device such as a masher and twisted back and forth to decompose fibers that coalesce together to form a congee.
The waste pulp used for the surface sizing of corrugated board is mainly made of kraft paper and Corrugated Paper, and therefore has a high strength.
Second, the distinction between paper and cardboard
According to its thickness, it is divided into paper and cardboard. It is customary to refer to a thick paper having a weight exceeding 200 g in a square area as cardboard, and a paper weighing less than 200 g as paper. However, with the improvement of mechanical equipment, materials, and process technology, thin paperboard has emerged as light-weight corrugated paperboard and paperboard. Its scope has exceeded the secular regulations of 200g. It is also divided into heavy-duty corrugated paperboard production lines and lightweight corrugated medium in production machinery. Paperboard production line, our company's existing three cardboard production lines are all light board production lines.
Third, the identification of the positive and negative of paper or paperboard
No matter what kind of paper or paperboard has both positive and negative aspects, when making paper, the wet paper web and the net contact surface are opposite and the other side is positive. On the other hand, due to the contact with the copper mesh, the loss of fine fibers and fillers was more, showing screen printing, so the reverse was rough. The front is more compact, and the nature of the front and back is obviously different. Its smoothness is higher on the front side than on the reverse side, and the reverse side of the pulling speed is larger than the front side; the back side of the white point is better than the front side, so the paper and the cardboard have two sides.
Two-sidedness has a great influence on print quality. In general, the smoothness of the front surface and the degree of sizing are good, so the printing performance is also good. The face paper of the carton must be made with the front side of the paper facing outwards in order to print and carry out moisture-proof treatment. For this purpose, the front and back of the paper or paperboard must be identified.