Canned food is a common breed of military food. Canned food can be stored at room temperature for a long time, and has strong ability to withstand adverse external conditions. In the current sluggish canned food market, the military still has a soft spot for it. Canned packaging is divided into flexible packaging, hard packaging and semi-rigid packaging in between depending on its hardness. From the perspective of development trends, these three kinds of packaging have development prospects in military use.
1 Hard-packaged military foods have been developed from hard-packed cans. The ability of hard cans to withstand adverse external conditions is the most important advantage of hard cans. For example, rats have no way to hard cans, hard cans have lower requirements for external packaging, and are resistant to impact during storage and transportation. Hard cans are mainly used in group foods in field foods or in general foods according to the current situation of the military. The trend of hard can packaging in military use in the future is as follows: a. Easy open cover: As mentioned before, hard cans have the disadvantage of opening difficulties. In recent years, a number of easy-open lids have been introduced into military foods, such as the 962 cans with a diameter of 90 mm and the eight-treasure porridge cans with a smaller diameter. But this does not meet the requirements of military cans. Because the most used military cans are 1068 cans with a diameter of 100 mm. Due to technical reasons, such a large-caliber easy-open cover is still not enough in China. In addition, the easy-open cover also has technical problems such as easy breakage of the pull ring and uneven depth of the scribe line. Therefore, the study of easy-opening hard cans is one of the main directions for the development of military cans in the future. b. Shaped cans: The US military's T ration is actually a rectangular flat can, which is made of chrome-plated tinplate. The food is 3 kg. The T ration is actually a two-piece can consisting of a bottom and a lid. The can can be used as a cookware, can be placed on a fire or placed on a steam table to heat and keep warm; or can be used as a tableware instead of a dish bowl to improve the ease of use of military food. At the same time, it is also a storage container. At present, China does not have the ability to produce such large rectangular cans. Its technical difficulty is mainly due to the high scrap rate when sealing, which leads to high production cost and cannot be applied. c. Coating: Military cans have a shelf life of more than 3 years. Moreover, coatings having sulfur and acid resistance are required. At present, some military cans often have rusting of the can body.
2 Flexible packaging cans of soft packaging have been developed on the basis of hard cans. The main problem with flexible packaging is the ability to withstand poor external conditions, and the sealability is more susceptible to damage than hard cans. The foil packaging has a poor ability to resist wrinkles, and when the degree of vacuum is large, wrinkles generated in the bag are liable to cause pinholes. In addition, anti-rat is also an important issue. Soft-pack canned food is mainly used in individual foods in field foods according to the current situation of the military. If it is technically improved, it may also be used for collective food. Soft can packaging will develop in the following directions: a. Aluminum foil bag: Aluminum foil has good barrier properties, including gas and light. However, the anti-wrinkle ability is poor, and in the case of wrinkles, the aluminum foil is prone to breakage and the like. Improving the anti-wrinkle performance by compounding with other materials is a direction for future research. b. Composite material: A new flexible packaging bag is produced by compounding materials with high barrier properties, puncture resistance and high temperature resistance. This bag has an outstanding advantage over the aluminum foil bag, which can be heated in the microwave, but its shading is poor, and some measures need to be taken to make up. c. Heat sealing layer: In the production of soft cans, if the bag mouth is contaminated, such as oil stains, the sealing may not be tight, or the strength is reduced, this problem has a great impact on the production speed and has an impact on the product quality. At present, relevant experts are exploring new The heat sealing layer still has a good sealing strength in the case of oil contamination. This technological breakthrough will have a major impact on flexible packaging technology. d. Anti-rat: It is common for soft-packed cans to be bitten by mice. Especially in combat conditions, this is especially true for field foods stored in simple field warehouses. This situation severely limits the use of soft cans. This problem will be solved in the future by the strength of the packaging material or by adding the unpleasant odor to the packaging material. e. Natural degradation: In view of environmental requirements, development can naturally degrade flexible packaging materials.
3 semi-rigid packaging Semi-rigid packaging is a new type of canning material. Because it is between hard cans and soft cans, it takes advantage of both. Especially in terms of opening, it is better than hard and soft cans. The development of new semi-hard canned materials will be one of the future directions for the development of military cans. a. Aluminum-plastic packaging: used in some field foods of the foreign army. If sauce, cream and some condiments. Aluminum-plastic cans are a kind of gas-filled cans. Due to the vast territory of China, there is a large plateau. Gas-filled cans will produce physical fatness at high altitudes. In order for aluminum-plastic cans to be used in our military, it is necessary to solve this problem. b. Co-extruded packaging of multi-layer materials: This material uses EVOH as a barrier material and can withstand temperatures up to 121 °C. Since the plastic has good molding properties, it is easy to be formed into a grid shape, and the top is heat-sealed with a plastic composite material. Thus, there are several types of meals in a box. This is hard to do with metal cans. Domestic enterprises have tried out this kind of packaging materials, and we are going to conduct experimental research in this area in the future. This kind of packaging should be the most promising. Moreover, it will have good development value in the civilian market.