# Product Name
**SMP PPGI (Silicone-Modified Polyester Prepainted Galvanized Steel Coil)**
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## 1. Product Overview
SMP PPGI is a type of color-coated steel coil that is produced by coating a hot-dip galvanized or galvanized-aluminized substrate with a silicone-modified polyester (SMP) topcoat and then baking it for curing. Compared to regular polyethylene (PE), SMP exhibits superior weather resistance, resistance to powdering, and gloss retention, while maintaining good formability and a high cost-performance ratio. It is a commonly used color steel variety for medium to high weather resistance in construction and decoration applications.
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## 2. Substrate and Coating System (Typical)
* **Base material**: cold-rolled steel coil (common grades include DX51D / SGCC / equivalent CR steel), or aluminum-zinc coated base material (such as AZ type).
* **Galvanizing grade**: Commonly seen are Z60, Z120, Z180, Z275 (determined as needed), or Galvalume may be used as a substitute for high temperature resistance or stronger corrosion resistance.
* **Surface pretreatment**: degreasing → chemical passivation (optional chromium-containing or chromium-free chemical passivation) → transition coating to ensure adhesion.
* **Coating structure** (example): Primer 5–8 µm + SMP Topcoat 18–30 µm + Backcoat 5–10 µm (Adjustable according to project requirements).
* **Topcoat type**: Silicon-modified polyester (SMP), or high-weatherability SMP or SMP/PVDF hybrid system can be used on critical projects to enhance durability.
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## 3. Typical specifications (customizable)
* **Substrate thickness**: 0.12 mm – 1.2 mm (commonly used: 0.3 / 0.35 / 0.4 / 0.47 / 0.5 / 0.6 mm)
* **Roll width**: 600 – 1250 mm (conventional 914 / 1000 / 1219 mm, can be slit)
* **Inner diameter (ID)**: 508 mm or 610 mm
* **Net weight per roll**: approximately 1.5 – 8 tons (depending on thickness and inner diameter)
* **Total coating thickness (typical)**: 20 – 45 µm (depending on the primer and topcoat system)
* **Color/Surface**: Standard RAL/BS/customized colors; the surface can be glossy, matte, embossed, imitation wood grain, brushed metal, etc
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## 4. Main performance and advantages
* **Weather resistance superior to ordinary PE**: SMP contains silicon-modified components, which can significantly improve resistance to powdering and UV resistance, making it suitable for medium to medium-high weather resistance scenarios.
* **Good formability**: Suitable for rolling, bending, corrugating, profile forming, and punching. The coating is less prone to cracking or peeling under reasonable inner bending radii.
* **Color and gloss stability**: It maintains color difference and gloss better than ordinary polyester in long-term outdoor use.
* **Good adhesion, flexibility, and impact resistance**: Meet the requirements of conventional T-bend, impact, and cross-cut tests (see inspection items).
* **High cost-effectiveness**: Compared to PVDF (fluorocarbon), it has lower costs, yet its weather resistance and aesthetics are comparable, making it suitable for projects with limited budgets but requiring good weather resistance.
* **Environmental protection options**: Chromium-free passivation, low VOC, or water-based primer systems can be adopted to meet green specifications.
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## 5. Routine Testing and Performance Indicators (typical values, subject to contract)
* **Coating adhesion (Cross-cut)**: Grade 0–2 (ISO/ASTM standard)
* **Flexibility (T-bend)**: 2T – 3T (depending on thickness and formulation)
* **Impact Test (Gardner)**: No cracking/peeling of topcoat (measured in mm·kg)
* **Salt spray corrosion (NSS)**: hundreds to thousands of hours (depending on the galvanizing grade and coating system; for example, Z120+SMP typically lasts 500–1000 hours, while Z275 or thicker coatings may last longer)
* **Weather resistance (QUV / artificial aging)**: The color and gloss change slowly, with the specific number of hours as agreed upon in the contract
* **Scratch resistance / Hardness**: Depending on the topcoat formula, it generally meets the requirements for regular assembly and on-site transportation
Note: The above are common industry ranges. The actual technical requirements (such as salt spray hours, QUV hours, ΔE maximum, etc.) should be specified in the technical agreement and serve as the acceptance criteria.
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## 6. Processing and Forming Recommendations (to Avoid Coating Damage)
* **Radius of curvature**: For small thicknesses (≤0.4 mm), it is recommended that the bending radius be ≥ 1.5–2 × the thickness of the substrate (as verified by process); for deep drawing/extremely small radii, process samples should be made.
* **Punching / Bending / Profiling**: Utilize passivation techniques, along with appropriate mold radii, lubrication, and controlled pressure, to minimize cracking and coating delamination.
* **Pre-coated part welding**: It is recommended to perform local grinding and paint repair in the welding area (select a compatible system for paint repair in the SMP area).
* **Roof corrugations/purlins**: Use the correct self-tapping screws and waterproof washers to avoid electrochemical corrosion caused by direct metal contact.
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## 7. Typical application scenarios
* **Building envelope**: roof panels, wall panels, horizontal cladding, cornices, and purlins (for moderate weather resistance scenarios).
* **Enclosure system**: door and window casings, eave gutters, roof gutters, and skylight accessories.
* **Secondary components of exterior decoration and curtain wall**: decorative panels, floodlight panels, and sheet metal components (not used on the main facade or in conjunction with PVDF).
* **Interior decoration and furniture**: Ceiling, partition, cabinet panel, and appliance casing (parts with low weather resistance requirements).
* **Others**: Lightweight interior lining of vehicles, billboard substrates, small containerized items, and equipment covers.
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## 8. Precautions for storage and handling
* Store the rolls in a dry and well-ventilated place, avoiding dampness and open storage.
* Prevent condensation inside the roll: When there is a large temperature difference, allow it to reach room temperature before unwrapping.
* Use soft slings or dedicated hooks for handling to avoid scratching the edges and surface of the roll with hard objects.
* When stored for a long time, place moisture-proof materials between rolls and avoid deformation due to heavy pressure.
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## 9. Packaging and labeling
* **Inner protection**: moisture-proof paper or VCI film.
* **Outer layer**: Steel strapping, corner protection, wooden pallets, or metal protective plates to protect the ends.
* **Label information**: product model (SMP PPGI), color code, coating system, galvanizing grade (Z value), substrate thickness, net weight, roll number, and production date.
* **Export packaging**: Reinforce and provide waterproof and salt-proof protection according to maritime transportation standards.
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## 10. Quality Control and Certification
* **Factory inspection**: coating thickness, adhesion, flexibility, salt spray/QUV (as per contract), appearance inspection (bubbles, pinholes, scratches).
* **Documentation**: Provide MTC (base material), coating inspection reports, and batch traceability information.
* **Optional**: Third-party inspection, on-site sampling, and specialized weathering/corrosion verification.
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## 11. Ordering Instructions (Please provide for quick and accurate quotation)
1. **Substrate thickness (mm)** and **Roll width (mm)**;
2. **Galvanizing grade** (Z60 / Z120 / Z180 / Z275 or Galvalume);
3. **Coating system and target topcoat thickness** (regular SMP / high-weather resistance SMP / SMP+ reinforced layer);
4. **Color (RAL / Sample)** and **Surface Effect** (Glossy / Matte / Embossed);
5. **Net weight per roll, preferred inner diameter, and packaging requirements**;
6. **Target performance** (e.g. salt spray 500/1000/2000 hours, ΔE ≤ a certain value, QUV hours, etc.);
7. **Processing technology** (whether deep drawing, minimum bending radius, corrugated model, etc.);
8. **Quantity, delivery location, and delivery date**, whether third-party inspection or on-site inspection is required.
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## 12. Comparison with other coatings (quick overview)
* **SMP vs PE**: SMP exhibits better weather resistance and gloss retention, albeit at a slightly higher price compared to regular PE.
* **SMP vs PVDF**: PVDF (fluorocarbon) excels in long-term weather resistance and color fastness compared to SMP, but its cost is significantly higher; SMP represents a cost/performance compromise, making it suitable for most mid-to-high-end projects.
* **SMP + Z275**: Suitable for coastal or harsh outdoor environments, offering a balance between edge sacrifice protection and topcoat weatherability.
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## 13. Frequently Asked Questions (FAQ)
* **Q: Can SMP PPGI be used for long-term outdoor roofing?**
A: It can be used for long-term outdoor applications, but it is recommended to select the appropriate galvanizing grade (Z180/Z275) and high-weatherability SMP or upgrade to PVDF based on the specific environment (coastal/industrial).
* **Q: Can deep drawing or complex forming be done?**
A: Yes, but we need the molded drawing and the minimum bending radius to confirm the coating adaptability of the sample.
* **Q: What is the typical lifespan of an SMP?**
A: It is affected by the amount of galvanizing on the substrate, the formulation of the topcoat, and the environment; generally longer than PE, and can last for several years to over a decade in mild environments; the specific lifespan should be based on accelerated aging and on-site experience, and the acceptance requirements should be clearly specified in the contract.
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If you need, I can provide it for you immediately (choose one and generate it immediately):
* **A one-page technical specification sheet (PDF or tabular format)**, including the roll yield and unit weight for the selected thickness/width;
* **Molding Process Proposal**, including minimum bending radius, recommended mold parameters, and sample plan; or
* **Provide configuration recommendations and expected maintenance intervals for SMP+ galvanizing grades based on different environments (inland / urban / coastal / industrial).**.
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