Friends in the carton industry have been chasing the buttocks for customers for a period of time each year and asked the same sentence: Why is it so soft! This problem is really troublesome and difficult to solve, because the fiber used in carton base paper is a kind of hydrophilic material and it is naturally hygroscopic. In wet weather such as the rainy season, when the relative humidity in the air is too high, the cartons are in direct contact with the air and will absorb the moisture in the air, resulting in the production of corrugated cartons, and the entire cardboard is also soft. The face of evasive complaints, or even returns, fines, and compensation, etc., to solve the cardboard softening has become a top priority for the carton factory.
Below, the “Packaging Zone” micro-editing provides you with a package solution to solve cartons softening.
Paper and board moisture resistance
Raw paper and corrugated paper, especially corrugated paper, have strong water absorption; paper is exposed to moist air for a long time, the price of water increases, and the lateral compressive strength of paper is significantly reduced. When the relative humidity is 85%, the ring pressure strength It will drop by 60%.
It is recommended to use a base paper with a better waterproof and dampproof effect, especially pitting. To test the waterproof effect of the base paper, the surface water absorbency of the base paper can be tested by Ke Boyi. When the surface water absorbency is below 50 g/m2 (60S), the waterproof and moisture proof effect is better. If you can not test the instrument, directly on the cardboard or corrugated paper sprinkle a few drops of water, wait 60 seconds after the paper dry, observe whether the surface of the paper after the penetration of discoloration, if not, it proved waterproof and dampproof effect is better.
In order to improve the surface water resistance of paper, paper mills usually need to increase the proportion of waterproof auxiliaries in the surface sizing starch paste in the papermaking process. Because the auxiliaries are expensive, the water-repellent base paper has lower water resistance than the base paper. To be higher than 50-100 yuan, the higher the lower the gram weight, the higher. Therefore, the carton factory needs to take the initiative to communicate with the customers of the carton and appropriately increase the price.
Corrugated board production process
The main means to solve the softening of the carton is to select a good material, followed by the production process. The factor that softens the carton is to absorb excess water. Therefore, during the production and processing of the carton, the moisture in the carton should be removed as much as possible.
The base paper warehouse is isolated from the outdoors as much as possible, absolutely avoiding the damp air from wandering freely inside the warehouse. When appropriate, install a dehumidifier in the warehouse to ensure that the relative humidity is below 65%.
When the base paper is in the warehouse, it will absorb the moisture in the moist air. When the machine is on, it should increase the preheating angle of the base paper on the drying cylinder. If the effect is still not good, it can slow down the speed and increase the steam pressure.
Increase the powder content when making the paste, reduce the amount of glue, can reduce the moisture of the carton. Increasing the borax ratio also improves the feel of the corrugated board.
Reducing the amount of board stacking on the overpasses and slowing down the speed, especially after the stacking of corrugated board is fully dehumidified.