Fine treatment of vacuum plating technology
In surface treatment technology, vacuum electroplating has become a new trend of environmental protection. It is safer, more energy-saving, reduce noise and reduce pollution emissions. Different from ordinary electroplating, vacuum electroplating is more environmentally friendly and can produce a good black gloss that ordinary electroplating cannot achieve. This paper shares the related knowledge of vacuum electroplating, and the content is provided for the selection of superior packaging material system for your reference:
Because the coating machine evaporates the target material under the vacuum condition, the process is called vacuum plating.
2, the principle
The process is that the steam source is heated by electricity in the way of low voltage and high current under vacuum conditions. The target material is dispersed to the surface of the workpiece under the condition of heating by electricity, and deposited on the surface of the workpiece in an amorphous or liquid form to cool the film formation process
The coating structure of vacuum coating is generally as follows: base material, primer, vacuum film layer and topcoat. The characteristics of the film layer are directly determined by the physicochemical properties of the target material. According to whether the film layer conducts electricity or not, it can be divided into conductive vacuum coating (VM) and non-conductive vacuum coating (NCVM).
VM: it is generally used in the surface treatment of cosmetics, NB, 3C, auto parts, decorative frames, and key RING ornaments. Its surface effect is comparable to that of water electroplating. The target materials are aluminum, copper, tin, gold, silver, etc.
NCVM: it has metal texture and transparency, but it is not conductive. It is generally used in the surface treatment of communication cases, 3C cases, decorative frames, key parts and RING ornaments with higher disturbance resistance. The surface effect is irreplaceable by water plating, and the target materials are indium and indium tin.
4. Distribution of membrane structure
Base material: ABS, PC, ABS+PC, PP, PPMA, POM and other resins can all be formed by vacuum electroplating. It is required that the base material is pure raw material with better electroplating level and no recycled material can be added.
Primer: UV primer is used to pretreat the surface of the substrate to provide an active interface for adhesion of the film.
Film layer: as a result of target evaporation, VM film layer can conduct electricity, while NCVM coating does not conduct electricity and has good anti-interference effect. The film thickness is less than 0.3um.
Topcoat: topcoat can match all kinds of colors with color paste based on the principle of three primary colors. Meanwhile, it can protect the vacuum film layer. With UV and PU surface decoration, the effect is more beautiful.
Mechanism of multi-color effect of topcoat: mixing and debugging of topcoat and color paste based on the principle of three primary colors, as shown in the figure below:
B. Equipment and environmental requirements
The quality of vacuum plating depends largely on the quality of equipment and environmental cleanliness (dust-free).
1. Equipment introduction
Large equipment has automatic assembly line body (including UV assembly line), vacuum coating machine, auxiliary equipment has product fixture, fixture, some factories also have robots.
2. Environmental requirements
1, paint room outside room: operating environment at least 10 universal level below
Painting the room
As shown in the figure below, the operating environment of the electrostatic dust removal section should be at least below 10,000 level.
Vacuum coating machine
As shown in the figure below, it is generally a door type device. Open the door to load and unload (half) products, and close the door to set parameters and conduct vacuum operation. The process environment must be operated under 100,000 level
We take a plastic part as an example: spray a layer of primer on the workpiece, and then do electroplating. Since the workpiece is a plastic part, air bubbles, organic gases remain in the injection molding, and moisture in the air is inhaled when placed. In addition, because the plastic surface is not smooth, direct plating of the surface of the workpiece is not smooth, low luster, metal feeling is poor, and there will be bubbles, blisters and other bad conditions. When sprayed with a primer, it creates a smooth, flat surface and eliminates the presence of bubbles in the plastic itself, allowing the plating to take place.
D.Common problems and causes
E. comparison with water plating characteristics
F. Application of cosmetic packaging materials
Vacuum coating is widely used in cosmetic packaging materials industry, such as external components of lipstick tube, external components of pump head, glass bottle, external components of bottle cap and so on.