Painting & Coating
Imparting premium aesthetics and advanced functional resistance onto molded plastics requires high-performance liquid spray painting and protective coating systems. From velvet-like soft-touch polyurethane (PU) coatings to scratch-resistant, fast-curing UV clear coats and metallic-feel paints, these finishes elevate both the tactile experience and environmental durability of components. At Jucheng Precision, we operate dust-free paint lines to prevent particulate contamination. We strictly manage substrate surface energies and pre-treatment protocols, utilizing RoHS and REACH compliant, low-VOC coatings to deliver pristine, high-adhesion finishes verified by cross-hatch tape testing.
Painting & Coating Systems & Functional Performance
Applying high-performance liquid spray coats onto molded plastics enhances both haptic premium feel and chemical/UV durability. We support multiple advanced coating systems:
| Coating Technology | Typical Coating Medium | Thickness & Hardness | Key Advantages & Applications |
|---|---|---|---|
| Soft-Touch PU | Polyurethane Velvet Co-polymer Paint | 15 – 25 µm / HB to F | Provides a warm, velvet-like rubbery feel with excellent grip. Used for gaming controllers, high-end car steering trims, and consumer electronics. |
| UV-Cured Clear Coat | Acrylate Ultraviolet-Hardened Varnish | 10 – 15 µm / 2H to 4H | Extreme scratch and abrasion protection, outstanding chemical resistance, and high-gloss retention. Applied in car dashboards and phone bodies. |
| Metallic & Ceramic Paint | Aluminum-Pigmented / Sol-Gel Coatings | 20 – 30 µm / H to 2H | Delivers authentic anodized metal or ceramic feels, completely covering weld lines. Used for cosmetic home appliances and auto exterior grilles. |
Substrate Surface Energy & Paint Adhesion Compatibility
Molded plastics possess different surface energies (dyne levels). Ensuring the substrate dyne level is higher than the paint’s surface tension is critical for adhesion:
| Polymer Substrate | Natural Surface Energy | Adhesion Compatibility & Pre-Treatment Needs |
|---|---|---|
| ABS / PC / PC-ABS | High (38 – 42 mN/m) | Excellent. Polar molecular structures support direct chemical adhesion of PU and UV paints without special flame pre-treatment. |
| PP / PE (Polyolefins) | Low (29 – 31 mN/m) | Poor. Non-polar chains require active flame, corona, or plasma treatment (raising dyne levels above 38 mN/m) and special chlorinated primers. |
| POM (Acetal) / Nylon (PA) | Medium to Low (33 – 36 mN/m) | Moderate. Crystalline slide-grade polymers have low surface friction, requiring surface acid etching or adhesion-promoter primers before coating. |
Molding Analysis: Coating Adhesion & Surface Activation Matrix
Securing flawless paint adhesion and bubble-free coatings requires deep-rooted expertise in polymer chemistry and sterile spray processing:
Mold Release Residue Mitigation
Silicone-based mold release agents used during injection molding form an invisible hydrophobic barrier that completely destroys paint adhesion, causing severe peeling or “fisheye” defects. Jucheng’s production lines enforce the use of silicone-free release agents, or subject parts to a chemical solvent wash before they enter the spray line.
Low Surface Energy Activation (Flame & Corona)
For non-polar polymers like PP (Borealis RF365MO), we implement automated flame or corona treatment. This process oxidizes the outer polymer skin, creating active polar sites (such as carbonyl and hydroxyl groups). This raises surface energy above 38 mN/m, ensuring a permanent chemical link with the paint layer.
Class 10,000 Dust-Free Spray Booths
Any microscopic airborne dust particulate will settle on wet paint, causing visible inclusions and ruined cosmetics on high-gloss UV surfaces. Jucheng operates all liquid painting processes inside certified Class 10,000 dust-free positive-pressure spray booths, supported by electrostatic de-dusting blowers.