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The production of PVDF-coated aluminum coil has higher technical requirements than ordinary coated aluminum coils, especially in coating formulation and curing process. The main steps are as follows:
Select high-purity aluminum coils with excellent surface quality, such as 1060, 3003, 5052, and 6061 alloys. The substrate's surface flatness, thickness uniformity, and impurity content are strictly controlled to avoid affecting the coating adhesion and appearance.
This is the basis for ensuring long-term adhesion of PVDF coating, including three key links:
Use alkaline degreasing agents and ultrasonic cleaning technology to completely remove oil, dust, and oxide layers on the aluminum coil surface, ensuring no residual contaminants.
Adopt zirconium-based or titanium-based environmental protection conversion agents (replacing traditional chromate conversion) to form a dense, uniform conversion film with a thickness of 0.5-1 μm, which enhances the bonding force between the substrate and the coating.
Dry the pretreated aluminum coil at 100-120 °C to remove surface moisture, ensuring the conversion film is stable and not damaged.
Use multi-layer roller coating technology, usually including primer, topcoat, and optional backcoat. The PVDF content in the topcoat is ≥70% (meeting AAMA 2605 standard). The coating thickness is precisely controlled: primer 5-10 μm, topcoat 20-30 μm, backcoat 5-10 μm. The roller coating speed and pressure are adjusted in real-time to ensure uniform coating thickness.
Send the coated aluminum coil to a high-temperature curing oven with precise temperature control. The curing temperature is 230-250 °C, and the curing time is 25-35 minutes. This process promotes the cross-linking polymerization of PVDF resin, forming a dense and stable coating structure.
Conduct comprehensive testing of key indicators, including coating thickness (using a coating thickness gauge), adhesion (cross-cut test ≥5B), pencil hardness (≥3H), color difference (ΔE ≤ 1.0), weather resistance (QUV aging test ≥3000 hours), and corrosion resistance (neutral salt spray test ≥1500 hours). Unqualified products are strictly eliminated.
According to customer needs, slit the qualified PVDF-coated aluminum coil into coils of different widths, and use moisture-proof, scratch-resistant packaging materials (such as PE film, corrugated cardboard, and wooden pallets) for packaging to ensure product integrity during transportation.
PVDF-coated aluminum coil specifications are customized according to high-end application scenarios and performance requirements. The main specifications are shown in the following table:
| Specification Category | Detailed Parameters | Typical Applications | Quality Control Requirements |
|---|---|---|---|
| Substrate Thickness | Thin: 0.2mm - 0.5mm | High-end home appliance panels (high-end refrigerator doors, air conditioner casings), precision signage | Thickness deviation ≤±0.02mm, surface roughness Ra ≤0.3μm |
| Medium: 0.5mm - 1.5mm | High-end architectural decoration (curtain walls, exterior wall cladding, elevator doors), advertising light boxes for harsh environments | Thickness deviation ≤±0.03mm, flat surface without waves or scratches | |
| Thick: 1.5mm - 4.0mm | Transportation (high-speed rail interior/exterior trim, ship hull cladding), industrial equipment casings | Tensile strength ≥180MPa, elongation ≥5%, good stamping performance | |
| Coating Parameters | Standard Coating: Total thickness 30-40μm (primer 5-10μm, topcoat 20-25μm, PVDF content ≥70%) | High-end architectural curtain walls, coastal building exterior cladding, medium-sized industrial equipment | Adhesion ≥5B, QUV aging test ≥3000h, color difference ΔE ≤1.0 |
| Heavy Coating: Total thickness 40-60μm (primer 10μm, topcoat 25-35μm, backcoat 5-10μm, PVDF content ≥75%) | Harsh environments (offshore platforms, chemical plant walls, desert area buildings) | Neutral salt spray test ≥3000h, weather resistance test ≥5000h, pencil hardness ≥3H | |
| Width & Length | Standard Width: 1000mm, 1220mm, 1500mm, 1600mm, 1800mm | Batch production of high-end architectural materials, home appliances, and transportation parts | Width deviation ≤±0.5mm, no edge warping or coating accumulation |
| Custom Width: 600mm - 1800mm; Length: 500-5000kg/roll | Special architectural projects (large-span curtain walls), customized industrial equipment | Uniform coil tension, no creases, coating thickness variation ≤±2μm | |
| Alloy Types | 1060 Alloy (≥99.6% Al) | High-end indoor decoration, precision home appliance panels | Excellent ductility, surface flatness ≤0.1mm/m |
| 3003 Alloy (Mn 1.0-1.5%) | Coastal architectural decoration, industrial equipment casings | Enhanced corrosion resistance, tensile strength ≥150MPa | |
| 5052/6061 Alloy (Mg 2.2-2.8%/Al-Mg-Si alloy) | Transportation parts, high-stress architectural components, offshore platforms | High strength, good fatigue resistance, marine corrosion resistance |
For high-end B2B and architectural applications, the PVDF content in the topcoat must be ≥70% to meet the AAMA 2605 industry standard. For heavy-duty settings, it can be increased to ≥75%.
Typical alloys include 1060 (high ductility for decoration), 3003 (excellent corrosion resistance for architectural cladding), and 5052/6061 (high strength for marine and transportation structures).
Quality testing involves validating coating thickness, adhesion (cross-cut test ≥5B), pencil hardness (≥3H), color difference (ΔE ≤ 1.0), weather resistance (QUV aging ≥3000 hours), and corrosion resistance (salt spray test ≥1500 hours).
Standard coating has a thickness of 30-40μm, suitable for general facades and equipment. Heavy coating has a thickness of 40-60μm, designed to withstand harsh environments like offshore platforms and chemical plants.
Precision surface pretreatment is applied, which includes degreasing, ultrasonic cleaning, and environmentally-friendly chemical conversion treatment (zirconium- or titanium-based film of 0.5-1μm) to maximize coating adhesion.
The coated aluminum coil is sent to a high-temperature curing oven at 230-250 °C for 25-35 minutes to achieve proper cross-linking polymerization of the PVDF resin.
