The purpose of waterproofing and moisture-proof of corrugated cardboard boxes is actually to maintain the compression performance of cartons. After the water erosion of paper, the corrugation will collapse and soften, which will greatly reduce the packaging safety. However, most people understand that carton waterproof is only the problem of water proof after carton forming, but it ignores the original water content problem in carton paper. In fact, it is also important to control the water content of corrugated paper to improve the safety performance of corrugated packing box. The control of the water content of corrugated cardboard should be emphasized in the following aspects.
The water content of 1. corrugated paper should be inspected in strict accordance with the standard of GB13023-91.
After 2., the storage temperature of corrugated paper should be controlled at normal temperature, and the relative humidity is not more than 40%.
3. corrugated paper should be stored vertically stacked stacking, the ground should do moistureproof processing.
The storage time of 4. corrugated paper should not be too long. Controlling the temperature and temperature in the process of corrugated paperboard production is an important condition to directly adjust the water content of corrugated paper and ensure the gelatinization of the adhesive. Therefore, when the corrugated cardboard production line at 80 m / min to 120 m / min, the temperature should be controlled between 160 to 180 DEG C, should be controlled in 0.9Mpa-1.2Mpa according to the conversion of the boiler water saturated vapor pressure, so as to adjust the corrugated and single-sided corrugated cardboard, and guarantee adhesive paste.
In order to ensure the strength and good adhesion of corrugated cardboard, the formation of corrugated cardboard should be adjusted according to the different configuration of corrugated cardboard production line.
1. when the water content of the corrugated paper into the single plane is controlled between 9% and 12%, the corrugated forming is the most ideal. When the moisture content of corrugating medium is higher than the above index, it can be solved by increasing the preheating area or decreasing the speed of the vehicle. When the moisture content of corrugating medium is lower than the above index, it can be solved by spray. The author thinks, single-sided corrugated cardboard paper by fast under the overpass on the conveyor belt for positive type and accumulation of the same distance, adjust the water base paper and corrugated paper is better, its water content is appropriate, the number should not be single-sided corrugated cardboard on the bridge piled up too much, but in order to ensure the double machine downtime, in the paper for the single machine when the accumulated single-sided corrugated cardboard on the bridge number can be appropriately increased.
2. the temperature of the dryer has a great influence on the water content of corrugated cardboard. The heating section of corrugated cardboard production line is usually made up of three groups (including four sets). The number of heating plates is determined by the size of heating plate and the speed of corrugated cardboard production line, and each group has independent control valves. In order to ensure that the water content of the single side corrugated cardboard before entering the dryer is basically the same, it is possible to adjust the preheating area of the single side corrugated cardboard on the three preheater. The adjustment method is as follows: when the water content is too high, the preheating area is increased; when the water content is too low, the preheating area is reduced.
3. because of the production process of corrugated cardboard packaging box to take a lot of heat, a partially saturated steam in the preheater and the corrugated roller will become condensed water, usually can be discharged through the trap, in order to ensure the normal discharge of condensed water, the author suggests that, every 4 hours to open the bypass pipe valve steam trap before 3 minutes to 5 minutes, to keep the temperature relatively stable. Good control of the gelatinize making corrugated cardboard is commonly used in corn starch adhesive, its main components are: corn starch, water, sodium hydroxide and borax, the corrugated cardboard production line configuration is different, the different speed, concentration, viscosity, gelatinization temperature of prepared adhesive is also different. With the size of the coating, the water content of corrugated cardboard also changes. When a large quantity of plastic, corrugated cardboard moisture is high, and vice versa. The gap between the coater and the rubber roller of the single machine and the double faced machine is generally 0.2mm to 0.25mm. The gap between the corrugating roller and the rubber coated roller is generally 0.1mm to 0.2mm, and the gap between the double-sided press roller and the rubber roller is slightly lower than that of the single side corrugated board height from 0.05mm to 0.1mm. The space available feeler, but should ensure that the parallel between the two rollers.