Corrugated cardboard boxes are made to prevent moisture. In addition to protecting the packaging from water, it is mainly to prevent the water from infiltrating the box itself.
Because the carton's compressive strength and bursting resistance will be greatly reduced after being soaked in water, this will seriously affect the quality of the packaging. Corrugated cardboard boxes are made of moisture-proof products, which are usually solved by applying waterproofing agents. Therefore, according to the action of the waterproof agent, the manufacturing method of the moisture-proof carton can be divided into: temporary waterproof treatment and long-term waterproof treatment.
Corrugated paperboard has a temporary waterproof function after being treated with a temporary waterproof agent in the production process. According to the interpretation of JISZ1537-: when the water falls on it for a short time, it will not become wet and form water droplets, which can prevent the water from penetrating the cardboard. Temporary waterproofing agent processing paperboard technology has been applied in major carton factories in China in the past decade. This kind of waterproofing agent was originally introduced from Japan, and its Japanese name is "water-removing agent".
This coating was used on fabric fibers in the early days, and was later used in the processing of cardboard. Therefore, most of the tree carton factories use the name of water pulling agent. The water-removing agent is a wax emulsion, the solid content is generally: 48% to 51%, its biggest 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 150 Drying at a temperature of about ℃, the paper surface fibers have low surface tension due to the vinegar wrapping, forming a surface layer that does not wet the water. When encountering water, the water does not infiltrate on this cardboard, forming water droplets to roll off, thus achieving the waterproof effect. However, the adhesion of wax to paper fibers is not good, especially when the water-extracting agent is diluted 30 times, its solid content is only 1.5 ~, only a very thin layer of fiber on the surface of the paper is wrapped by wax. In addition, because the particle size of wax in wax emulsion is generally larger than the particle size of normal polymer emulsion, it is difficult to penetrate deep into the paper fiber. At the same time, the water-removing agent is generally sensitive to chemicals such as alum, which is often very fast on the paper surface The emulsion breaks down and settles down, so most of the wax particles in the water-removing agent only exist in a very thin layer on the paper. Under the effect of external friction, the wax is easily rubbed off, exposing the fibers that are not wrapped by the wax, and the waterproof effect is greatly reduced. In order to enhance the adhesion of wax to paper fibers, there are often rosin derivatives or carboxylated polymer emulsions in water-removing agents, which have good adhesion to paper fibers and good compatibility with wax. In this way, the addition of them can promote the adhesion of wax on paper fibers, and at the same time, if the wax is modified, such as oxidizing and matrixing, it also has a similar effect, which can increase the adhesion of wax to paper fibers. However, it must be pointed out that with these additions, the water-removing agent formed at this concentration is still not a waterproof membrane layer, so when encountering friction, such as the carton during transportation and stacking, friction will often Make this waterproof surface useless. This is why such cartons coated with water-repellent agents are designated as temporary waterproof cartons. At present, water pulling agents are widely used in some carton factories and have become a basic process. This is mainly due to the following four aspects: the price and machine coatability of the water-removal agent; the water-removal agent maintains the true color of the paper and is in line with the current mainstream returning to nature; the water-removal agent has no adverse effect on the recycling of the carton; The waterproof effect of the liquid agent is fully competent for the use of general carton. However, it must be pointed out that the carton used in some special environments, if necessary; the carton of the East Warehouse, the carton that needs to be stored in a high-humidity environment, and the carton that needs to be shipped by sea, you must be cautious when using the water remover. In practice, it has been found that cartons coated with a water-removing agent have been deformed after being taken out of the freezer, causing cases of economic disputes. Therefore, when recommending what waterproof treatment the customer adopts, the use environment of the customer's carton should be fully considered.
In addition, the raw materials and preparation processes of different brands of water pulling agents are often different. There are some differences in the water ratio. It is important to master this suitable water ratio when using it. If the water ratio is too high, the water pullout will be significantly reduced, and the waterproof effect will not be achieved; if the water ratio is too low, dark waxy oil spots are often formed on the cardboard surface, which damages the appearance of the cardboard.
