Manufacture of moisture-proof carton--moisture protection method (I)

Second, moisture-proof carton production program

In addition to protecting the packaging from moisture, water is prevented from being infiltrated by the water. As the carton is wetted by water, the compressive strength and bursting resistance of the box will be greatly reduced, which will seriously affect the quality of the packaging. Corrugated boxes for moisture production, usually coated with waterproof agent to solve. Therefore, according to the effect of the water repellent agent, the manufacturing method of the moisture-proof carton can be divided into: temporary water repellent treatment and permanent water repellent treatment.

(I) Temporary moisture prevention methods

Corrugated cardboard has a temporary waterproof function after it is treated with a temporary water repellent during the production process. According to the interpretation of JIS Z 1537-1989, when water falls on it for a short time, it does not wet and salty water droplets can prevent water from penetrating the cardboard. Temporary water repellent treatment cardboard technology has been applied in all major carton factories in China for the past ten years. This water repellent was originally introduced from Japan and its text surface was "water pick-up agent." This type of paint was used on fabric fibers early on and was later used for cardboard processing. Therefore, most tree carton manufacturers use the name of the water picking agent.

Pulling agent is a wax emulsion, the solid content is generally 48% -51%, its most significant feature is that it can be diluted with about 30 times of water in use, and then coated on the surface of the forming corrugated board, through 150 The temperature of about °C is dry, and the surface fiber of the paper has a low surface tension due to the wrapping of vinegar and forms a surface layer that does not wet the water. When it encounters water, the water does not infiltrate on the cardboard, forming a drop of water and falling down, thereby achieving a waterproof effect.

However, the adhesion of wax to paper fibers is not good, especially when the water extractant is diluted 30 times, its solid content is only 1.5-1.7, and only a thin layer of paper surface fiber is covered with wax. In addition, wax size in wax emulsions is generally larger than that of common polymer emulsions, and it is difficult to penetrate deep into the paper fiber. Simultaneously, the water pick-up agent is generally sensitive to a class of chemicals such as alum, and is often fast on the surface of paper. The emulsion breaks down and precipitates, so most of the wax particles in the pipetting agent exist only on the thin layer of paper. Under the effect of external friction, the wax is easily rubbed off, leaving no wax-wrapped fibers, and the waterproof effect is greatly reduced. In order to enhance the adhesion of the wax to the paper fiber, there are often rosin derivatives or carboxylated polymer emulsions in the water pick-up agent, which have good adhesion to the paper fiber, wax and good compatibility. In this way, their addition promotes the adhesion of the wax to the paper fibers, and at the same time, if the wax is modified, such as oxidation or basification, it also has similar effects and can increase the adhesion of the wax to the paper fibers. However, it must be pointed out that the increase in these measures, the concentration of the water pick-up agent formed at this concentration is still not a waterproof film layer, so when it comes to friction, such as the carton in the handling, stacking process encounters friction, often will Make this waterproof surface useless. This is why a carton coated with a water-repellent agent is defined as a temporary waterproof carton.

Currently, picking agents have been widely used in some carton factories and have become a basic process. This is mainly due to the following four aspects:

Pulling agent price and machine coatability;
The water pick-up agent maintains the true nature of the paper, and is in harmony with the current mainstream of the return to nature;
Pulling agent has no adverse effect on the recovery of the carton;
The water repellent's water-repellent effect is perfectly adequate for general carton use.

However, it must be pointed out that cartons used in some special environments, such as cartons that require cold storage, require cartons that are stored in a high-humidity environment, cartons that require shipping, and care should be taken when using water removers. In actual practice, cartons that have been coated with water-drawing agents have been found. From the East Warehouse, the cartons have been deformed, causing economic disputes. Therefore, when recommending what kind of waterproof treatment, customers should fully consider the use environment of the customer's carton.

In addition, different grades of picking agents, their raw materials and preparation process are often different, with some differences in the water ratio, it is very important to use this appropriate water ratio. If the ratio of water is too high, the degree of water withdrawal will be significantly reduced and no waterproof effect will be achieved. When the ratio of water is too low, dark waxy oil spots will often form on the surface of the cardboard and damage the appearance of the cardboard.

(to be continued)