Deformation Optimum Solution--Solve Problems

Nowadays, the production process of corrugated cartons is more and more sophisticated, but there are still many quality problems in actual production. For example, in the case of squall deformation, it is mainly manifested in that there is no correct corrugation height, there is a very small height difference in the corrugation height, the corrugation is tilted to one side, or the left and right thicknesses are not uniform. This is due to the fact that, in addition to the deformation of the corrugating roll caused by the flaw, the main reason is that the moisture of the base paper is not uniform, the temperature of the heat roll is not enough, and the tension is not adjusted. In view of the importance of the distortion problem, the publication will focus on this issue, starting from the key point, and providing you with the best solution to the change of the farewell.

The problem of "see-saw" of a corrugated cardboard

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 the corrugated board. As a carton manufacturer, it should not only purchase qualified raw paper, but also observe different production situations during production and control it at any time. Otherwise, there will be quality problems such as paperboard slats due to improper production control. In general, the "see-saw" shape of corrugated cardboard generally includes: scratches "see-saw", inter-concave pit "saw-like", trailing marks, and black lines "saw-like".

The reasons are as follows:

Scratches "see-saw" Cause: Mainly due to sub-hotplates fail to adjust in parallel or between two hot plates.

The reason for the "defective" shape between the depressions is:

â—† The physical properties of the paper are not up to standard;
â—† too much paste, hot plate wear (high and low);
â—† Core paper has high and low defects;
â—† Face paper is too strong and heat is too high.

Indentation, black paper "sawboard" reasons:

â—†The glue roller pressure is too low:
â—† The amount of paste is too large, and the canvas pressure is too low;
â—† The amount of caustic soda is too strong to cause excessive penetration.

To solve this kind of problem, we should start from the following aspects:

â—† When using thin, low gram weight liners, pay attention to reduce the clearance between the roller and the rubber roller to reduce the amount of glue applied:
â—† When pressure is prevented from being applied to the tip of the tip and the liner, excess glue is squeezed out and adheres to both sides of the tip of the tip, forming a much wider glue zone on the gutter than actually required. The shrinkage shrinks as the glue dries. , The liner is pulled down on both sides of the tip, resulting in "see-saw";
â—† Note that the fiber direction of the paper should be parallel to the corrugation direction;
◆ The worn corrugating roller and tip radius increase, and the prominent corrugated fiber will absorb more glue, resulting in the phenomenon of “seesaw plate”. Replace the corrugating roller.

Of course, in addition to the above solutions, the water content of the base paper and the amount of glue applied also have a great influence on whether or not the corrugated board is washed. Next, we will focus on these two aspects and provide you with effective solutions.

The effect of raw paper moisture content :

When the board has a see-saw phenomenon, the first thing that should be taken into account is whether the operator has adjusted the main parameters of each key point as required. Such as cardboard tension control, single-sided steam spray on the wet and dry degree of corrugated paper to adjust and control issues. Often overlooked a very important factor - the moisture content of the base paper, it is often thought that slightly higher or lower moisture content is not a big problem, as long as the paper can be machine production, there will be no cardboard degumming on the line. Actually, the problem of the paper's retractability depends largely on the moisture content of the paper itself. For an approved base paper, the moisture content must be strictly controlled between (8±2)%. The linerboard paper is controlled at (9±2)%. Excessive moisture content will cause the paper fibers to expand and elongate due to excessive moisture ingestion; and too low moisture content is not conducive to paper bonding and molding. One point is particularly noticeable on the use of low basis weight raw paper.

As low-volume corrugated paperboard has the advantages of light weight and low price, today it is faced with rising international pulp market, it is widely advocated and promoted by carton manufacturers. However, due to the low basis weight of the base paper and the thinness of the paper, it is difficult to manufacture corrugated cardboard, and the surface of the paperboard is often sloppy or blistering due to improper adjustment of production. Causes the board to be uneven, and the printing effect is also affected by quality problems.

Effect 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. But also with the blistering phenomenon, this phenomenon occurs in the quantitative low base paper. The reason is mainly due to the excessive amount of adhesive sizing.

As far as corrugated board production is concerned, both the single-sided and double-sided machines have problems with the amount of glue applied. For single-sided machines, in the gluing mechanism, the rotational speed of the sizing roller on the mechanical design is slightly slower than that of the corrugating roller, so as to ensure that the sizing roller conveys a proper amount of adhesive evenly on the corrugation peaks. 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 too large and the amount of glue is too much, 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 exert a tensile force on the bottom paper. 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 sheet to shrink and distort. When a low basis weight paper is used, the low tightness cannot be achieved. Resistance to wave tension can easily cause shrinkage of the base paper.

Similarly, for the double-sided machine, when the low-precision paper is used, it will also cause the paper to shrink and deform due to the inability to resist the tensile force, resulting in uneven appearance, and in severe cases even blistering. Therefore, the only solution that can be used 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 stretching of the paper fibers. to. The size of the sizing amount is usually 1 mm to 2 mm in width of the glue line on the peak. The specific amount of paper should be based on the amount of paper.

(to be continued)