The corrugated shape refers to the corrugated shape of the corrugated tooth profile. The difference lies in the size of the radius of the corrugation and trough arc. There are three types of shapes: U-shaped, V-shaped, and UV-shaped. The U-shaped peaks and troughs have larger radii; the V-shaped ones are smaller; the UV-shaped ones are in the middle. Different shapes have different performance characteristics.
Looking at the advantages and disadvantages of the above three kinds of corrugated shapes, the advantages and disadvantages of U-shaped and V-shaped are obvious, and the overall performance of UV shape is to meet the general requirements of most corrugated packaging, and its superiority is undoubtedly demonstrated. Therefore, most of our country and other countries in the world use UV-shaped corrugated.
After understanding the corrugated shape overview, introduce the principle of selection of base paper for cardboard production lines from the following two aspects:
1. Grade Matching ─ Corrugated board and linerboard with similar quality grades should be used to produce cardboard. Corrugated cardboard made of high-grade cardboard boxes and low-grade corrugated paper is likely to cause collapse.
2. Quantitative Matching – Experiments have shown that improving the quantification of corrugated cardboard can help reduce costs. When the strength of the corrugated paper is kept constant, the weight of the corrugated paper is increased by 1 g/m2, so that the double-sided boardboard paper can also be reduced by 1 g/m2. Therefore, many manufacturers use high-quantity corrugated paper to produce cartons. However, corrugated board produced from high-quantity corrugated paper and low-quantity linerboard will have surface unevenness and obvious corrugation, which will affect the appearance quality and printing effect. Therefore, it is generally better to control the quantitative ratio of cardboard and corrugated paper to 2:1. If the weight of the optional corrugated paper is too low, the corrugated tooth profile will change after bonding, and the arcuate shape will change into a rectangular structure, which will affect the thickness, side pressure strength and cushioning properties of the paperboard.
The formulation of adhesives for corrugated cardboard production lines: The adhesives for cardboard production lines consist mainly of starch (or tapioca flour), gelatinizer (NaOH), crosslinker (borax) and other reinforcing agents. In fact, the starch itself does not have a binding function. Only the active hydroxyl groups in the starch molecule are oxidized to aldehyde groups, ketone groups, and carboxyl groups in a limited manner, and the official bond portion in the molecule is broken, and the polymerization is reduced to have good water solubility and affinity. And adhesion, after alkalized into a good performance starch adhesive.
Under normal circumstances, the amount of starch used for single-sided corrugated board production is: 150kg/t to 170kg/t; the three-layer dosage is: 170kg/t to 200kg/t; the five-layer and seven-layer requirements for adhesives are relatively high, and the starch dosage is 200kg /t 300kg/t. The amount of industrial caustic soda (NaOH) is determined according to the viscosity of the binder after stirring in the main carrier added to the starch liquid. Under the same conditions, the amount of caustic soda is large and the viscosity is high; when the amount of caustic soda is small, the viscosity is reduced.
Borax can make various ingredients produce molecular structure changes to form complexes, with cross-linked thickening effect. The amount of enhancer (also known as desiccant) in the adhesive, less than 2kg per ton, will not achieve its intended effect; the amount of glue per ton is higher than 8kg, and it is easy to produce cardboard brittleness. The normal dosage is 3kg/t to 6kg/t.
Determination of original corrugated board type, selection of production line base paper and preparation of adhesives
March 14 12:10:45, 2020
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