Cardboard Problem Solving - Control of Water Content

Four control the moisture, temperature, glue to improve the cardboard problem

Corrugated board strength directly affects the compressive strength of corrugated boxes. Excluding the factors affecting the strength of the corrugated board, the key factor of the corrugating medium's ring pressure index is the control of moisture in the corrugated board production process. For the control of the water content of corrugated board, the author believes that the following aspects should be controlled.

â–  Control the moisture of corrugated paper

The water content of the corrugated paper into the factory should be in strict accordance with the GBl3023-97 standard.

After entering the factory, the storage temperature of the corrugated base paper should be controlled at room temperature and the relative humidity should not exceed 40%.

The corrugated paper should be stored stacking vertically, and the ground should be protected against moisture.

Corrugated paper storage time should not be too long.

â–  Control the temperature in the production of corrugated board

The temperature is an important condition for directly adjusting the moisture content of the corrugated paper to ensure the gelatinization of the binder. Therefore, when the corrugated board production line is between 80m/min and 120m/min, the commonly used temperature should be controlled between 160°C and 180°C, and the saturation steam pressure of the boiler should be controlled at 0.9Mpa-7. .2Mpa, this can not only adjust the moisture content of corrugated base paper and single-faced corrugated board, but also ensure the gelatinization of adhesive.

In order to ensure the strength and good adhesion of the corrugated board, the corrugated board should be adjusted according to the configuration of the corrugated board production line.

The corrugated molding is ideal for controlling the moisture content of corrugated paper entering single-faced machines between 9% and 12%. When the corrugated paper moisture content is higher than the above indicators, it can be taken to increase the warm-up area or reduce the speed; when the corrugated paper moisture content is lower than the above indicators, spray can be taken to solve. The author believes that single-sided corrugated paperboard through the rapid transfer of paper on the bridge conveyor belt is positive ∞ type and consistent deposition distance, the original paper and corrugated paper moisture adjustment is better, the water content is more appropriate, single-sided corrugated cardboard stacked on the bridge The amount should not be too much, but in order to ensure that the double-sided machine does not shut down, the number of single-sided corrugated cardboard stacked on the flyover can be appropriately increased when the single-sided machine is changed paper.

The temperature of the dryer has a great influence on the water content of the corrugated board. The heating section of the corrugated board production line usually consists of three groups (four groups also). The number of heating plates is determined by the size of the heating plate and the speed of the corrugated board production line, and each group is provided with an independent control valve. To ensure that the moisture content of the single-faced corrugated cardboard before entering the dryer is basically the same, the size of the preheated area of ​​the single-sided corrugated cardboard on the triple preheater can be adjusted. The adjustment method is: when the water content is too high, the preheat area increases; when the water content is too low, the preheat area decreases.

As the corrugated board production process takes away a lot of heat, a part of the saturated steam will become condensed water in the preheater and the corrugating roll and can be discharged through the steam trap. In order to ensure the normal discharge of the condensed water, the author suggests that every 4 Open the bypass piping valve in front of the trap for 3 minutes to 5 minutes to ensure a relatively stable temperature.

The corrugated board is usually made of corn starch adhesive, and its main components are: corn starch, water, sodium hydroxide and borax. Due to the different configuration of the corrugated board production line, the speed is different, and the adhesive viscosity, concentration, The gelatinization temperature is also different. With the amount of glue applied, the moisture content of the corrugated board will also change. When the amount of glue is large, the water content of the corrugated board is large, and vice versa. For the single-sided machine and double-sided machine, the gap between the rubber-coated roller and the rubber-limit roller is generally 0.2mm-0.25mm; the gap between the single-sided machine under the corrugating roller and the rubber-coated roller is generally 0.1mm-0.2mm; The gap between the double-sided press roller (touch bar) and the coating roller should be slightly lower than the single-sided corrugated board height of 0.05mm-0.1mm. The gap can be measured using a feeler gauge, but the two rollers should be parallel to each Other.

With the change of temperature and relative humidity (summer and winter), the amount of rubber applied is also small. The reason is that the viscosity of the adhesive in the summer becomes thin, and the concentration can be adjusted by appropriately increasing the solid content. Base paper; poor adhesiveness of winter adhesives, which can increase the temperature of the adhesive and ensure good fluidity of the adhesive.

In addition to the above-mentioned factors affecting the strength of corrugated board, the responsibility of operators is enhanced and the operator's skill level is improved so that each operator can observe carefully and carefully adjust and strictly operate according to the process requirements to produce high Quality corrugated cardboard.

Author: Song Zhihua Packaging Machinery Co., Ltd. Qingdao JU

Corrugated Carton, July 2005 issue