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In-Depth Introduction to Hydrophobic Fumed Silica Grades R972, R974, and H18 and Their Downstream Applications
创建于04.22
In-Depth Introduction to Hydrophobic Fumed Silica Grades R972, R974, and H18 and Their Downstream Applications
I. Technical Parameters and Performance Comparison of Grades
Grade | R972 (Evonik) | R974 (Evonik) | H18 (Wacker) |
Chemical Name | Hydrophobic Fumed Silica | Hydrophobic Fumed Silica | Hydrophobic Fumed Silica |
Surface Treatment | Dimethyldichlorosilane (DMCS) | Hexamethyldisilazane (HMDS) | Polydimethylsiloxane (PDMS) |
Specific Surface Area (BET) | 170-200 m²/g | 200-250 m²/g | 180-220 m²/g |
Primary Particle Size | 16 nm | 7 nm | 7 nm |
Bulk Density | 50 g/L (loose state) | 40 g/L (loose state) | 50 g/L (loose state) |
pH Value (10% Aqueous Dispersion) | 3.7-4.7 | 4.0-5.0 | 4.5-5.5 |
Contact Angle | >150° (completely hydrophobic) | >160° (super-hydrophobic) | >155° (strongly hydrophobic) |
Oil Absorption Value (DBP Method) | 2.0-2.5 mL/g | 2.8-3.2 mL/g | 2.3-2.7 mL/g |
Thermal Stability | Resistant to 200°C | Resistant to >300°C | Resistant to 250°C |
II. Core Performance Advantages Analysis
1. R972: All-Round Hydrophobic Agent for Low-Viscosity Systems
- Advantages
- Limitation
2. R974: Thickening Expert for High-Temperature and Polar Systems
- Advantages
- Limitation
3. H18: Industrial-Grade Additive Balancing Thixotropy and Lubricity
- Advantages
- Limitation
III. Downstream Application Scenarios and Selection Guide
1. Rubber and Elastomer Industry
Application Scenario | Recommended Grade | Mechanism | Addition Rate | Typical Cases |
Silicone Rubber (RTV/HTV) | R972 | Provides hydrophobicity, enhances moisture resistance and tear strength | 1-3% | Bathroom sealants, electronic potting compounds |
High-Temperature Vulcanized Rubber | R974 | Enhances structural stability at high temperatures, inhibits filler sedimentation | 2-5% | Automotive engine seals, oven rubber pads |
Rubber Composites | H18 | Improves filler dispersion, reduces mixing torque | 0.5-2% | Tire sidewalls (enhanced ozone crack resistance) |
2. Coatings and Ink Industry
Application Scenario | Recommended Grade | Core Function | Technical Index Optimization | Typical Formulations |
Solvent-Based Anticorrosive Coatings | R974 | Prevents pigment sedimentation, provides thixotropy to resist sagging | Sagging <1mm (ISO 1520 standard) | Marine paints, steel structure coatings |
UV-Curable Inks | H18 | Prevents pigment flocculation, improves film smoothness | Surface friction coefficient reduced by 30% | Metal printing inks, label inks |
High-Temperature Ceramic Coatings | R974 | Withstands >300°C, maintains coating integrity | Thermal weight loss <2% (300°C/2h) | Oven interior coatings, exhaust pipe heat-resistant coatings |
3. Adhesives and Sealants
Application Scenario | Recommended Grade | Key Performance Improvement | Test Standard | Typical Applications |
MS Polymer Adhesives | R974 | Prevents sagging (vertical construction), enhances initial tack | Sagging ≤3mm (ASTM D2202) | Building curtain wall seals, interior decoration adhesives |
Anaerobic Adhesives | H18 | Adjusts thixotropy for gap filling | Viscosity adjustable: 500-5000 mPa·s | Mechanical part locking adhesives, thread sealants |
Food-Grade Adhesives | R972 | Hydrophobic anti-caking, complies with FDA 21 CFR 172.480 | Heavy metal content <10ppm | Gummy coating adhesives, capsule lubricants |
4. Plastics and Composites
Application Scenario | Recommended Grade | Modification Effect | Processing Parameter Optimization | Typical Products |
Polyolefins (PE/PP) | H18 | Reduces melt viscosity, improves extrusion stability | Melt index increased by 15% (ISO 1133) | Plastic pipes, injection-molded parts (e.g., trash cans) |
Engineering Plastics (PA/PC) | R974 | Enhances interfacial compatibility, improves impact resistance | Notched impact strength +20% (ISO 179) | Automotive components, electronic casings |
Degradable Plastics | R972 | Prevents filler agglomeration, improves degradation uniformity | Elongation at break retention >85% | Agricultural mulch films, disposable tableware |
5. Specialized Applications
Scenario | Grade | Unique Value | Industry Standards |
Lithium Battery Electrode Slurries | H18 | Thickens to prevent sedimentation, improves coating uniformity | Slurry viscosity fluctuation ≤±5% |
Cosmetic Powders (Eye Shadow/Face Powder) | R972 | Hydrophobicity enhances skin adhesion, prevents caking | Compliant with Cosmetic Safety Technical Specifications |
Aerospace Sealants | R974 | Resists fuel corrosion, maintains elasticity at high temperatures | Certified to ASTM D2000 aerospace material standards |
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