Technical information related to tinplate packaging materials

Since the advent of tinplate, it has been developing in the direction of thinning. One is to use less tin, or even not to use tin (chrome-plated iron), and the other is to reduce the thickness of the tinplate substrate. The purpose is to adapt to changes in canned products and reduce the cost of canning.

 

Tin layer

From the development of hot-dip tinplate in the 1950s to the current electroplated tinplate, the use of hot-dip tinplate in can making has not been seen in my country. To get familiar with tinplate

Historical overview of , the list is as follows:

Tin plating amount of hot dip tinplate:

Code Tin plating amount (both sides) g/m2 Chinese name Application example

H12/12 24

H14/14 28

H15/15 30 1.5 lb tin quantity Fruits, vegetables, meat

H17/17 33.6

Tin plating amount of electroplated tinplate:

Code Tin plating amount (each side) g/m2 Chinese name Application example

10# 1.1/1.1 No. 10 In addition to the amount of tin of 100, which is used for canned mushrooms, fruits, etc., iron with the amount of tin below 50 is generally used for iron printing 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

 

Substrate thinning

This is a well-known wish. Currently, 0.15m/m tinplate has been used in our country to make covers. Some cold-rolled sheet companies have announced that they can produce 0.12mm cold-rolled sheets for the lidding industry. Therefore, the thinning of the substrate and the secondary cold-rolled tinplate with enhanced hardness are the development direction of the can (cover) industry.

The list of quenching and tempering grades of 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, Lid

DR9 DR620 76 620+70 Round Can Body, Bottom, Lid

DR9M DR660 77 660+70 Bottom and lid of beer and carbonated beverage cans

A cold rolled tinplate:

T1 T50 52 330 Extremely demanding deep drawing

T2 T52 52 350 Deep drawing

T2.5 T55 55 General use

T3 T57 57 370 For general use, the can body is not scratched

T4 T61 61 415 General use, high rigidity, need rigid bottom, cover, shallow flush tank, etc.

T5 T65 65 450 Warpage resistance, requires rigid bottom, lid, can body

T6 T70 70 530 Very rigid, the bottom and lid of beer and carbonated beverage cans

For the same tank type, the second cold-rolled tinplate can be used to replace the thickness with thinness, so as to improve the utilization rate of tinplate.

 

chromed iron

That is, Wuxi thin steel plate has been in a state of lingering since it was promoted to my country in the 1980s. It was not widely used until after 2000. Even in this year, the price of chrome-plated iron is more expensive than that of tin-plated iron. The processing performance of the printed iron coating is obviously better than that of tinned iron. With the widespread use of painted iron, especially in bottle caps, chrome-plated iron has received more attention. The characteristics of chrome-plated iron are:

(1) The can-making process and corrosion resistance of the substrate are the same as those of the tinplate substrate;

(2) In coating processing, it is not necessary to consider the tin melting problem like tinplate, and a higher baking temperature can be used to improve the production efficiency of printing and coating;

(3) The adhesion to the coating film is better than that of tinplate;

(4) The surface is a very thin layer of metallic chromium and hydrated chromium oxide, and the thickness is only about 1% of the tinplate tin layer. Therefore, it is very easy to rust. Therefore, without coating processing, there is no practical value of chrome-plated iron.

(5) Because it is a Wuxi sheet, it saves tin resources, which is in line with the development direction of tinplate.

 

Performance comparison

Properties Tinplate Chrome Plated Iron

Exterior

No printing A C

Printed A B

tinplate
Tinplate (20 photos)

Printing iron (paint) property C A

Film Density C A

Punchability C A

Processability (stretch) C D

Impact resistance B B

Specific gravity 7.8 7.8

Heat resistance 232℃ tin melting stable

Sulfur resistance D A

Acid resistance High tin content can be used without printing After printing B

(A-Excellent B-Good C-Medium D-Poor)
Hardness test of tinplate

In the past, the hardness test of tinplate mostly used a desktop surface Rockwell hardness tester and an ordinary steel flat anvil to test the hardness of HR30T.

Over the years, since the national standard GB/T2520-2000 on tinplate has adopted the internationally accepted HR30Tm hardness representation method, diamond anvils have been used in China to test the HR30Tm hardness value of tinplate.

However, a diamond anvil is required to test the hardness of HR30Tm, and such accessories are rarely available for domestic Rockwell hardness testers. Because suitable diamond anvils are difficult to obtain, benchtop surface hardness testers are more expensive. Therefore, the application of HR30Tm hardness representation method in the domestic tinplate industry is not common. Especially in the use of tinplate manufacturers, although people always realize that the hardness of tinplate is very important, it is related to the quality of processed products, production efficiency and enterprise benefits. However, most companies have not re-inspected the hardness of purchased tinplate materials.