What should be paid attention to when coating iron is baked?

What should be paid attention to when coating iron is baked?

In the metal packaging, the majority of the coating is applied to the tinplate (internal coating, outer coating), and then baked and then processed. Different types of products, very few metal drums are processed without direct processing. Because metal steel sheets, tin plating (chromium), etc., affect the food contained in the case of high temperature, which is harmful to the human body, it is required to have a high barrier layer for rust prevention, corrosion prevention, acid resistance and leakage prevention when the food is contained. The above requirements. Therefore, whether it is food, beverages, children's toys, pencil cases, etc. should be produced as required. This requires each printing iron can factory to master each link in coating, coating, baking, and manufacturing, in order to produce qualified products. The following only introduces several issues that should be noted in the baking of paint iron:

Baking is a process that must be possessed by coating iron.

The quality of the baking and the quality directly affect the quality of the post-processing and various quality problems caused by the processed food. Therefore, the coating iron plays an important role in baking. At present, in the equipment for coating iron baking, the basic heating system can be divided into four categories: coal heating, kerosene, natural gas heating and electric heating. The following requirements can be met regardless of the heating method.

Baking equipment performance and requirements

1. Baking equipment should have a fast heating rate, and the heat capacity can meet the requirements in a short time.

2. Have adequate air circulation and eliminate odor settings

3. Baking system has certain sealing and safety

4. Baking equipment must hold the product certificate of the relevant department

5. Baking equipment must have stable deformation resistance after use

6. The electrical parts used in the baking equipment must meet the national standard requirements.

7. Baking equipment should be reasonably used, easy to maintain and complete mechanical drawings

8. Transmission equipment must have reasonable timing and adjustable air cooling system

Many of the above conditions have been achieved in the old equipment of the past, and many manufacturers are further renovating. The performance of new equipment often exceeds the above requirements. Many equipments are basically equipped with fully automated devices, which provide convenience for operators. . However, often relying on some data does not necessarily meet the requirements of the product. It must also carry out various aspects of inspection and process adjustment during the baking process. These are all based on long-term accumulated experience. Once the adjustment of the baking process is neglected, This type of problem may occur with a variety of varieties, so the unreasonable baking or insufficient baking causes the corrosion of the food to occur. Therefore, the adjustment of the baking process can not be ignored.

Baking process adjustment

1. Process adjustment according to the material selected for the food to be loaded, namely iron plate coating

2. According to the use of the process description provided by the supplier, the baking temperature of the coating used and the amount of coating film applied during the production process to adjust the baking process

3. According to the performance of the coating, baking time to adjust to the best temperature and the best time

4. After passing the sample test, the first large sample test will be carried out in batch production, and the standard requirements will be met before mass production.

Problems caused by unreasonable baking

1. The coating iron has insufficient heat during baking. When the coating is covered, the coating film cannot adhere to the substrate, and the deformation is caused by cracking and breaking. This is because the coating film layer does not have enough heat to fully cure, and the crosslinking reaction does not reach the coating film flexibility of the coating itself, so that the surface tension of the coating film reaches the optimum performance. Micro-cracks or broken parts may corrode for a long time after being filled with food.

2. The quality problem caused by the temperature being too high during baking and the time is too long. When the temperature is too high, the surface of the coating film will become brittle, the surface tension will be lost, the density of the coating film and the micropore shrinkage will be destroyed, and the surface will be destroyed and the microcracks will be retracted. Like air bubbles, it will corrode quickly after being filled with food, causing the product to fail.

3. The baking temperature adjustment room is unreasonable, the coating film adhesion strength is poor, and the micropores are not resistant to impact. Microbubbles appear after baking, which is caused by unreasonable temperature adjustment of the baking. The baking temperature should be from low temperature to high temperature and then low temperature. The low temperature zone is the pre-coating preheating zone of the drying room. It mainly combines the temperature of the iron plate with the coating layer to allow the low-boiling solvent to start to volatilize and enter the curing state. . Therefore, quarterly factors must also be taken into consideration when adjusting the heat, temperature, and time in the low temperature zone. If entering the oven immediately enters the high temperature zone or the temperature is too high, the surface of the coating film forms a pseudo-dry phenomenon. At low temperature, the high-boiling solvent escapes from the coating film little by little, forming small bubbles, reducing the coating film on the coating film. After the surface tension, the processed barrel can be peeled and peeled off after being filled with food.

In short, the coating iron must be strictly adhered to the baking process of various varieties when it is baked. The new standard QB/T2763-2006, which was implemented on December 1, 2006, clearly stipulates that relevant companies can deeply understand the content of the new standard.