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HDK N20 is a high-purity, hydrophilic, amorphous fumed (pyrogenic) silica produced by flame hydrolysis of silicon tetrachloride.
It functions as a highly effective rheology modifier, thickener, anti-settling agent, and free-flow additive in industrial formulations.
Manufactured by Wacker, HDK N20 is a standard grade widely used across coatings, printing inks, adhesives, elastomers, and cosmetics.
CAS Number: 112945‑52‑5
EC Number: 310‑127‑6
Molecular Formula: SiO₂
Molecular Weight: ≈ 60.08 g/mol
Synonyms: Fumed Silica, Hydrophilic Amorphous Silica, Pyrogenic Silica, Silica (INCI), Wacker HDK N20, Silicon Dioxide Thickener/Thixotrope, HDK N20, HDK N‑20, HDK® N20, HDK® N‑20, Wacker HDK N20, Synthetic Hydrophilic Fumed Silica, Pyrogenic Silica N20, Amorphous Silica N20, Fumed Silica N20, Hydrophilic Silica, High-Purity Silica Powder, Silica Thickener N20, Silica Rheology Additive, Silica Thixotrope N20, Silica Rheology Modifier, Amorphous Fumed Silica, Flame‑Hydrolysis Silica, Silica Rheology Control, INCI Silica
APPLICATIONS
HDK N20 is used as a reinforcing filler in silicone rubber formulations.
HDK N20 is used to control rheology in sealants and adhesives.
HDK N20 is incorporated into epoxy systems to improve thixotropy.
HDK N20 is used in polyurethane coatings for scratch resistance.
HDK N20 is added to unsaturated polyester resins for sag control.
HDK N20 is used in cable compounds to enhance mechanical strength.
HDK N20 is employed in inks to improve print definition.
HDK N20 is used in PVC plastisols to reduce sedimentation.
HDK N20 is applied in paints to improve anti-settling properties.
HDK N20 is added to adhesives for vertical application capability.
HDK N20 is used in lubricants to improve dispersion stability.
HDK N20 is added to gelcoats for better surface hardness.
HDK N20 is used in cosmetic formulations to stabilize emulsions.
HDK N20 is incorporated into grease thickeners for enhanced performance.
HDK N20 is used in thermal insulation foams for fine pore structure.
HDK N20 is used in dental impression materials for dimensional stability.
HDK N20 is applied in synthetic resins for improved hardness.
HDK N20 is used in food packaging inks to improve clarity and control viscosity.
HDK N20 is used in coatings for electrical insulators.
HDK N20 is used in caulks to reduce slump and sagging.
HDK N20 is used in battery sealants for chemical resistance.
HDK N20 is applied in electronics encapsulants for thermal insulation.
HDK N20 is used in solar panel adhesives to improve UV resistance.
HDK N20 is incorporated into powder coatings for flow control.
HDK N20 is used in automotive coatings to enhance surface finish.
HDK N20 is used in anti-corrosion primers for barrier properties.
HDK N20 is added to cable gels to control viscosity.
HDK N20 is used in foam applications to prevent shrinkage.
HDK N20 is used in plastisols for rheological adjustment.
HDK N20 is added to medical silicone systems for uniform dispersion.
HDK N20 is used in polyurethane sealants for increased durability.
HDK N20 is used in printing plates to improve dimensional accuracy.
HDK N20 is applied in roof coatings for weather resistance.
HDK N20 is used in shoe sole materials for abrasion resistance.
HDK N20 is used in filament winding resins for better fiber wetting.
HDK N20 is incorporated into modeling clays for consistency.
HDK N20 is used in fiberglass laminates for matrix reinforcement.
HDK N20 is used in cable jointing kits for filling and sealing.
HDK N20 is used in fire-retardant compounds for improved char formation.
HDK N20 is used in friction materials to enhance wear resistance.
HDK N20 is used in sensor encapsulation for mechanical protection.
HDK N20 is applied in engine gaskets to improve sealing performance.
HDK N20 is used in electronic adhesives for improved gap filling.
HDK N20 is used in silicone foams for cell structure control.
HDK N20 is incorporated into ceramic slurries to control settling.
HDK N20 is used in dental resins for polishability and smoothness.
HDK N20 is added to LED potting compounds for thermal management.
HDK N20 is used in construction adhesives for high vertical hold.
HDK N20 is used in aerospace composites for lightweight strength.
HDK N20 is employed in UV-curable inks for precise rheological behavior.
Coatings & Inks:
Enhances viscosity, prevents pigment sedimentation, improves sag-resistance and rheology in diverse coating systems.
Adhesives & Printing:
Provides thixotropy and anti-sagging properties in adhesives, printing inks, and sealants.
Elastomers:
Acts as a reinforcing filler in silicone-based elastomers.
Cosmetics & Personal Care:
Functions as a thickener, absorbent, and texture enhancer in creams, lotions, sunscreens, and oral care products.
Powder Processing:
Used as a glidant and free-flow agent in technical powders.
DESCRIPTION
HDK N20 appears as an odorless, white, fluffy powder consisting of non-porous, chainlike silicon dioxide particles (~5–50 nm) that agglomerate into larger structures.
Its exceptionally high specific surface area (175–225 m²/g) enables formation of three-dimensional networks in liquid systems, imparting significant thixotropy and viscosity control
HDK N20 provides excellent reinforcing effects in elastomeric systems.
HDK N20 offers superior thixotropic behavior in solvent-based and water-based systems.
HDK N20 improves the mechanical, chemical, and thermal resistance of final formulations.
HDK N20 is compatible with a wide variety of resins and polymers.
HDK N20 can be used in combination with surface treatments for tailored properties.
HDK N20 complies with industrial standards for advanced performance fillers.
HDK N20 is a hydrophilic fumed silica produced by a flame hydrolysis process.
HDK N20 has a high surface area that contributes to excellent thickening properties.
HDK N20 appears as a white, amorphous powder with low bulk density.
HDK N20 consists of nano-sized silicon dioxide particles with high purity.
PROPERTIES
Property: Value
Primary Particle Size: 5–50 nm
Specific Surface Area (BET): 175–230 m²/g
Tapped Density: ≈ 40 g/L
pH (4% dispersion): 3.8–4.3
SiO₂ Content: > 99.8 %
Loss on Drying: (105 °C/2 h) < 1.5 %
Loss on Ignition: (1000 °C/2 h) < 2 %
Refractive Index: 1.46
Density (SiO₂): ~ 2.2 g/cm³
Appearance: White, fluffy colloidal powder
Solubility: Insoluble in water and solvents; chemically inert
Thermal Stability: Stable up to 1000 °C
Electrostatic Behavior: Tendency to accumulate static
Carcinogenicity: Not classified as carcinogenic
HANDLING & STORAGE
Handling:
Minimize dust formation; use local exhaust, dust masks, goggles, and gloves
Storage:
Keep in original sealed bags in a dry, cool, well-ventilated area.
Protect from moisture and volatile contaminants; marked “Best use before end” dates should be respected.
Packaging:
Available in 10 kg paper bags, 150 kg bulk bags, and silotruck quantities.
SAFETY & FIRST AID
Inhalation:
Dust may irritate respiratory tract—move to fresh air; seek medical help if irritation persists.
Skin:
Wash with soap and water; dryness or minor irritation may occur.
Eyes:
Rinse cautiously with water for at least 15 minutes; consult a physician if irritation continues.
Ingestion:
Rinse mouth; seek medical advice if large amounts ingested.
Commercial safety data sheets (SDS) are available;
HDK N20 is not known to be carcinogenic or mutagenic
