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【Technical Class】The choice of bronzing process materials – Maypak

Cosmetic packaging mostly uses plastic as the raw material. In order to show the metal texture or upgrade the quality that the packaging itself does not have, it is often used to indirectly gain consumer recognition of texture and taste through bronzing, which is usually the edge bronzing or LOGO bronzing. It is common in the packaging of cosmetics, skin care and other products. With the development of bronzing, various customized patterns or special texture bronzing have also emerged.

  • Hot stamping process introduction

The basic process of bronzing is in the state of pressure, that is, when the anodized aluminum is pressed by the hot stamping plate and the substrate, the anodized aluminum is heated, and the hot-melt silicone resin layer and adhesive melt on it. At this time, the organic The viscosity of silicone resin becomes smaller, and the viscosity of special heat-sensitive adhesive increases after being heated and melted, so that the aluminum layer and the anodized aluminum base film are peeled off and transferred to the substrate at the same time. As the pressure is removed, the adhesive quickly cools and solidifies, and the aluminum layer is firmly attached to the substrate, completing a hot stamping process.

Hot stamping has two main functions: one is surface decoration, which can increase the added value of the product, and the combination of hot stamping and other processing methods such as concave-convex technology can show a strong decorative effect of the product; the second is to give the product higher anti-counterfeiting performance. Such as the use of holographic positioning hot stamping trademark logo and so on.

  • Features of hot stamping process

Hot stamping is a very widely used process in the current secondary process, and it also has its unique characteristics:

1. Low impact on the environment and low energy consumption (high conversion rate from electrical energy to thermal energy, less mechanical energy loss);

2. Low site requirements, flexible operation, and can be connected to molding, printing, and assembly for on-line production according to needs;

3. High degree of freedom in customization, and the appearance effect (such as special effect gold foil paper or transfer film) can be customized according to different customer needs;

4. Most of the actions of bronzing are mechanical actions, which can be relatively easy to achieve efficient automated integrated workstations.

  • Material selection for bronzing process

(1) Bronzing version

The hot stamping version includes: zinc hot stamping version, steel hot stamping version, copper etching hot stamping version, silicone hot stamping version, and resin hot stamping version.

The hot stamping version is required to be able to resist high temperature, high pressure and deformation. Because the hardness of zinc is much lower than other materials, this material is not chosen for products with high hardness and large output. The advantage of the zinc bronzing version is that it is easy to produce and cheap. Copper can resist high temperature and high pressure, but it is not easy to etch, especially in corners. Due to different materials, the heat exchange is also different. The most popular materials are silica gel and aluminum. The heat resistance temperature of silica gel is between 250°C and 350°C (the temperature between the hot stamping plate and the part is usually maintained at 80°C to 180°C) .

The choice of commonly used bronzing plates: silicone plate, copper plate, engraving plate.

Self-made silicone version: used for ironing product lines.

The recommended processing temperature range for the silicone plate is 250°C-300°C (silica gel over 350°C will easily harden and shorten the service life, usually set to about 250°C).

Corrosion silicone version: used for ironing of specific patterns, characters, lines, patterns, etc.

Engraved version: used for ironing of curved or irregular surface products.

Copperplate: used for ironing products that require obvious concavity and convexity. Copperplate processing temperature range: 100℃-200℃.

Iron-coated silicone wheel: used for ironing transfer foil and large-area lines.

Hollow silicone wheel: used for finishing the whole surface of the product. The processing temperature range of this silicone wheel is 200℃-300℃.

(2) Bronzing foil (electrochemical aluminum foil)

The hot stamping process uses the principle of heat and pressure transfer. For example, hot stamping aluminum transfers the aluminum layer in the anodized aluminum to the surface of the substrate to form a special metal effect. Anodized aluminum foil is usually composed of multiple layers of materials, and the base material is usually PE, followed by separation coating, color coating, metal coating (aluminum plating) and glue coating.

1. The appropriate hot stamping foil must be selected according to the different materials of the object being hot. When hot stamping, it is necessary to master the three-way coordination of temperature, pressure, and stamping speed (or time), and it will be different according to the difference of stamping materials and stamping area.

2. The speed and direction of the turning tool should be mastered when cutting the bronzing foil.

3. Anodized aluminum hot stamping foil should use suitable paper, ink (especially black ink), and composite glue. The hot stamping parts must be kept dry to avoid oxidation or damage to the hot stamping layer.

4. The general packaging is a roll of 64cm×120m, one box per 10 rolls; large rolls with a width of 64cm and a length of 120m or 360m or other special specifications (1.5m width, 1000m or 3000m length) can be customized.

5. Store it upright, pressure-proof, moisture-proof, heat-proof, sun-proof, and place in a cool, ventilated place.

Note: If the color of the gold foil is silver, there are generally only four layers of the gold foil (the anodized aluminum layer itself is silver). Most of the recommended gold foil thicknesses are 0.012mm and 0.016mm. If there are other three-dimensional effects, there will be 5-6 layers, and the extra layer is the effect layer.

Common colors of gold foil are: gold, silver, black, red, etc.

There is a certain difference between the transfer film and the electrochemical aluminum foil. The special transfer film sometimes requires special treatment or hot stamping construction conditions, which should be adjusted according to the actual situation.