If you understand the history of Tinplate development,
If you have mastered the application characteristics of tinplate,
If you know the bottleneck of the printing and canning industry,
The emergence of laminated iron is an inevitable result of the development of science and technology, and it has brought hope and confidence to the printing and canning industry.
One, tinplate
Since the introduction of tinplate, it has been developing in the direction of thinning. One is to use less tin, or even no tin (chrome-plated iron). One is to reduce the thickness of the base plate of tinplate. The purpose is to adapt to changes in canning products and reduce the cost of can making.
1, tin layer: from the 50's hot dip tinplate development to the current electroplated tinplate, now China can not see the use of hot dip tin cans in the canning. To familiarize yourself with the history of tinplate, the list is as follows:
Hot dip tinplate tin plating amount:
Code number of tin plating (two sides) g/m2 China's application example
H12/12 24
H14/14 28
H15/15 30 1.5 lb tin fruit and vegetable, meat
H17/17 33.6
Tin plating amount of electroplated tinplate:
Code number of tin plating (per side) g/m2 China's application example
10# 1.1/1.1 No. 10 except that the tin content of No. 100 is used for canning of mushrooms, fruits, etc., generally iron of the tin content below No. 50 is used for iron-iron coating processing.
25# 2.8/2.8 25
50# 5.6/5.6 50
75# 8.4/8.4 75
100# 11.2/11.2 100
2. Substrate thinning: This is a common wish of all people. At present, 0.15m/m tinplate has been used to make lids in China. Some cold-rolled sheet companies have announced that they can produce 0.12m/m cold-rolled sheet for the capping industry. Therefore, the secondary cold-rolled tinplate with thinned substrate and enhanced hardness is the development direction of can making (cover) industry.
The list of tempering grades for tinplate in the world is as follows:
Secondary cold rolled tinplate:
Traditional Symbol Current Symbol HR30T Value Tensile Strength (MPA) Use
DR8 DR550 73 550+70 Round Can Body, Bottom, Cover
DR9 DR620 76 620+70 Round Can Body, Bottom, Cover
DR9M DR660 77 660+70 Bottom and lid for beer and carbonated beverage cans
One cold rolled tinplate:
T1 T50 52 330 extremely harsh deep drawing
T2 T52 52 350 Deep Draw
T2.5 T55 55 General use
T3 T57 57 370 General use, can body not scratch
T4 T61 61 415 For general use, high rigidity, rigid bottom, lid, shallow flush tank, etc.
T5 T65 65 450 Warp resistant, requiring rigid base, lid, can body
T6 T70 70 530 Very rigid, bottom and lid for beer, carbonated beverage cans
For the same tank type, the cold rolling tinplate can be used to make thin thicknesses to increase the utilization of tinplate.
3. Chromium-plated iron: This is the Wuxi steel sheet. Since it was promoted to China in the 1980s, it has been in an awkward state until it was widely used after 2000. Even this year, there will be a situation where the price of chrome-plated iron is more expensive than that of tin-plated iron. The reason is that the processability of chrome-plated iron is significantly better than that of tin-plated iron. With the widespread use of coating iron, especially in the cap, chrome-plated iron has received more attention from people. The characteristics of chrome-plated iron are:
(1) The canning process and corrosion resistance of the substrate are the same as those of the tinplate;
(2) In the coating process, the tin melting problem like tinplate does not have to be considered, and a higher baking temperature can be used to increase the printing and coating production efficiency;
(3) Adhesion to coating is better than tinplate;
(4) The surface is a very thin layer of metal chromium and hydrated chromium oxide. The thickness is only about 1% of the tin tin layer. Therefore, it is easy to rust. Therefore, there is no practical value of chrome plating without coating processing.
(5) Because it is a thin sheet of Wuxi, it has saved tin resources and is in line with the development direction of tinplate.
Tinplate and chrome iron performance comparison:
Performance Tinplate Chrome Iron
Exterior
No printed AC
There are printed AB
Iron (paint) CA
Film dense CA
Pull-out CA
Processability (stretching) CD
Impact resistance BB
Weight 7.8 7.8
Heat resistance 232 °C tin melting stable
Sulfur resistance DA
Resistant to acid and high tin content do not have to be printed and can be used after printing B
(A-better B-good C-middle D-poor)
Second, the coating iron: refers to the inner coating of the printed tinplate (chrome plated iron), applicable to all areas of metal container Packaging, to provide additional features tinplate - decorative, corrosion resistance, etc., which is more obvious in the canning industry, In general, the inner coating is epoxy resin-based coating, and the outer coating is divided into base coating, white coating, and glazing coating, and is mainly composed of acrylic acid and polyester resin. Iron printing inks have the properties of heat-curing and UV-curing (UV), but printing ink must be matched with the coating to ensure the ink's color, adhesion and other properties. As the coatings currently used are still based on solvent-based coatings, there are still environmental issues that need to be resolved. In addition, for the tomato sauce cans, deep-drawn two-piece cans, etc., our coating iron is still not stable enough, so it is necessary to recommend covering paint.
1. Tomato Sauce Jar Coating: The traditional 214×3 coating iron is suitable for canned tomato sauce, tomato juice and other cans below 22°. The golden yellow transparent coating gives pleasure, but for 28° tomato sauce cans, the use of masking Coatings are the trend of the times. Because the masking coating solves the conflict between the cohesion and the surface adhesion of the coating film, it also solves the contradiction between the corrosion resistance and the adhesion of the coating.
Covering paint meaning:
Any coating film can not be perfectly compact, and the corrosion factor will cause electrochemical corrosion through the coating film and the tin layer on the tinplate during the canning of the tomato sauce jar, so that the tin ions will peel off. If the adhesion of the coating film is poor, the black tin layer and the peeling of the coating film will be observed on the inner wall of the can. The use of a covering paint is like a layer of fig leaf. The above-mentioned corrosion change is invisible to the naked eye. If the hiding power of the covering film is small and the adhesion is good, the above-mentioned corrosion change is small, and the storage time of the tomato sauce can is prolonged. However, it is important to remember that this corrosion process is always in progress and the final judgement of the deterioration of the ketchup cans is to see if the cans are "hydrogen-fat". In April this year, an imported 70g ketchup can was observed by Origin as "hydrogen fat". However, after the cans were opened, the khaki paint on the inner wall was intact and there was no corrosion spot, indicating that the paint played a role as a fig leaf.
Cover coating and 214 × 3 coating iron also play a role in reducing costs, that is, a coating, a coating thickness of 11g/m2, adhesion level 1-2, which is 214 × 3 coating iron can not be compared.
2. Two-piece can coatings: Light flush cans are still available with 214-type epoxy coatings to solve the problems of impact resistance and corrosion resistance, but for high-sulfur fish and meat cans, due to strong corrosion, the inner wall of the film stretching position Easily corroded, the use of masking paint can enhance the denseness of the coating and prolong the corrosion time. Such as lunch cans use zinc oxide coating cans, fish cans use aluminum powder coatings, these are covered coatings.
Third, laminating iron: through the fusion or bonding method, the composite film of plastic film on the cold rolled steel sheet called "laminated steel" (Laminated Steel), the relative coating of iron, also can be called "plastic iron" . In fact, this kind of composite material has been widely used in home appliances and decorative materials over 10 years ago. However, it has been applied in the printing and canning industry in recent years. With regard to the reports on iron laminating, foreign documents are mostly Japanese, and China’s “Metal Packaging” publications have also been reported one after another. In the third issue of the publication I published a detailed introduction to the birth of Chinese iron film. However, it is necessary to clarified the following for the upgrading and replacement of coating iron for laminated iron:
1. Performance: The impact resistance and corrosion resistance of laminating iron is unmatched by coating iron. Because it is a plastic film composite board. In other words, the coating iron has the conflict of corrosion resistance and adhesion, and it is easily solved for the film iron. This is ideal for the packaging of tomato sauce cans and two-piece cans.
2. Material cost: As the laminating iron is a kind of metal material with both the plastic film and the metal sheet. Therefore, under normal circumstances, it is not necessary to use tinplate as a substrate for the production of laminated iron. This is a clear indication of the cost advantage of using cold-rolled sheet laminates in the current situation where tinplate prices have skyrocketed.
3. Environmental protection and energy consumption: The production of laminating iron is free from exhaustion of solvent exhaust gas, and the film formation temperature is only about 70°C. Therefore, the production cost is also much lower than that of coating iron.
Despite the characteristics of laminated iron, there is no future. However, the application of printed iron cans has just started. The following problems must be carefully studied to explore the healthy development of iron film.
1. Metal Containers include food cans, beverage cans, chemical cans, miscellaneous cans, lids, and barrels. The requirements for laminating iron are not the same. Therefore, plastic films, adhesives, and colds with different properties are selected. Rolling sheet is a meticulous long-term tracking work.
2. The color film blanking and laminating technology is a must for China. If cold-rolled sheet is used as a laminating iron substrate, then how to keep the cold-rolled sheet from corrosion is a proprietary technology. Now, it has been settled on spray cans, but it will take time on food and beverage cans.
3, the production of laminating iron is coiled film, the production line is about 80 meters, and the investment in fixed equipment is relatively large. Therefore, in order to comprehensively promote the application of coated iron in printed iron cans, the research and development of the laminated film production line must not be ignored. In the next year, Ruixing will invest in the development of this project.
In short, the emergence of laminated iron is encouraging, but it is also a long way to go, and work together!
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