How to control the moisture of carton paper
Main content
The strength of corrugated paper equipment directly affects the compressive strength of the paper box. In addition to factors that affect the durability of the wave layer, the main factor is the humidity control during the wave production. To control the water content of corrugated carton, the following aspects need to be paid attention.
1. The water content of base paper upon entering the factory must be strictly inspected
2. After entering the factory, the storage temperature of the base paper must be controlled at room temperature and the relative humidity shall not exceed 40%.
3. The base paper storage must be arranged vertically, and the ground will be treated against moisture.
4. Storage time of base paper should not be too long. This is an important condition to control the temperature and temperature during corrugated carton production to directly adjust the water content of corrugated base paper and ensure gelatinization. Therefore, when the corrugated board production line is in the range of 80m / min to 120m / min, the commonly used temperature must be controlled between 160 ° C and 180 ° C, and steam pressure should be controlled. The saturation of the boiler ranges from 0.9mpa to 1.2 MPa according to its conversion, so that the water content of corrugated base paper and single-sided corrugated water can be adjusted to ensure the gelatinization process. of adhesive. To ensure the durability and adhesion of corrugated carton, the formation of corrugated carton must be adjusted according to the different configuration of corrugated carton production line.
5. When the moisture of the base paper creases into the single-sided machine is controlled from 9% to 12%, the crease formation is ideal. When the humidity of the creasing media is higher than the above index, this can be solved by increasing the preheating area or reducing the speed of the creased paper. When the humidity of the creasing environment is lower than the above index, spray can be used to solve the problem. Next, through fast paper loading on the flyover conveyor belt, the water content of the base paper is better adjusted, the water content is more suitable, the number of stacking of single-sided corrugated sheets on the flyover should not exceed Many, but to ensure that the double-sided machine does not stop
6. The dryer temperature has a great influence on the moisture of the corrugated carton. The heating part of corrugated carton production line usually consists of three groups (or four groups). The number of heating plates is determined by the size of the heating plate and the speed of the corrugated carton production line, and each group is equipped with an independent control valve. To ensure that the moisture content of single-sided wave boards before entering the dryer is basically the same, this can be solved by adjusting the preliminary drying area of the single-sided wave board on the backpack dryer. The method of adjustment is: when the water content is too high, the preheating area increases; When the water content is too low, the pre-drying area decreases.
7. Because the corrugated carton manufacturing process takes a lot of heat, a part of the saturated steam will turn into condensate in the preheater and corrugated roller, which can be discharged through steam trap. To ensure normal condensate discharge, open the bypass valve before the steam trap every 4 hours for 3-5 minutes to ensure relative stability of temperature. The main components of the binder are corn starch, water, sodium hydroxide and borax. The viscosity, concentration and gelatinization temperature of the adhesive are different due to the different configuration and speed of corrugated carton production line. With the amount of glue, the water content of the waveboard also varies. When the amount of glue is large, the water content of the wave board is large, otherwise small. For single-sided and double-sided machines, the distance between the glue roller and the limited roller is usually 0.2mm - 0.25mm; The distance between the lower wavy roller and the glue roller of single-sided machine is usually 0.1mm-0. 2 mm; The distance between the double-sided roller (contact pressure bar) and the glue roller must be slightly lower than the height of single-sided corrugated cardboard by 0.05mm - 0.1mm. The upper clearance can be measured with a sensor ruler, but the two rollers must be parallel.
8. With the change of temperature and relative humidity (summer and winter), the amount of glue is also less, because the viscosity of the adhesive becomes thinner in the summer, the concentration can be adjusted by a suitable way of increasing the solid content, and a base paper with a high ring pressure index and poor moisture absorption can be used; Adhesion of adhesive in winter is poor, and adhesion of adhesive can be guaranteed mechanically by increasing the temperature of adhesive and carton.
