The corrugated box is made of moisture-proof, in addition to protecting the packaging from being soaked by water, it is mainly to prevent water from moisturizing the box itself.

Because the compressive strength and bursting strength of the carton will be greatly reduced after the carton is soaked in water, which will seriously affect the quality of the packaging. Shenzhen corrugated boxes are used for moisture-proof manufacturing, which is usually treated by coating waterproofing agent. Therefore, according to the function of the waterproofing agent, the manufacturing method of the moisture-proof carton can be divided into: temporary waterproofing treatment and permanent waterproofing treatment.

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Temporary Water Repellent

After the corrugated cardboard is treated with a temporary waterproof agent in the production process, it has a temporary waterproof function. According to the explanation of JISZ1537: when water falls on it for a short time, it will not get wet and form water droplets, which can prevent water from penetrating the cardboard. Temporary waterproofing agent treatment of cardboard technology has been used in major carton factories in my country in the past ten years. This waterproofing agent was originally introduced from Japan, and its Japanese literal name is "water pulling agent".

This coating was used on textile fibers in the early stage and was only used in the treatment of cardboard later. Therefore, most carton factories use the name of water pulling agent. The water pulling agent is a wax emulsion with a solid content of 48% to 51%. Its [sensitive word] feature is that it can be diluted with about 30 times of water when used, and then coated on the surface of the corrugated cardboard being formed. After drying at a temperature of about 150°C, the fibers on the surface of the paper have low surface tension due to the wrapping of vinegar, forming a surface layer that is not moist to water. When it encounters water, the water does not moisten the cardboard, forming water droplets to roll down, thus achieving the effect of waterproofing. However, the adhesion of wax to paper fibers is not good, especially when the water-drawing agent is diluted 30 times, its solid content is only 1.5+, and the fibers on the surface of the paper are only covered by wax in a thin layer. In addition, because the particle size of the wax in the wax emulsion is usually larger than that of the ordinary polymer emulsion, it is difficult to penetrate deep into the paper fiber. At the same time, the water-drawing agent is usually sensitive to chemicals such as alum, and it is usually very weak on the surface of the paper. The rice is quickly broken and deposited, so most of the wax particles in the water pulling agent only exist in a very thin layer on the paper surface.

Under the action of external friction force, the wax is easily rubbed off, exposing the fiber without wax wrapping, and the waterproof effect is greatly reduced. In order to enhance the adhesion of wax to paper fibers, there are usually rosin derivatives or carboxylated polymer emulsions in the water-drawing agent, which not only have good adhesion to paper fibers, but also have good compatibility with wax. In this way, their addition can promote the adhesion of the wax to the paper fiber. At the same time, if the wax is modified, such as oxidized and base-based, it also has a similar effect, which can increase the adhesion of the wax to the paper fiber. However, it must be pointed out that even with the addition of these measures, the water-extraction agent does not form a waterproof film at such a concentration. This usually renders this waterproof surface useless. This is why this type of carton coated with water-extraction agent is designated as a temporary waterproof carton. At present, the water-extraction agent has been widely used in some carton factories and has become a basic process.

The extensive use of coated water-extraction agents is mainly affected by the following four aspects: the price of the water-extraction agent and the machine-coatability; There is no adverse effect on the recycling of the carton; the waterproof effect of the water-extraction agent is completely acceptable for the use of ordinary cartons.

However, it must be pointed out that for cartons used in some special environments, such as cartons in Dongku, cartons that need to be stored in a high-humidity environment, and cartons that need to be shipped by sea, you must be cautious when using water-draining agents. . In practice, it has been found that there are cases where cartons coated with water-draining agent are deformed after being taken out of the freezer, causing economic disputes. Therefore, when recommending customers to choose waterproof treatment, the use environment of the customer's carton should be fully considered.