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Detailed Explanation of the Composition of Three-Proof Coating Raw Materials

Release time:

2025-05-11 10:54

Detailed Explanation of the Composition of Three-Proof Coating Raw Materials
Detailed Explanation of the Composition of Three-Proof Coating Raw Materials

As a critical protective material, conformal coating plays an irreplaceable role in the fields of electronic manufacturing and industrial protection. It provides triple protection—moisture resistance, mold prevention, and salt-spray resistance—to electronic components and various precision devices, effectively extending product lifespans and ensuring stable operation even under complex and harsh environmental conditions. The outstanding performance of conformal coatings largely depends on the careful formulation and scientific composition of their raw materials. The following sections will provide a detailed analysis of the composition of conformal coating raw materials.

I. Resin Matrix

As the film-forming base of conformal coatings, the molecular structure of the resin directly determines the coating’s weather resistance, flexibility, and chemical stability. Different resins exhibit differentiated advantages in terms of protective performance, depending on the polarity of their functional groups, crosslinking density, and crystalline morphology.

1. Acrylic resin

Acrylic resins have a linear chain segment formed by the copolymerization of vinyl and carboxyl groups as their backbone. The polarity of the ester groups in the molecular chains imparts excellent flexibility and adhesion to these resins. Their curing process primarily involves solvent evaporation, enabling rapid film formation at room temperature, making them well-suited for automated coating lines with high production efficiency requirements. However, the ester groups are susceptible to attack by strong acids and strong bases, which may lead to swelling under extreme chemical conditions. Additionally, the molecular chains lack sufficient rigidity, resulting in relatively poor scratch resistance.

2. Fluorocarbon resin

Fluorocarbon resins have a main chain composed of carbon-fluorine bonds. Due to the large radius and high electronegativity of fluorine atoms, these bonds create a dense electron cloud barrier. This unique molecular structure endows fluorocarbon resins with exceptional chemical inertness and superior surface hydrophobicity, enabling them to resist erosion by most organic solvents and strong oxidizing agents. With low surface energy, contaminants find it difficult to adhere to the surface, making these resins ideal for protecting outdoor electronic devices. However, their high crystallinity results in poor solubility, requiring special solvents and elevated temperatures to achieve uniform coating. Moreover, during the curing process, pinhole defects tend to form easily, necessitating strict control of process parameters.

3. Polyurethane resin

Polyurethane resins are formed through the polymerization reaction between isocyanates and polyols, featuring both hard segments composed of urethane linkages and soft segments made of polyethers or polyesters within their molecular chains. This biphasic structure imparts excellent mechanical properties and outstanding low-temperature stability. The hard segments create physical crosslinks, resulting in high tensile strength of the coating; while the soft segments provide space for deformation, enabling the material to withstand mechanical impacts. However, their high-temperature resistance is limited, making them unsuitable for prolonged use at elevated temperatures. Moreover, polyester-based polyurethanes are susceptible to hydrolysis and thus require complementary moisture-proof measures when used.

4. Silicone resin

Silicone resins have a main chain composed of silicon-oxygen bonds, and the organic groups attached to silicon atoms impart unique surface properties. Their key advantages lie in their broad temperature-range stability and excellent electrical insulation performance. The bond energy of the silicon-oxygen bond is higher than that of the carbon-carbon bond, enabling these resins to maintain long-term stability at high temperatures without degradation. Moreover, their dielectric constant and tangent of the loss angle remain stable over a wide temperature range, making them ideal for protecting high-voltage electronic components. However, their curing process is relatively lengthy, typically requiring more than 24 hours; heating can shorten this curing time to as little as 2 hours.

II. Solvent

Solvents directly affect the film-forming quality and application efficiency of coatings by dissolving resins and adjusting the viscosity of the system. Based on their evaporation rates and solubility, solvents can be classified into volatile solvents and reactive diluents.

1. Volatile solvent

Low-boiling-point solvents—such as toluene and xylene—achieve surface drying through rapid evaporation and are suitable for dip-coating processes. However, it’s essential to control ambient humidity to prevent moisture from seeping in and causing the coating to turn whitish.

High-boiling-point solvents—such as butyl acetate and butyl carbitol—extend the application window and help prevent sagging. However, they may also increase curing time, so it’s important to strike a balance between production efficiency and coating quality.

2. Reactive diluent

Monofunctional diluents—such as isobornyl acrylate—participate in the free-radical polymerization of resins, reducing system viscosity while increasing cross-linking density. However, their addition levels must be carefully controlled to avoid compromising the flexibility of the coating.

Multifunctional diluents—such as trimethylolpropane triacrylate—accelerate curing by increasing the number of reaction sites; however, they tend to cause localized stress concentrations. Therefore, they should be used in conjunction with silicone-based leveling agents to relieve stress and prevent cracking of the coating.

III. Functional Additives

Additives, when added in trace amounts, can significantly enhance specific properties of coatings; their mechanisms of action involve intermolecular interactions and surface physicochemical regulation.

1. Flow control agent

Silicone-based leveling agents: By migrating to the coating surface, they reduce the surface tension gradient, thereby improving the smoothness of the coating surface.

Fluorocarbon leveling agents: Achieve ultra-hydrophobicity by forming oriented fluorocarbon chains on the coating surface, while also providing both leveling and dual anti-fouling properties.

2. Matting agent

Silica fume: By controlling particle size, a matting effect can be achieved, but a trade-off between optical and mechanical properties must be considered.

Wax-based additives: Achieve matte finish through a micro-convex structure formed after melting. They are suitable for matte finishing, but excessive use can lead to reduced adhesion.

3. Adhesion Promoter

Silane coupling agents: The silanol groups generated through hydrolysis form covalent bonds with the hydroxyl groups on the substrate surface, thereby enhancing adhesion.

Phosphate ester additives: They undergo a chelation reaction with the oxide layer on the surface of metal substrates, forming chemical bonds at the interface.

4. Anti-aging agent

Hindered amine light stabilizers: By scavenging free radicals and decomposing peroxides, they extend the half-life of photoaging.

UV absorbers: They convert ultraviolet light into thermal energy and release it, but may reduce the weather resistance of the coating; therefore, they should be used in combination with other additives.

IV. Summary

In summary, the composition of conformal coating materials resembles a complex and sophisticated system, in which resins, solvents, and functional additives each play an indispensable role. A deep understanding of the composition of conformal coating materials provides us with ample room for optimization in both production and application. By precisely controlling the types and proportions of these raw materials, we can deliver more reliable and efficient protective solutions for the fields of electronic manufacturing and industrial protection.

Bossin Related Product Recommendations

UV-resistant, moisture-proof, and anti-corrosion coating

Product Type

Product Features

Application areas

B-02 (Phosphate Acrylate)

Enhance adhesion to substrates such as metal, glass, and plastic.

Vacuum-plated UV coatings, metallic UV varnishes, UV adhesives, UV inks

B-404 (Aliphatic Polyurethane Acrylate)

Good adhesion, moisture-cured

UV-resistant, anti-corrosion, and anti-moisture coating; self-adhesive; dual-curing

B-405 (Aliphatic Polyurethane Acrylate)

Good adhesion, moisture-cured

UV-resistant, three-proof coating, dual-cure

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