Research and Countermeasures on Corrugated Board Phenomenon and Bonding Problems (1)

Corrugated board quality is caused by a variety of factors, such as: paperboard board-like phenomenon, cardboard warping uneven, poor bonding, leakage pit, pit paper is not in place, compressive strength, anti-jamming strength can not meet the requirements. Some problems are more intuitive, while others are hidden and complex. Influencing factors often coexist, and mutual restraint is intertwined. Therefore, there is a need for theoretical research on quality issues. This article focuses on the concrete analysis of the corrugated board phenomenon and poor adhesion.

(1) Research and countermeasures of corrugated board phenomenon in corrugated board
Corrugated cardboard is composed of core paper, core paper, face paper, and bottom paper. Needless to say, the quality of the base paper plays a decisive role in the quality of corrugated board molding. Carton manufacturers should not only purchase qualified raw paper, but also pay attention to observe different production situations in production, and control and adjust them at any time. Otherwise, there will be cardboard quality problems due to improper production control.

l. Influence of moisture content of raw paper

When the board has a see-saw phenomenon, it is generally first considered whether the operator has adjusted the key parameters of the key point as required. Such as: cardboard tension control; single steam spray on the machine to adjust the level of wet and dry corrugated paper and control: the control of production speed and whether the vapor pressure meets the requirements and other issues. And often overlooked a very important factor - the moisture content of the base paper. It is often believed that a slightly higher or lower moisture content is not a serious problem. As long as the base paper can be produced on the machine, no cardboard debonding will occur. Actually, the problem of the paper's retractability depends largely on the moisture content of the paper itself. For qualifying base paper, corrugated paper must be strictly controlled at 8±2% and linerboard controlled at 9±2%. Excessive water content will cause the paper fibers to expand and elongate due to excessive moisture ingestion; and too low moisture content will not be conducive to paper bonding and molding, which is particularly evident on the use of low basis weight raw paper. As low-volume corrugated paperboard has the advantages of low quality and low price, today it is facing the rising international pulp market, it is being widely advocated and promoted by the carton manufacturers. However, due to the low basis weight of paper and the thinness of paper, it is difficult to manufacture corrugated paperboard. It is often due to improper adjustment of the production that the surface of the paperboard is squid-like or blisters, resulting in quality problems such as unevenness of the paperboard and the impact of printing.

2, the impact of the amount of sizing

Corrugated cardboard is a physical deformation of the backing paper at the top of the paperboard. It changes the tight, flat surface of the paperboard and forms irregularities along the sides of the corrugations. In addition, blistering has also been accompanied, and it has mainly occurred in low basis weight papers. One of the main reasons is the excessive amount of adhesive sizing.

As far as corrugated board production is concerned, there are many sizing problems in either single-sided or double-sided machines. For single-sided machines, the speed of the sizing roller is slightly slower than that of the corrugating roller in the design of the gluing machine to ensure that the sizing roller conveys an appropriate amount of adhesive and is evenly applied to the corrugation crest. When the paper is bonded and pressed, the adhesive penetrates into the paper fibers and then solidifies to achieve a bonding effect. However, when the amount of glue applied by the adhesive is excessive, the excess adhesive is pushed out to both sides of the corrugation peak, causing the sizing line to become wider and larger. When these excess binders are dried, they shrink, and this shrinkage force will pull the paper back. When a single-sided machine uses a high basis weight paper, it has sufficient tightness to withstand this tensile force so as not to cause the bottom paper to shrink and distort. When a low basis weight paper is used, the low tension cannot be used. Resistance to wave tension and easy to cause the end of paper shrinkage deformation (see Figure 1).

Similarly, for the double-sided machine, when the low-precision paper is used, it will also cause shrinkage and deformation of the tissue due to the inability to resist the pulling force of the wave, resulting in unevenness, and in severe cases even blistering. Therefore, the only solution when using low basis weight raw paper is to strengthen the control and adjustment of the production process and try to overcome the quality problems caused by the low basis weight of the base paper. In the case of ensuring the adhesion of the cardboard, the amount of sizing should be adjusted as much as possible, and the speed of the machine should be increased in order to avoid the effect of excessive sizing or overheating temperature on the expansion and contraction of the paper fibers. The size of the sizing amount, usually the width of the glue line on the peak is 1-2mm (see Figure 2), and the specific amount should be based on the quantification of the end of the paper.

(to be continued)