1. Introduction: Metal packaging plays an important role in the process of food preservation. In order to achieve the effect of keeping fresh, we usually use ldquo; Canned & throughout; . In the past century, canned food has become an important part of the human diet in developed countries. Metal packaging has the dual function of preventing any external effects on food during heat treatment and storage, and has the function of marketing and information packaging. The basic requirement for this kind of tin packing is good tightness; Metal packaging is widely used in various industries, such as candy can packaging and coffee can packaging.
2. Metal packaging performance requirements: preservation and protection of the product, resistance to chemical action of the product, resistance to treatment and processing conditions, resistance to external environmental conditions, shelf display characteristics required at the point of sale, easy to open and simple/safe product removal, composed of recyclable raw materials.
Food is packaged in a variety of containers, some of which are made of all metals, while others have metallic ingredients. Different types of metal packaging include beer and soft drink cans, food cans, drums and aerosol containers; Open the tray, cap and lid (for example, the lid on the glass jar and the top of the bottle). LIDS (for example, containers for yogurt and butter).
4. Aluminum & bull; Aluminum is widely used as a food contact material. Aluminum alloys used in food contact may contain elements such as magnesium, silicon, iron, manganese, copper, and zinc. Aluminum and its alloys have high corrosion resistance. When exposed to air, the metal forms aluminum oxide films (Al2 O3). The film is colorless, tough and does not peel off, and few chemicals can dissolve it. Most dilute acids erode pure aluminum. The solubility of aluminum hydroxide is limited at neutral pH. However, the solubility increases significantly when pH is lower than 4.5 and higher than 8.5.
5. Steel & bull; The main types of steel used in food contact packaging are electrolytic tinplate (ETP) and electrolytic chromium/chromium oxide coated steel (ECCS). Electrolytic tinplate (ETP) is a cold-rolled low carbon sheet or coil coated with tin on both surfaces and applied in a continuous electrolytic operation. Tinplate can be coated differently when one surface is heavier than the other. The usual coating weight is 1 to 15.1 g/m2.
6. Steel & bull; For food contact applications, the most common alternative to electrolytic tinplate is ECCS (electrolytic chromium/chromium oxide coated steel), which has an equal weight of coating on both surfaces of the coil. The function of chromium coating is to prevent the air oxidation or sulfur pollution of food to steel, and improve the adhesion of paint. ECCS are always used with an additional organic coating (i.e. canned coating). Usually used in the manufacture of pull cans, cans.
7. Tin & bull; Tin can be thinly coated on steel used in metal packaging. It is applied electrolytically during the manufacture of ETP (electrolytic tinplate). The tin layer is corrosion resistant and in some cases is not coated as tin can act as an effective deoxidizer. However, the use of tin without tin plating is limited by the various possible interactions between the metal surface and the food, and is therefore mainly used for light fruits, such as in saline or tomato-based products.
8. Recycling of packaging metals; Metal manufacturers can easily re-melt aluminum - and steel-based packaging materials. Waste from the canning process can be returned by third-party merchants for recycling. The post-consumption metal packaging scrap is collected and, after automatic separation from other scrap, eventually returned to the metal manufacturer for re-melting. Aluminum and steel lose no quality during remelting, so they can be reused indefinitely to produce high-quality packaging materials. Some recovery processes allow the tin to be separated from the steel base before being remelted.
9. Canned & bull; There are distinct types of cans and cans (or LIDS) in nature. Jars full of food are always covered with LIDS, so packers and packers buy empty jars and LIDS and sew the LIDS onto the jars. The tin can consists of two or three separate components (& LDQuo; Two - piece jar. And & other Three-piece jar ; The three-piece tank consists of a cylinder, a top and a bottom, while the two-piece tank consists of a wall and a bottom and a separate top. They range in size from very small (a few grams) to catering package size (usually 2-10 kg of content).
10. Two-piece can (pulled can) & Bull; The pull can is made by unwinding the metal coil or by using a metal plate and a stamping plate, usually coated on both sides of the metal substrate, usually using a high pressure press to move the disks. Cup & throughout; In the shape of a short metal beaker, this is the first stage of distortion in canning.
11. Two cans (pull cans) These cans are formed in different ways: single pull - a single pull operation is required. Tuna and ready-to-eat cans. Shallow tank (height less than diameter); Drawing and redrawing (DRD) - using tuna and instant cans, drawing and redrawing (DRD) or multiple drawing; Drawing and ironing (DI) This is a variant of DWI beer and beverage cans, which are eaten by pets and often have no exterior decoration.