Low-quantity Corrugated Box Production Quality Problems and Corresponding Countermeasures II

(II) Production process factors and technical requirements for quantitative cardboard

The strength and quality of the low-quantity corrugated board are the most direct factor in the equipment and operation of the board production line.

First of all, the factors of the cardboard production line equipment are the preconditions for the production of high-quality, low-quantity corrugated cardboard. This mainly depends on the accuracy and controllability of the device. Such as corrugating roll, rubber roller, pressure roller accuracy and adjustment of the gap, as well as the pressure roller or touch bar parallelism and the extent of the jump, the parallelism of the hot plate, etc., will have a direct impact. Gang's quantitative corrugated board production quality. If the accuracy of the corrugating roll is mainly the precision of manufacture or repair, it cannot reach O. Below 04mm, or the bearing's runout error is greater than O. 05mm, with about 90g of corrugated paper production, the first reflected is the wave-shaped molding is not good, corrugated deflection or cardboard thickness is not enough, will directly affect the cardboard side pressure and compressive strength. If the collimator gap parallelism can not be controlled at O. Below 05mm, the amount of glue on the paperboard will be uneven or too large, and the paperboard will have the phenomenon of blemishes, pitting and warping. The same phenomenon will occur if the parallelism and runout of the pressure roller or contact bar exceed a certain range. The controllability is whether the device can flexibly control the required parameters. Such as the amount of glue on the size of the temperature and the size of the pressure can be automatically adjusted and so on. To ensure the production of low-quantity corrugated board, we must consider whether the equipment's own performance and parameters can meet the requirements. Therefore, higher requirements are also placed on the technical performance and configuration system of the cardboard production line.

Second, production line adhesives are another important factor in the ability to produce high quality, low volume corrugated board. The requirements for the production of low-quantity corrugated paperboards for adhesives are mainly high adhesion and moisture resistance. Therefore, the formulation and production process of adhesives must be adjusted. Followed by the amount of glue, to deal with the amount of glue to effectively control. On the basis of ensuring the bonding strength, the amount of glue should be reduced as much as possible, and the amount of glue is too large, which is a major factor in the occurrence of paper pockmarks and facial paper blemishes and rib marks. The author suggests: The viscosity of the adhesive can be properly increased, generally controlled at 60-70S (coating a 4 cups), and the amount of glue on the control of about 0.2mm is appropriate. For the adjustment of the design and processing of the squeegee roller, it is better to use a hexagonal or round type and a hemispherical concave design with a mesh size of more than 100 meshes, so as to ensure the evenness of the glue amount.

In addition, the corrugated waveform is an important factor in ensuring the strength of low-quantity corrugated cardboard. This mainly depends on the characteristics of each wave type, and what kind of wave shape will directly affect the strength and control glue volume of the low quantitative corrugated board. The author proposes that V waveforms should be used for the production of low-quantity corrugated board B or E and below, while A or C should be UV-waved and should be designed close to the V shape. This is mainly to make the paste line can be controlled within 0.8-7.2mm, to avoid cardboard penetration and to maintain the triangle supporting force of corrugated, so as to ensure the strength of the cardboard.

Of course, the technical factors of production operations will also have a significant impact on whether high-quality, low-quantity corrugated cardboard can be produced. Mainly the adjustment and control of raw paper moisture, production temperature, production speed and pressure:

â–  The raw paper moisture should be appropriate. For low basis weight papers, especially corrugated paper, the water on the machine should not be too high or too low, the water content is too low, the base paper will be brittle, the paper breakage will be serious, and the paperboard will be damaged. Instantly absorbing moisture in the adhesive affects the adhesion, and after too low it absorbs moisture faster causing board, especially single-sided board variations, to affect adhesion and warpage. If the moisture content is too high, the forming of the low-quantity corrugated cardboard will be poor, resulting in a phenomenon of flat slanting and affecting the strength of the cardboard. Therefore, the on-board moisture should be controlled at 5-8%, and when pasting, the tissue paper should not be preheated as much as possible, because the low basis weight of the base paper itself is generally lower, and then the water after preheating is used. Further evaporation will not only affect the bonding (especially the middle clamp adhesion) during the sticking and drying process, but will also cause the board to warp, and it is an important factor for producing the rib marks and the liner marks.

The production of low-quantity corrugated board can not be too high temperature, it is recommended to control between 150 ~ 160 °C. When drying, it is best to open only the first two sets of hot plates, too high temperature will produce similar phenomenon with the water is too low.

The production speed should generally be controlled at about 80-1 20m/min. If the vehicle speed is too slow or too fast, it will have an adverse effect on the cardboard, especially the warpage of the cardboard.

In terms of pressure, whether it is the working pressure of the single-side machine rollers or the pressure of the blanket press roller, it must be properly controlled. Otherwise, the cardboard may be crushed or flattened. This needs to be based on the equipment. Specific performance and controllability are adjusted.
(to be continued)