Carton defects

Any carton factory does not want the carton to be defective. It pays attention to the following aspects:

1) The corrugator must maintain a good mechanical condition as much as possible;

2) Check the carton regularly to find out the mechanical problems in time;

3) The operator needs to understand the properties of the paper and the effect of adhesive moisture on the paper;

4) The adhesive formulation should be compatible with the equipment and the paper used.

Inadequate bonding

Insufficient sizing is caused by insufficient sizing; the core paper has too strong absorption capacity, excessive heating in the preheating section, or improper adhesive.

When the corrugating machine is running very slowly and the preheater is not adjusted, the problem of insufficient adhesion is often generated. At low speed, especially when the adhesiveness is low, and the used sizing roller is relatively smooth, the coated starch adhesive will come off, so that the adhesive is difficult to penetrate into the interior of the thermal paper, resulting in only the surface Bonding. When the adsorption of the core paper used is too strong, the water is quickly absorbed onto the dome of the core paper, leaving little residue on the glue line to make the tissue wet and starch gelatinous.

When the adhesive is not suitable, problems first occur at the edges. The adhesive seems to be soaked. The main reason is that the glue formed when the starch is gelatinized is too thin, and the glue is completely soaked from the glue line. The reason may be that the solid content is too low, or it is affected by bacteria and mold. Pollution.

Large area of ​​open plastic or air bubbles

It is common for iodine staining tests to open glue after starch bonding. The problem is that because the initial tack force is not strong enough, the pressed corrugated medium cannot be pulled out from the pressure roller. The force required to pull out the corrugating medium depends on the type of paper, the cleanliness and smoothness of the corrugating roll, and the angle at which the belt is conveyed to the first-stage drive roll. The initial adhesion depends on the formulation of the adhesive and the sizing. Rate, press roll and pressure roll temperature, face paper temperature, and extrusion force. In general, the higher the binder solids content, the less bubbles and other problems occur.

Incorrect installation of the blade can also cause foam problems.

After the longitudinal cut, the second face paper loose edge

When loosening high-height cardboard, loose edges are a major problem. The reason for this is that due to the separation of the tacking layer by the cutter, improper installation of the knives aggravates the occurrence of loose edges. The use of a special adhesive for the bonding of the second facial tissue can reduce the occurrence of loose edges. The loose edge problem is generally caused by the fact that the edge of the tissue paper is too wet, or because the hot plate accumulates dust and debris, the crucible is deformed as it passes through.

Cockroach phenomenon

The cause of this problem is due to the excessive amount of glue applied, and the reason for the excessive glue coating is due to the too strong adsorption of the core paper or the tissue paper, or too rough, and the poor water-containing ability of the coated adhesive. If the core paper has a strong adsorption and the starch has poor water-retaining ability, the moisture immersed in the crucible wall is difficult to remove, and the paperboard appears soft and loose.

Warping

Warpage is the most common defect in corrugated board, adding to the factory's troubles, at least the cost. Automatic palletizers are not suitable for stacking warped cardboard. Modern production lines cannot produce warped corrugated cardboard at normal speeds, and users are not allowed to warp cardboard.

Ensure that the two processes of the paper are smooth, so that when the single corrugated sheet is bonded to the second sheet of paper, the balance can be avoided and warping can be avoided. Use the same strength and moisture content of the paper, will not cause warping.

The root cause of warpage is when the paper expands when it is wet and shrinks when it dries. If the binding occurs when one side of the paper is wet compared to the other side, the paper actually begins to warp toward the wetter side as the wet side loses moisture and shrinks. In addition, corrugated paper also has an effect on warpage, but it is less important.


Author/(Shen Jia)

Source: Shanghai Packaging