Discussion on corrugated board production technology experience (1)

I. Overview

Dialectical materialism believes that labor creates human beings. In today's society, the survival of mankind is inseparable from the production activities, and all production activities are inseparable from the product packaging. This is true both in ancient and modern times. The definition of the so-called packaging is: "To protect the product in the circulation process, facilitate storage, promote sales, according to a certain technical method used in the container, materials and auxiliary materials." In the entire packaging materials, paper products accounted for packaging The largest proportion is 45.25%, followed by other glass, plastic, wood products and metal materials. In paper product packaging, corrugated cardboard (box) packaging accounts for the vast majority.

Corrugated cardboard packaging containers are functionally superior to the 10 features of other types of packaging:

The plasticity of the modeling structure can be arbitrarily cut, punched, folded, etc.; the convenience of the packaging is easy to use - it is light in use, flexible in structure, and flexible in texture; it can be both rigid and flexible - it can be used as a packaging and external force. Ideal protective mediators; beautifying the promotional nature of goods - able to produce a variety of variegated structures and beautiful decoration printing; the suitability of the flow effect - can use different quantitative, different grades of raw paper to produce different sizes of containers Low cost of packaging—primary material is base paper; use of resource availability—Compared with traditional wood products, the wood consumption of corrugated paperboard base paper only accounts for 30% of wood product packaging; easy to recycle—the basic raw material is The base paper can be easily recycled after use, and the recycling and recycling rate can reach 75%. The superior green environment--after use, the corrugated board can be burned, non-toxic, degraded quickly and will not cause pollution to the environment; - Due to the foldable lightweight hardware package, it is possible to make efficient use of the positions and transport loading space.

Looking at the current situation of China's carton industry, it can be summarized in 12 words: rapid development, overcapacity, and bright future. The carton industry has undergone the first major transformation in the past 25 years. From this year on, it will enter the second major change. The characteristics of this change are adjustments.

China's carton industry has entered the stage of primary industrialization since 1995, when there were 600 production lines; in 2000, it was 1,600; by 2005, it had reached 4,000.

In 1995, the output of corrugated board in the world was 110.4 billion m2, in 2000 it was 125.3 billion m2, in 2003 it was 139.5 billion m2, and the annual growth rate was 3.3%. The top three world production rankings in 2000 were: North America (34%), Asia (31%), and Europe (27%). The output of corrugated paperboard in China was 7.4 billion m2 in 1995, rising to 12.3 billion m2 in 2000, and reaching 15.8 billion m2 in 2003, which is 34% of Asia's total output and 11.3% of the world's total. From 1995 to 2000, the average growth rate of paperboard production in China was 12%, and the average growth rate in the world was 2%. From 2000 to 2003, the annual growth rate of paperboard production in China was 9%, and the world's annual growth rate was 3%. The output of China in 1996 was 8 billion m2, which was only half of that in Japan. In 2003, it was 15.8 billion m2, which surpassed Japan.

More than 50% of the cartons in China accounted for more than 80% of the total, the United States, the third floor of the box accounted for 89.4%, Japan, the third floor of 84.6%, with two layers of paper is equivalent to a waste of 2/5 paper. This is because western countries have realized that they must save limited timber resources. The use of high-strength, low-weight base paper has become an inevitable trend.

Shanghai Tobacco Group has completed a joint reorganization across regions and will become the vanguard of several leading companies under China National Tobacco Corporation. As its main professional supporting factory, Shanghai Baiyulan Tobacco Material Co., Ltd. has undertaken over 85% of the Group's carton packaging production tasks.

Second, the determination of the original rake type, the selection of the production line base paper and the deployment of adhesives

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 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 comprehensive performance of UV shape is to meet the general requirements of most corrugated packaging, and its superiority is undoubtedly demonstrated. Therefore, most of the countries in China and other countries use UV-type 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. The use of corrugated board made of high-grade linerboard and low-grade corrugated cardboard is liable to cause collapse.

2. Quantitative Matching – Experiments have shown that increasing the amount of corrugated paper helps 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 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.