1.What is tinplate
Tinplate is one of the alloys we often talk about now. The chemical properties of alloys are very good and can combine the advantages of two or more metals. Tin is chemically stable and does not corrode easily. Iron is not chemically stable and is easily oxidized, but the hardness of iron is great and the formability is good. Tin is often plated on tin to prevent rust. This kind of tin with tin "clothes" is known as "tinplate". One ton of tin can cover more than 7,000 square meters of iron sheet, so tinplate is very common and very cheap. The biggest "customer" of Ma Kou iron is the canning industry. If you pay attention to protection, tinplate can be used for more than ten years and maintain rust. However, once you accidentally touch the "clothes" of the tin, the iron sheet will soon be rust (electrochemical corrosion), and soon, the whole sheet of tinplate will be covered with red-brown iron rust spots. Therefore, when using tinplate, care should be taken not to damage the tin layer and not to get it damp and heated.
2. Characteristics and advantages for Tinplate
1) Opacity
In addition to triggering food spoilage reactions, light also causes changes in proteins and amino acids. Exposure to light makes it easier for vitamin C to interact with other food ingredients, resulting in significant losses. According to research and analysis, the loss of vitamin C in transparent glass bottles of milk is 14 times higher than that in dark bottles of milk, light will also cause milk to produce oxidative odor, as well as nuclide, methylthiamine and other cracking and loss of nutritional value, tinplate can opaque light makes the preservation rate of vitamin C the highest.
2) Good sealing
The barrier of packaging containers to air and other volatile gases is very important for the preservation of nutrients and sensory quality. The comparison of various juice packaging containers showed that the oxygen permeability of the container directly affected the Browning and vitamin C preservation of the juice. The preservation of vitamin C is better in metal cans, glass bottles, aluminum foil glue layers and cartons with low oxygen transmission rate, of which iron cans are the best.
3) Reduction of tin
The tin in the inner wall of the tin plate will interact with the oxygen remaining in the container during filling, reducing the chance of the food ingredients being oxidized. The reducing effect of tin has a good preservation effect on the flavor and color of light colored fruits and juices, so the juice cans filled with unpainted iron cans have better nutritional preservation than those filled with other packaging materials, and the Browning change is slight, the acceptance of flavor quality is better, and the storage period is extended.
4) Provide a source of available iron
Tinplate canned food, except for a few light colored fruit and juice cans, mostly use empty cans painted inside to improve the corrosion resistance of the container; Due to the electrochemical action of the metal, there will be a small amount of iron dissolution in storage, in the form of bivalent iron in sealed canned food, it is easy to be absorbed by the human body, the content of about 1 to 10ppm. In terms of fruit and vegetable products, the raw material itself does not contain much iron, and the iron can products are calculated with 350ml beverage cans per can, the iron content is 5ppm, and each can can provide 1.75mg of iron, about one-tenth of the human body's daily intake of 18mg. If the above fruit and vegetable juice beverage cans are rich in vitamin C, iron is more easily absorbed, so canned food and beverage is a good source of iron, and the significance of nutrition for canned food is more profound.
3. Classification of tinplate
1) Single cold-rolled tinplate
Grade: T1, T2, T3, T4, T5, T6 substrate is annealed by hot rolling after a cold rolling, usually the thickness of 0.17-0.5mm, English is Single Reduce, referred to as SR.
2) Double cold rolled tinplate
Brand: DR-8, DR-9, DR-9M, DR-10 substrate by hot rolling after a cold rolling annealing, and then a cold rolling, the second cold rolling is named, usually the thickness of 0.12-0.36mm, English is Double Reduce, referred to as DR. The double cold rolling has thinner thickness and higher strength, can reduce the cost of making cans, and the overall proportion of use is constantly increasing. And the production process is more sophisticated and complex, the supply capacity is relatively small, and it belongs to the varieties that are better sold in overseas markets.
3) Equal thickness tinplate
Common tin plating amount: 2.8/2.8, 5.6/5.6, 8.4/8.4, 11.2/11.2 tinplate with less tin plating amount is generally used for containers with low corrosion resistance and containers used for painting; Tinplate with a large amount of tin plating is generally used for cans with high corrosion resistance requirements, and containers that are used directly without painting.
4) Differential thickness tinplate
Common tin plating amount: 5.6/2.8, 8.4/2.8, 8.4/5.6, 11.2/2.8, 11.2/5.6, 11.2/8.4, 15.1/5.6 tinplate with less tin plating amount is generally used for containers with low corrosion resistance requirements and containers used for painting; Tinplate with a large amount of tin plating is generally used for cans with high corrosion resistance requirements, and containers that are used directly without painting.
5) MR Food grade tinplate (Tinplate)
The vast majority of food packaging with tinplate steel base. The residual trace elements are less, and it has excellent corrosion resistance.
4. ApplicationT of Tinplate
The application of tinplate is very wide, from as food and beverage packaging materials to grease cans, chemical cans and other miscellaneous cans, the advantages and characteristics of tinplate provide content in the physical and chemical properties of good protection.
1) Canned food
Tinplate can ensure food hygiene, minimize the possibility of corruption, effectively prevent health risks, and also meet the needs of modern people in the diet of convenience and speed.
2) Beverage cans
Tinplate cans can be used to fill juice, coffee, tea and sports drinks, can also be filled with cola, soda, beer and other drinks. The high workability of the tinplate can make its tank type change more, whether high, short, large, small, or square, or round, can meet the diversified needs of today's beverage packaging and consumer preferences.
3) Grease cans
Light will trigger and accelerate the oxidation of oil, reduce nutritional value, may also produce harmful substances, more serious is the destruction of oil vitamins, especially vitamin D and vitamin A.
The oxygen in the air promotes the oxidation of food oil, reduces the biomass of protein, destroys vitamins, and the tinplate is opaque and the insulation effect of sealed air, which is the best choice for packaging fat food.
4) Chemical tank
Tinplate material is strong, good protection, no deformation, shock resistance, fire resistance, is the best packaging material for chemicals.
5) Spray and other miscellaneous cans
Can withstand high temperature and high pressure tinplate cans, especially suitable for high pressure filling spray cans. The changeable shape of the cans and the exquisite printing of the cracker barrel, the pencil case and the milk powder can are tinplate products.
