Iron coating is a type of coating applied to the surface of a tinplate print that has been completely colored or applied directly to the metal. I would like to analyze some of the quality problems in the process of printing oil coating in the current work and I would like to share with you.
First, common defects:
In the actual production work, there are several common defects that are often difficult to overcome with Indian iron varnish:
1: Cracking and shedding often occur during mechanical processing or high-temperature cooking and high-temperature baking, especially if our tinplate packaging products require deep-drawing processing and multiple mechanical processing, high-temperature sterilization and cooking. This phenomenon is prone to occur. This phenomenon not only affects the appearance of the product, but also makes the optical oil layer lose its protective effect.
2: The thickness of the optical oil layer is not uniform, the accumulation of the optical oil layer, defects such as pinholes and drags, etc. These defects not only affect the appearance of the product, but also reduce the product value. In severe cases, the optical oil layer will lose its role.
II: Influencing factors:
1. Optical oil layer adhesion:
The adhesion of the optical oil layer refers to the bonding strength of the optical oil layer to the surface of the tinplate. When the adhesion is increased to a certain extent, the elasto-plastic deformation of the optical oil layer is enhanced, and at the same time, it adheres firmly to the surface of the tinplate and deforms with the deformation of the tinplate. The factors affecting the adhesion mainly include the surface treatment conditions of tinplate, the chemical properties between the surface of varnish and tinplate, and the degree of curing of the varnish layer.
2. Hard oil layer hardness:
The hardness of the varnish layer refers to the binding strength of the varnish layer after curing, and is one of the important performance indicators of the mechanical strength of the varnish layer. Increased hardness increases the ability to withstand external forces. The hardness of the varnish layer is related to the properties of the varnish itself and the degree of curing.
When the adhesion and hardness of the lacquer layer increase, the impact resistance of the lacquer layer increases, so that the optical oil layer can be effectively prevented from cracking and falling off.
Second, preventive measures:
1. Tinplate surface oil film:
Before applying varnish, make sure that the oil film on the surface to be coated is removed. To find out the type and volatility of the oil film, determine the dry-drying temperature and speed based on the thickness of the oil film.
2. Coating thickness:
First, according to the product requirements to determine the basic thickness of the coating, and then select the viscosity of the light oil according to the amount of coating touch. The performance of the coating system is a major factor affecting the uniformity of the coating.
3. Curing temperature:
Curing temperature is one of the main factors to ensure the quality of the optical oil layer. In the production practice, the temperature curve of the oven under the curing temperature should be periodically tested, and there can be no large fluctuations. When the furnace temperature fluctuates greatly, check that the production speed is too fast.
4. Curing time:
Curing time is also one of the main factors affecting the curing state. Within a certain range, fixed time and curing temperature have a certain complementary relationship, tinplate curing time is too long, varnish may have a yellowing phenomenon.
5. other:
Should be based on the air changes in different seasons to develop the corresponding production process, the specific analysis of specific issues, can not be across the board, in the actual production should take every step seriously, so as to avoid unnecessary losses.
Ao Ruijin Deng Tixiang
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