The bronzing process is commonly known as anodized aluminum hot stamping, which has the characteristics of bright color, noble and gorgeous, and is currently widely used in various high-end trademarks, manuals, greeting cards and cigarette labels. At the same time, water-based glazing has the characteristics of colorless, odorless, strong transparency and non-toxic, no organic volatiles, low cost, good gloss, folding resistance, wear resistance and chemical resistance, etc. It is the preferred finishing process for high-end prints.
As users pursue the effects of printed materials, more and more printed materials are applied with the process of first glazing and then bronzing, and then there are some process problems. Among them, the problem of bronzing after water and oil is a common problem. The so-called bronzing after hot water is not hot, is to perform bronzing processing on the varnish film layer after the printed product has completed the water-based glazing process, and the bronzing graphics and text appear flowery, exposed or not transferred at all.
Before solving this problem, let's first understand the structure of anodized aluminum used for bronzing. Anodized aluminum is generally composed of five different materials: the first layer is a base film layer, mostly a polyester film, which determines the strength of the anodized aluminum; the second layer is a separation layer, the main component is a hot-melt silicone resin, After melting, it will melt and fall off automatically, which determines the separation performance of anodized aluminum; the third layer is a colored layer, which is composed of heat-resistant synthetic resin and dye, and determines the color of anodized aluminum; the fourth layer is an aluminized layer, which is gaseous aluminum under vacuum It is formed by uniformly adhering to the surface of the colored layer, which plays the role of increasing the color; the fifth layer is a hot-melt adhesive film layer, which is mainly composed of hot-melt adhesive. Different uses and models are determined by this layer.
When bronzing after water and oil processing (as shown in Figure 1), the direct factor of the bronzing results is the adhesion of the hot-melt adhesive on the surface of the substrate, and the factors that affect the adhesion of the adhesive include hot stamping temperature, Stamping pressure, stamping time, the properties of anodized aluminum compound and the surface of the object to be ironed, etc.
Figure 1 Schematic diagram of bronzing after varnish
Note: 1 base film layer; 2 separation layer; 3 colored layer; 4 aluminized layer; 5 hot melt adhesive film layer; 6 varnish film layer; 7 printed products.
When the phenomenon of hot stamping fails after water and oil, you can first increase the hot stamping temperature and increase the hot stamping pressure to solve; if not, you can reduce the speed and use soft padding to increase the hot stamping time; if the above measures If it cannot be solved, it is necessary to consider whether the properties of the hot melt adhesive film compound and the surface of the varnish film layer match. Generally, the anodized aluminum with high viscosity can be replaced first; if it is not hot enough, you should consider replacing the water-based varnish with good hot stamping suitability. Obviously, if the choice of water-based varnish makes the bronzing impossible, it will make a large number of printed products scrapped and economic losses will be serious. Therefore, it is very important to choose an aqueous varnish with good hot stamping suitability before glazing.
Water-based printing varnish is mainly composed of resin, solvent and additives. Water-based resin is the main film-forming substance of glazing oil, usually synthetic resin, which affects various physical properties and glazing quality of the film layer. The main role of the solvent is to disperse or dissolve synthetic resin and various additives. The solvent of water-based varnish is mainly water. The volatility of water is almost zero. Its leveling performance is very good. However, water as a solvent for water-based glazes also has shortcomings, such as slow drying speed, easy to cause process failures such as product size instability. The additive is to improve the physical and chemical properties and processing characteristics of the water-based resin. As long as you understand the characteristics of hot stamping anodized aluminum, choose a water-based glazing oil with good hot stamping properties, and adopt a reasonable processing technology, you can avoid the failure of hot stamping after the printed product is over water and oil.
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