News

Knowledge

Company News

Application Mind Map

Test Report

Technical Article

Industry News

Exploring the Coating Structure of UV Vacuum Plating

Release time:

2026-05-25 07:15

Exploring the Coating Structure of UV Vacuum Plating

The coating system produced by UV vacuum plating on non-metallic substrates such as plastics employs a multilayer architecture. This structure comprises a primer layer, a plating layer, and a topcoat; in some cases, an intermediate layer is added to meet more stringent performance requirements. Each layer is tailored in composition and function, working in concert to form a comprehensive performance chain that extends from the substrate to the surface. Understanding the structural characteristics and functional roles of each layer is fundamental to grasping the underlying principles of UV vacuum plating technology.

I. Primer Layer

The primer layer is the initial coating applied to the surface of the plastic substrate and serves as the foundation for the entire coating system. Its primary functions are to seal microscopic defects on the substrate surface, enhance adhesion between the plating layer and the substrate, and provide a smooth, even base for subsequent coating applications.

From a compositional standpoint, primers typically use polyurethane acrylates as the base resin, supplemented with adhesion promoters and leveling agents. Polyurethane acrylates strike a favorable balance among flexibility, leveling, and adhesion. Phosphate ester compounds in the adhesion promoter can form chemical bonds with polar functional groups on the substrate surface, thereby enhancing interfacial adhesion. Meanwhile, leveling agents ensure that the primer spreads evenly before curing, yielding a smooth, uniform surface.

II. Coating Layer

The coating layer is a metallic film formed on the primer surface via vacuum deposition and serves as the core layer of the entire coating system. Its primary function is to impart a metallic luster, giving the plastic substrate an appearance that closely resembles metal.

The coating material is primarily high-purity metallic aluminum, which is widely used due to its low evaporation temperature, excellent adhesion, high reflectivity, and low cost. The coating layer is formed through a physical vapor deposition process: under vacuum conditions, the metal is vaporized and deposited onto the primer surface, creating an extremely thin, continuous film. The coating thickness typically ranges from 0.01 to 0.1 micrometer—very thin yet sufficient to produce a metallic luster. Magnetron sputtering offers greater technical advantages, as it yields dense coatings with strong adhesion.

III. Topcoat Layer

The topcoat is the outer layer applied over the coating system and serves as the protective barrier for the entire coating. Its primary function is to shield the underlying metallic coating from external abrasion and chemical corrosion, while also enabling a wide range of color effects as required.

From a compositional standpoint, topcoats typically employ high‑functionality polyurethane acrylates as the base resin to achieve a high crosslink density and superior surface hardness, thereby imparting excellent wear resistance and scratch resistance. Topcoats can be colored according to product design requirements, with a wide range of color effects achieved by adding colorants or pigments. Some topcoat formulations are non‑wipeable; after curing, they form a non‑sticky surface that requires no cleaning‑agent wiping.

IV. Intermediate Coating

To meet higher performance requirements, some UV vacuum‑plating systems also incorporate an intermediate coating. Positioned between the primer and the topcoat, this intermediate layer is designed to enhance the overall performance of the coating system. It further fills microscopic defects on the primer surface, providing a smoother substrate while improving adhesion between the topcoat and the primer. Although introducing an intermediate coating adds process steps and costs, it can significantly boost the system’s overall performance, making it well suited for applications with stringent durability demands.

V. The Collaborative Relationships Among Different Levels

The multilayer structure of UV vacuum plating is not merely the simple sum of the functions of each layer; rather, it arises from the coordinated interplay and synergistic effects among the layers. The smooth, even surface of the primer provides an excellent reflective substrate for the coating layer, while the metallic luster of the coating layer shines through the transparent topcoat, and the topcoat’s clear protective film preserves the metallic texture without obscuring it. This three‑layer architecture achieves functional complementarity: the primer ensures adhesion, the coating delivers decorative appeal, and the topcoat offers protection. The quality of each layer directly influences the overall performance, so the process parameters for every layer must be rigorously controlled.

VI. Conclusion

The coating structure of UV vacuum plating employs a three‑layer design—primer, metallic coating, and topcoat—each layer with clearly defined functions that work in concert. The primer ensures adhesion and surface leveling; the metallic coating delivers a metallic sheen and serves as the visual centerpiece; and the topcoat provides wear resistance and color decoration. An optional intermediate layer can further enhance overall performance. Interfacial bonding between the layers is achieved through chemical bonding and mechanical anchoring, creating a seamless performance continuum from the substrate to the surface. Understanding the design rationale behind this multilayer architecture is critical for process engineering and quality control.

Disclaimer: The above content has been compiled from publicly available sources and is provided for reference only. If any infringement occurs, please contact us, and we will address it promptly.

Bosheng Related Product Recommendations – Vacuum Plating
Primer
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, containing 20% TPGDA.
B-151	Modified epoxy acrylate	Low halogen, yellowing-resistant, excellent plating performance, and strong adhesion.
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
B-163	Modified epoxy acrylate	Good flexibility, excellent pigment wetting, and strong adhesion.
B-165	Modified epoxy acrylate	Good flexibility and strong adhesion
B-212A	Aromatic polyurethane acrylate	High cost-performance, excellent plating adhesion, good toughness, and resistant to boiling water.
B-221	Aliphatic polyurethane acrylate	Fast curing, resistant to boiling water
B-268M	Aliphatic polyurethane acrylate	Good flexibility, excellent adhesion, superior plating performance, and strong hiding power.
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV.
B-619W	Aliphatic polyurethane acrylate	Fast curing, high hardness, excellent toughness, wear resistance, and chemical resistance.
Intermediate coat
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-374	Aliphatic polyurethane acrylate	Excellent flexibility, good leveling, resistant to abrasion and chemicals, and resistant to yellowing.
B-601	Aromatic polyurethane acrylate	High hardness, scratch resistance, chemical resistance, and excellent cost-effectiveness.
B-6020	Special functional group acrylate	Resistant to boiling water, excellent color development, and strong interlayer adhesion.
Topcoat
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-221	Aliphatic polyurethane acrylate	Fast curing, resistant to boiling water
B-301	Aromatic polyurethane acrylate	Fast curing, excellent toughness, and good sandability.
B-302	Aromatic polyurethane acrylate	Fast curing, high strength, excellent toughness, and good grindability.
B-368	Aliphatic polyurethane acrylate	Good toughness, excellent leveling, excellent bend resistance, and excellent heat resistance.
B-374	Aliphatic polyurethane acrylate	Excellent flexibility, good leveling, resistant to abrasion and chemicals, and resistant to yellowing.
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV.
B-601	Aromatic polyurethane acrylate	High hardness, scratch resistance, chemical resistance, and excellent cost-effectiveness.
B-6016C	Special functional group acrylate	Easy to apply, resistant to yellowing and boiling water, and improves the appearance of the paint film.
B-6019	Special functional group acrylate	Good leveling, excellent wettability, resistant to boiling water, and superior color dispersion.
B-609	Aliphatic polyurethane acrylate	Fast curing, high hardness, scratch resistance, and chemical resistance.
B-615A	Aliphatic polyurethane acrylate	Fast curing, excellent toughness, wear resistance, and chemical resistance.
B-619W	Aliphatic polyurethane acrylate	Fast curing, high hardness, excellent toughness, wear resistance, and chemical resistance.
B-6210	Aliphatic polyurethane acrylate	Low viscosity, chemical resistance, environmental resistance, and dual photothermal curing.
B-6211	Aliphatic polyurethane acrylate	Fast curing, high hardness, scratch-resistant, and free of organotin.
B-919B	Aliphatic polyurethane acrylate	Fast curing, high hardness, excellent toughness, and outstanding chemical and wear resistance.
Monomer Recommendation
Product Model/English Abbreviation	Product Name/Product Type	Product Features
BM2223 (TPGDA)	Di(propylene glycol) diacrylate	Good flexibility and low volatility
BM3231 (TMPTA)	Trimethylolpropane triacrylate	High crosslink density, high hardness, high gloss, and excellent wear resistance.
BM3235 (PET3A)	Pentaerythritol triacrylate	Fast curing, high crosslink density, high hardness, and chemical resistance.
BM3380 (3EO-TMPTA)	Pentaerythritol triacrylate	More flexible and less irritating than TMPTA.
BM6261 (DPHA-80)	Dipentaerythritol hexaacrylate	High crosslink density, high hardness, chemical and wear resistance, and water resistance.
BM6263 (DPHA-90)	Dipentaerythritol hexaacrylate	High crosslink density, high hardness, chemical and wear resistance, and water resistance.

Share to:

Analysis of the Process Flow for UV Vacuum Plating

Analysis of the Core Components of UV Vacuum Plating