Tinuvin 928 Equivalent For Automotive Coatings | CAS 73936-91-1
Technical Specifications and CAS Number Verification for Tinuvin 928 Equivalents
Verification of chemical identity for UV Absorber 928 begins with strict adherence to CAS 73936-91-1. This benzotriazole UV absorber is chemically defined as 2-(2H-Benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol. R&D teams requiring a drop-in replacement must validate batch-specific COAs against critical physical constants to ensure performance parity in high-solid systems. The molecular weight of 441.6 g/mol dictates solubility profiles in aromatic and polar solvents commonly used in automotive refinish and OEM clear coats.
Quality control parameters focus on purity levels exceeding 98.5% via HPLC analysis to minimize impurities that could catalyze premature degradation. Transmittance values at 460nm and 500nm are critical for maintaining color clarity in light-colored formulations. NINGBO INNO PHARMCHEM CO.,LTD. maintains rigorous internal standards for ash content and loss on drying to prevent volatility issues during high-temperature curing cycles. The following table outlines the standard technical specifications required for qualification:
| Parameter | Specification Standard | Test Method |
|---|---|---|
| Chemical Name | 2-(2H-Benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol | MS / NMR |
| CAS Number | 73936-91-1 | Verification |
| Appearance | Yellow Powder | Visual |
| Purity (HPLC) | ≥ 98.5% | Area Normalization |
| Melting Point | 108-110°C | DSC / Capillary |
| Loss on Drying | ≤ 0.3% | 105°C / 2h |
| Ash Content | ≤ 0.1% | Gravimetric |
| Transmittance (460nm) | ≥ 95% | UV-Vis Spectrophotometry |
| Transmittance (500nm) | ≥ 97% | UV-Vis Spectrophotometry |
Consistency in these metrics ensures the Benzotriazole UV Absorber functions predictably within complex resin matrices. Deviations in melting point often indicate isomeric impurities that can alter compatibility with polyurethane prepolymers.
Compatibility Testing in 2K Polyurethane and High-Solid Automotive Clear Coats
Integration of UV-928 into 2K polyurethane systems requires assessment of solubility limits and interaction with isocyanate hardeners. High-solid automotive clear coats operate with reduced solvent volumes, increasing the risk of additive precipitation during storage or cure. The steric hindrance provided by the tetramethylbutyl and phenylethyl groups enhances solubility in standard automotive solvent blends such as xylene, butyl acetate, and methoxy propyl acetate.
Compatibility testing involves monitoring haze development and solution stability over accelerated storage conditions at 50°C. In high-solid formulations, the additive must remain molecularly dispersed to prevent surface defects like cratering or orange peel. The chemical structure supports stability in solvent-based systems while maintaining low volatility. For formulators exploring alternative applications, reviewing the UV Absorber 928 Powder Coating Formulation Guide provides additional context on thermal stability limits during extrusion and cure, which correlates to high-temperature solvent bake schedules.
Interaction with resin components such as acrylic polyols and polyester polyols is generally inert, but verification via viscosity stability tests is recommended. The additive does not interfere with the catalysis of the isocyanate-hydroxyl reaction, ensuring pot life remains within specified windows. This makes it suitable for both high-performance OEM lines and repair refinish applications where consistent flow-out is critical.
Performance Validation of Tinuvin 928 Equivalents in Accelerated Weathering Tests
Validation of light stability requires exposure to cyclic UV and moisture conditions simulating long-term outdoor weathering. The primary function of CAS 73936-91-1 is to absorb harmful UV radiation in the 300-400nm range, converting it into harmless thermal energy. Performance benchmarks are measured via gloss retention, color change (Delta E), and crack resistance after extended exposure in QUV or Xenon arc chambers.
Data indicates that equivalent grades must match the absorption profile of the market standard to prevent substrate degradation. In automotive clear coats, failure to absorb specific UV wavelengths leads to polymer chain scission, resulting in gloss loss and chalking. Detailed UV Absorber 928 Performance Benchmark Data Analysis confirms that high-purity equivalents maintain gloss levels above 80% after 2000 hours of QUV exposure when properly stabilized. Synergy with hindered amine light stabilizers (HALS) is essential for maximizing durability.
Testing protocols should include both direct exposure and back-iron scenarios to evaluate adhesion retention. Color stability is particularly vital for metallic and solid white finishes where yellowing of the additive itself must be minimized. The transmittance specs listed in the technical table ensure minimal initial color contribution, preserving the aesthetic quality of the topcoat. R&D teams should validate these parameters against their specific resin systems to confirm equivalence.
Optimal Dosage Rates and Formulation Guidelines for Solvent and Water-Based Systems
Effective stabilization depends on precise dosage rates relative to the total solid content of the formulation. For most high-performance automotive coatings, the recommended loading of UV Absorber 928 ranges from 1.0% to 3.0% by weight of the total resin solids. Lower dosage rates may suffice in thin-film applications, while thicker clear coats require higher concentrations to ensure sufficient optical density throughout the film thickness.
In solvent-based systems, the additive should be dissolved into the resin solution prior to the addition of the hardener to ensure complete homogeneity. For water-based systems, solubility is limited; therefore, this benzotriazole derivative is primarily suited for solvent-borne or high-solid applications unless emulsified specifically. When used in conjunction with HALS such as HALS-292 or HALS-123, synergistic effects significantly extend the service life of the coating. The HALS component scavenges free radicals generated during photo-oxidation, while the UV absorber prevents the initiation of degradation.
Formulators seeking a verified UV Absorber 928 drop-in replacement should adjust total stabilizer packages to maintain the balance between UV absorption and radical scavenging. Over-stabilization can lead to surface tackiness or interference with crosslinking density, so stepwise dosage optimization is recommended during pilot trials. Always verify compatibility with specific catalysts used in the curing process.
Supply Chain Security and IMDS Regulatory Compliance for Automotive OEMs
Automotive OEMs require strict adherence to supply chain security and material data reporting. Compliance with the International Material Data System (IMDS) is mandatory for all components entering the automotive supply chain. NINGBO INNO PHARMCHEM CO.,LTD. provides full IMDS data sheets including chemical composition, CAS numbers, and recyclability codes to facilitate seamless approval processes. Documentation must accurately reflect the chemical identity without disclosing proprietary trade secrets that violate reporting standards.
Supply chain security involves ensuring batch-to-batch consistency and traceability from raw material synthesis to final packaging. Packaging options typically include 20kg or 25kg cartons or drums, sealed to prevent moisture uptake which can affect flow properties. Lead times and inventory stability are critical for just-in-time manufacturing environments. Regulatory compliance focuses on accurate chemical listing rather than specific regional certifications that may change.
Procurement teams should verify that all shipments include batch-specific COAs matching the IMDS submission. This ensures that the material received matches the data approved by the OEM engineering teams. Consistency in physical form (powder vs. granule) and particle size distribution also impacts handling safety and dispersion efficiency in automated dosing systems. Secure logistics and documented chain of custody protect against contamination and ensure material integrity upon arrival at the coating facility.
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