I. Introduction of ABS
Chinese name: ABS plastic English name: Acrylonitrile Butadiene Styrene plastic Chemical name: acrylonitrile-butadiene-styrene Molecular formula: (C8H8 · C4H6 · C3H3N) n (but it is often a graft polymer containing butadiene and Mixture of acrylonitrile-styrene copolymer) Structural formula: Melting point: 217 ~ 237 ° C (thermal decomposition temperature is above 250 ° C) Plastic ABS resin is currently the largest and most widely used polymer. ABS is acrylonitrile and butadiene. It is a terpolymer of styrene and styrene. It organically unifies various properties of acrylonitrile (A) butadiene (B) styrene (S), and has excellent mechanical properties of toughness, hardness, and rigidity. Acrylonitrile gives ABS resin chemical stability, oil resistance, certain rigidity and hardness; butadiene improves its toughness, impact resistance and cold resistance; styrene makes it have good dielectric properties and presents good Processability.
Application of ABS
3D printing
ABS plastic is one of the main materials for 3D printing. The reason why it can become a 3D printing consumable is its characteristics. ABS plastic has heat resistance, impact resistance, low temperature resistance, chemical resistance and electrical properties. , Product size stability and so on. At present, ABS plastic is the most stable material in 3D printing materials.
2. Various electrical appliances
Due to the high gloss and easy formability of ABS, ABS is also widely used as a raw material in home fax machines, stereos, and VCDs. Many ABS parts are also used in vacuum cleaners, and ABS parts are also used in kitchen appliances. Office equipment and machines need to have a beautiful appearance and good feel, such as telephone casings, memory casings, and computers, fax machines, and copiers that use ABS parts.
3.Requirements for plastic ABS in automotive interiors
Important goals pursued by automotive interiors include aesthetics, low odor, mechanical properties, heat resistance, and weather resistance. ABS automotive materials can meet the requirements for the use of various interior components. The materials have the following conditions:
1) Good liquidity
2) Excellent impact resistance
3) Easy processing
4) Easy to color and spray
5) Low odor
6) Good corrosion resistance
7) Matt effect
4. Cosmetic packaging materials
It has good rigidity, hardness and processing fluidity in cosmetic packaging materials, and has high toughness characteristics. It has a variety of applications, such as plastic bottle caps, plastic bottle shoulder covers, lipstick tube shells, etc. are made of ABS.
Third, plastic plating
1 Overview
Compared with metal parts, plastic electroplated products can not only achieve a good metal texture, but also reduce the weight of the product. While effectively improving the appearance and decoration of the plastic, it also improves its electrical, thermal and corrosion resistance. Performance, improving its surface mechanical strength. However, the selection of plastic materials for electroplating must comprehensively consider factors such as material processing performance, ease of plating, and dimensional accuracy. And because of its structural advantages, ABS plastic not only has excellent comprehensive properties, is easy to be processed and formed, but also has a high surface adhesion due to the material’s easy erosion, so it is currently widely used in electroplating.
2.Principle
The purpose of plastic plating is to coat the plastic surface with metal, which not only increases the aesthetic appearance, but also compensates for the shortcomings of plastic, imparts the properties of metal, and gives full play to the characteristics of plastic and metal in one. However, the electroplating process is a closed circuit, and all parts must be conductive. As everyone knows, plastic is non-conductive. To solve this problem, we need to use electroless plating before electroplating. The purpose of electroless plating is to create a layer on the surface of plastic products A conductive metal film creates conditions for plating metal layers on plastic products.
3. System composition
1) Electroplating equipment
The biggest functional advantage of electroplating is that on the surface of metal and non-metal parts, a new and extremely shiny metal layer can be formed, which directly improves the visual grade of the original part. The cost is much lower compared to forming parts directly from metal. Specific areas of the same component surface can be plated. Special waxes and coatings can be used to coat areas that do not require plating. Chromium plating is widely used in the surface treatment of vehicles and furniture industries.
2) In terms of plastics, ABS is the most commonly used, because ABS can withstand a high temperature of 60 ° C (140 ° F), and its bonding strength between electroplated and non-plated layers is high. Most metals can be electroplated, but different metals With different levels of purity and plating efficiency. The most common are: tin, chromium, nickel, silver, gold, and rhodium (rhodium: a type of platinum that is extremely expensive and can maintain high brightness for a long time. It can resist most chemicals and acids. It is most commonly used to gloss the surface of products Products with extremely high requirements, such as trophies and medals), nickel metal cannot be used for electroplating products that contact the skin, because nickel is irritating and toxic to the skin. 3) Coating description According to the coating, it can be divided into chrome, copper, and Cadmium, tin plating, galvanizing, etc.
4. Process flow
1) clean up
Stress Relief: Because the plastic parts have stress after injection, in order to minimize the deformation after plating, soak the plastic parts with glacial acetic acid to remove the stress.
Degreasing: In order to ensure uniform contact with the solution during roughening, it is necessary to remove the greasiness on the plastic parts by using a low-temperature alkaline agent.
Roughening: Generally, the surface of plastic parts is roughened by using high chromic acid solution to ensure the contact area with the solution.
Neutralization, reduction, and acid soaking: before removing strong acids, strong oxides, and impurities on the plastic surface for activation, increase the affinity of the plastic surface.
2) Chemical plating
Sensitization: Adsorb reductive divalent tin ions on the surface of the plastic part to prepare for activation.
Activation: For the needs of metal plating, a layer of catalytically active precious metal, such as Ag, is adsorbed on the surface of the plastic part.
Reduction or degumming: After the activation cleaning, reduction treatment is required to improve the surface activity and accelerate the deposition. At the same time, the activation liquid remaining on the surface is removed to prevent decomposition caused by being brought into the chemical plating solution.
Electroless plating: Before the electroplating of plastics, a metal plating layer with good conductivity must be formed. The plating layer is uniform and continuous, ensuring that the current can form a loop to ensure the electroplating.
3) Plating
Generally, copper, nickel and chromium are used to electroplating on the surface of plastic parts to form a surface decorative layer. As shown in the figure, the common coatings after electroplating are mainly three metal deposition layers of copper, nickel, and chromium. Under ideal conditions, the common thickness of each layer is shown in the figure, and the overall thickness is about 0.02mm.