Causes of oxidized spots on hot stamping paper

The oxidation of the bronzing paper after bronzing is mainly affected by the bronzing substrate. Generally, the substrate is too acid-base, and the bronzing paper is metal-plated aluminum layer. The reaction between aluminum and acid-base is relatively fast, so it is good after bronzing , After a period of time, it will discolor and oxidize to cause spots, and the higher the temperature, the more serious it will be. Let's take a look at the oxidation problem of bronzing paper after hot stamping.

From the structure distinction, bronzing paper can be divided into:

1. Basic layer

The main function is to support the various coatings on it to facilitate continuous hot stamping during processing. The base layer of the hot stamping paper is made of 12um or 16um thick PET film, which has the characteristics of tensile resistance and high temperature resistance. During the hot stamping process Will not be deformed or broken due to the heating of hot stamping. The base layer determines the thickness.

2. Peeling layer

The release layer is generally formed by coating a silicone resin or the like. The main function is after hot stamping (heating and pressing), the color material, aluminum, and adhesive layer can be quickly separated from the polyester film and transferred and bonded to the surface of the hot stamped object. The peeling layer must have a good shedding performance, otherwise it will make the hot stamping graphics and text blurred, exposed, white, etc., which will affect the quality of the hot stamping product. The peeling layer determines the size of the hot stamping area.

3. Color layer

The main components of the color layer are synthetic resins and dyes with suitable film-forming properties, heat resistance, and transparency. Commonly used resins include polyurethane, nitrocellulose, melamine formaldehyde resin, and modified rosin resin. During production, the resin and dye are dissolved in the original color paste of the organic solvent, and then coated and dried. There are two main functions of the color layer, one is to display the color; the other is to protect the hot stamping of the aluminum-plated layer on the cover or the surface of other objects from being oxidized.

The color of anodized aluminum foil is golden, orange, gray, red, blue, green, etc. The color of the color layer is given luster through the aluminized layer, and the color changes to a certain extent. For example, the yellow is golden or gray after aluminizing. It becomes silver after plating. The coating requirements for the color layer are fine and without any small particles, so as to avoid trachoma, and the coating is uniform and consistent. For parts that are prone to chromatic aberration, the way to check the chromatic aberration is to stick it with transparent adhesive paper and look at the back. At this point, the bronzing paper is very rich in color, full of color and no color difference.

4. Electroplating layer

The colored film is placed in the vacuum chamber of the vacuum continuous aluminum plating machine, and the aluminum wire is melted and continuously evaporated to the color layer of the film through resistance heating under a certain vacuum degree to form the electroplating layer. The main function of the electroplating layer is to reflect light, change the color of the color layer, and make it appear metallic.

5. Glue layer

The glue layer is generally a fusible thermoplastic resin, such as methyl methacrylate (ethyl ester, butyl ester) and acrylic copolymer. Depending on the material to be stamped, other resins such as Cuban gum, shellac, rosin, etc. can also be used . The resin is dissolved in an organic solvent or formulated into an aqueous emulsion, coated on the aluminum layer, and dried to form an adhesive layer. The main function of the glue layer is to bond the hot stamping material to the object to be ironed.