Friends in the paper 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 paper corrugated cartons. The entire paper cardboard is also soft. The face of evasive complaints, or even returns, fines, and compensation, etc., to solve the paper cardboard softening has become a top priority for the carton factory.
Below, Joybean Paper packaging and printing provides you with a package solution to solve the paper cardboard box softening.
1, Moisture resistance of paper and board
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%.
Solution
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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 original 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.
2, 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.
Solution
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The base paper warehouse is isolated from the outside 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.
3, storage environment
The cardboard after going offline shall be used to remove the vapors that have not been scattered to avoid the formation of condensation due to the temperature difference. The environment for storing cardboard or cartons shall be kept ventilated and ventilated. The cardboard cartons shall not be placed directly on the ground, and the pallets (pallets, splints) shall be used. . Pay attention to the space between each other during storage to facilitate ventilation and heat dissipation.
Solution
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It is recommended to use wood pallets, which can absorb the moisture on the ground, and the size is suitable for paperboard carton; keep the storage environment ventilated and breathable, and use the wrapping film for external protection, which can effectively reduce and isolate the phenomenon of weather softening.
Now many manufacturers have started to use dehumidifiers, and if they can ensure that the relative temperature of the warehouse is below 65%, the hardness of the cardboard will increase significantly.
4, transport environment
In the process of product delivery, some use convertible vans, and some use vans. In general, the latter is more able than the former to protect the cardboard board from drying out and avoid softening.
Solution
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It is recommended to use van trucks, which are also commonly used by major supply companies.
5, Carton processing technology
Paper corrugated cardboard should enter the next process as soon as possible after it goes down the line from the paperboard assembly line. The longer the cycle, the easier it is to absorb water in the air and soften it.
In addition, when performing printing, particularly multi-color printing or large-scale solid printing, it is easy to cause the carton to be softened due to the pressure of the printing plate.
Solution
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Minimize the dwell time of the carton during production and processing, and avoid exposing it to moist air for too long and soft. The workshop should also be properly isolated from the outside to avoid direct steam blowing into the workshop.
Before printing, try to ensure the hardness of the corrugated board, printing to avoid excessive pressure. The die-cutting process avoids the use of a round die-cutting process that has a great deal of damage to the flat press.
In short, the problem of the softening of the carton requires the end of the matter or the problem of moisture. Only by doing everything possible to prevent the cartons from absorbing water during raw paper storage, corrugated board processing, carton processing, warehousing and transportation, we can be hardened.
