Analysis on the current situation of corrugated bo

Analysis on the current situation of corrugated boxes for exported fruits

the packaging materials used in fruits all over the world include wooden boxes, bamboo baskets, rigid plastics and foamed plastics, cardboard or corrugated cardboard. Corrugated box is the most widely used packaging material at present because of its characteristics

the structure of corrugated board includes two-layer corrugated board, three-layer corrugated board and five layer corrugated board. The two-layer corrugated board refers to a piece of lining paper and a layer of corrugated base paper, which are only used as spacers and liners in fruit packaging. Three layer corrugated board is also known as single corrugated board. A layer of corrugated base paper is sandwiched between two layers of box board paper. It is generally used for internal packaging, and it can also be used for checker board or layered liner. Five layer corrugated board is also called double corrugated board, and two layers of corrugated base paper are sandwiched between three layers of carton paper. Five layer corrugated boxes have good compressive strength and are usually used for export packaging

when designing corrugated boxes for fruits, we should not only consider the needs of fruits, but also consider the requirements of the market, such as the quantity and quality of materials used, as well as the combination methods, including packaging, sealing, handling, palletizing, stacking and other specific issues

the corrugated width and height will affect the pressure, flat compression strength, edge compression strength and rupture strength of corrugated board. Type a corrugated and type C corrugated are suitable for fruit packaging because of their high compressive strength, stiffness and good cushioning performance. E-type corrugated is mainly used for small folding cartons. It provides a flat surface for high-quality printing and labeling patterns. The outer lining paper needs high tensile strength, while the inner lining paper needs good stiffness. Recycled paper is cheaper than imported paper, but its tensile strength is low

starch adhesive is ideal for checking whether the computer is equipped with a printer under humidity conditions. All export packages must use waterproof adhesive. Waterproof adhesive is essential to prevent the delamination of paperboard and packaging failure. Special waterproof adhesives can be obtained by adding waterproof chemicals to starch

vertical pressure in stacking is usually the most important aspect of fruit packaging. The cracking of the bottom of the box will not only damage the packaged fruit, but also spread the whole package. Therefore, there will be enough vertical corrugations on the top of the box and the edge of the cardboard to have sufficient compressive strength

in many developing countries, pallets have been widely used in the transportation of many commodities, including fruit packaging. The package stacking on the pallet can form a containerized cargo suitable for mechanized handling. The advantage of handling pallet packaging is that the labor cost in handling is greatly reduced; Reduced transportation costs; It is conducive to protecting goods and reducing losses; It is suitable for mechanized handling, with fast speed; It can be effectively used by increasing the stacking to prevent dust from entering the internal storage space, and the tray also promotes the use of standard sizes

traditional pallets are usually made of wood, but now they are also made of cardboard, plastic, metal or mixed materials. The simplest wooden pallet is designed in two-way forklift and four-way forklift. Four way forked pallets are difficult to manufacture, but they are needed by both transporters and the market. Many countries, including all European and North American countries, use international standard pallets. The size of this tray is 1.2 meters × 1 meter, and the size of other widely used pallets is 1.2 meters × 0.8m and 1.1m square × 1.1 meters

marine refrigerated containers are often used for fruit export. Effective space utilization in the container prevents high transportation costs. Shipping containers have standard actual dimensions, which are 6.1m or 12.2m long, 2.44m wide and 2.44m or 2.59M high respectively. The internal dimension changes with the structural method and refrigeration equipment. The minimum internal width is 2.22 meters, which enables any kind of tray system to be used. Loose packaging can be stacked in the top space, which changes with the structure of the container. If the packages are stacked loosely, they should be effectively suitable for shipping containers, suitable for 1.1-meter square pallets. Any package designed according to this pallet can certainly carry shipping containers, and the minimum width of this kind of container is 2.25 meters

generally, according to some packages that importers particularly like, we can understand the performance of their imported packages and meet the needs of retailers. Net weight is very important. Sometimes the size of the package must be changed to meet the weight requirements. Years of experience has proved that the ratio of length to width is 1.5:1, which is the most acceptable for importers. The ratio of length to width is close to 1:1, which is not only unpopular in appearance, but also difficult to apply to pallets. In addition, the packaging with length: width: height of 2:1:2 is not stable in stacking, although it uses the most materials. This increases the problems in transportation and storage. Therefore, it is not practical to consider the problem only in saving materials

the packaging of fruits should conform to the mechanization of packaging, so cartons must also be designed according to the requirements of the machine. Generally speaking, the volume of boxes packed by machines is larger than that packed by hand

air circulation can reduce the temperature of fruits, so corrugated boxes containing fruits are generally opened with pores. The air passing through the vent can also prevent the heat generation of fruits in the oxidation process. Vent is very important for cold storage of fruits, especially compressed air cold storage. Pores promote the evacuation of ethylene produced by fruits, but are not very important for the conversion of oxygen and carbon dioxide. Because these gases can flow through cardboard. If a plastic bag is used in the carton to reduce the oxygen content in the air around the fruit, the vent will almost have no effect. On the contrary, high humidity will be generated in the plastic bag to accelerate the decay of the fruit

the diameter of the vent hole is usually 25~30 mm, and the total area of the hole cannot exceed 3~5% of the whole packaging area, unless compressed air freezing is required. If there must be a handle hole, the vent hole should be placed on the top of the box wall. Two smaller finger holes occupy 30 mm of space, which is smaller than the pressure reduction caused by one handle hole, and also reduces the risk of finger damage to fruit. The number and size of air vents should be determined according to the physical conditions of the fruit, such as the shape of the fruit, the storage conditions of the box, etc

the compressive strength of corrugated boxes is affected by humidity, which is caused by many factors. But it is mainly water vapor in the air. Other sources, such as water vapor on the surface of the package when it is removed from the cold storage in rainy days, and water evaporated from the fruit inside the corrugated box. As the humidity in the paperboard increases, the compressive strength decreases rapidly. Therefore, waterproof treatment should be adopted to maintain the compressive strength of the box. The surface coating can prevent rain and condensation, but it can only relatively reduce the absorption of water vapor. The corrugated box treated by impregnation can prevent moisture for a long time, and can also improve the compressive strength and stiffness, especially the compressive strength of low gram weight or poor quality paperboard

if the moisture resistant agent is added to the pulp in the production process, the waterproof performance of the paper can be improved. The surface of the box and paper can also be waterproofed by pouring or dipping wax, or using a certain high polymer coating. The paperboard is immersed in dissolved wax, and the wax is coated on the corrugated paper core and layer paper, which can be almost completely waterproof

the quality of the coating required varies with the application method of moisture-proof agent. If the corrugated board is coated with wax and treated with spray, the amount of wax is 30 grams per square meter; In case of immersion treatment, 200-300 grams per square meter. The moisture-proof treatment of resin and high polymer is different, but it is usually 10-20 grams per square meter

sealing is a simple and important procedure. The usual method is to use liquid adhesive, tape adhesive, staples, and packing tape. Hot melt adhesive is suitable for continuous mechanized operation with high efficiency and is suitable for two-layer fruit packaging. Polypropylene plastic packing belt is usually used for fruit packaging, which can easily and tightly tie the packaging. The sealing tape used for fruit packaging is transparent or opaque pressure-sensitive tape, which is convenient to use and moderate in price

introduce several kinds of padding materials for fruit packaging:

wrapping paper should be soft, smooth, clean, micro free and flexible. Chemical treatment is necessary to prevent mildew, and diphenyl has been banned in many countries. Wrapping paper can prevent fruit from vibration damage, reduce water loss, and reduce the speed of mildew

single or double sided paperboard can be used as a partition to prevent mutual contact between fruits. When the cardboard partition is in the middle of the fruit, it can provide additional stacking strength for the package

pulp mold shallow plates of different sizes are suitable for fruits of different sizes. The plate should be tasteless and clean, and the color should not be printed on the fruit. Foam polystyrene mold shallow dish is used like pulp mold shallow dish. Thin PVC or plastic moulded shallow plates can also be made into different sizes and shapes to hold fruits and prevent them from being damaged by vibration

foamed plastic sheets, including soft foam polyethylene, polyurethane or polystyrene, can be used as thin sheets, thick spacers or lattice sleeves. Foam polystyrene sheet can absorb vertical impact force and prevent impact between box edges

plastic bubble liner is made of plastic film filled with air, conventional scenic spot fatigue strength theory nominal stress method and local stress-strain analysis method. It is used as liner or placed on fruit to prevent vibration damage of fruit. The plastic film lining, with a thickness of 002~004 mm, is used as a lining bag to prevent moisture loss, control the concentration of oxygen and carbon dioxide, and prevent fruit decay

to ensure that the fruit can reach the destination in good conditions, we must pay attention to the selection of packaging materials that will not shrink or swell during normal stacking; Handle carefully during harvesting, packaging and transportation; Carefully select padding and protective materials to ensure that the fruit is placed in a fixed position and will not rub against each other; Do not over pack; Stacking is not allowed to exceed the designed height; A cushion should be placed between the fruit and the top of the box to prevent the fruit from moving. (Zhu Min)

source: Shanghai packaging