Dihydroxyl-terminated Polydimethylsiloxane
(commonly known as 107 silicone rubber / hydroxyl silicone oil)
The lower the viscosity, the higher the fluidity and reaction activity with smaller molecular weight; the higher the viscosity, the better the film-forming property and elasticity with larger molecular weight. Below are the corresponding mainstream applications by viscosity range.
1. Low Viscosity (20–100 mPa·s, 25℃)
Characteristics: Small molecular weight, good fluidity, high hydroxyl content (usually 6%–12%), fast penetration, easy emulsification.
- Structuring control agent for silicone rubber: Most commonly used at 25–30 mPa·s; replaces diphenyldihydroxysilane, inhibits structuring of compounded rubber, improves processing fluidity and transparency, and eliminates heat treatment.
- Defoamer & foam inhibitor: Used in coatings, inks, daily chemicals and fermentation industries for rapid foam breaking and inhibition with good compatibility.
- Textile & leather finishing agent: Emulsion type, providing softness, smoothness, wrinkle resistance and water repellency, improving hand feel and wash resistance.
- Paper release & waterproofing: Light coating for label base paper and food packaging paper, offering anti-stick performance without affecting printability.
- Film-forming & lubricant for personal care: Applied in hair care, face cream and sunscreen products, delivering silky non-greasy feel and enhanced luster.
2. Medium Viscosity (100–5,000 mPa·s, 25℃)
Characteristics: Moderate fluidity, enhanced film-forming performance, balanced reaction activity, highest versatility.
- Base polymer for RTV silicone rubber: 500–5,000 mPa·s; used for one-component/two-component sealant, mold rubber and potting rubber, featuring good elasticity and strong adhesion after curing.
- Electronic & LED potting compound: 700–3,000 mPa·s; compounded with fumed silica and silica powder for insulation, moisture proofing, heat resistance and component protection.
- Insulating varnish & coating: 1,000–3,000 mPa·s; applied in electrical appliances, transformers and insulators, with temperature resistance (-50℃～250℃), insulation and moisture resistance.
- Mold release agent & anti-stick coating: 2,000–5,000 mPa·s; for metal casting, plastic and rubber molds, forming uniform film with smooth demolding and reusability.
- Modified polyurethane & epoxy resin: Reacts with isocyanate and epoxy groups to improve toughness, weather resistance and hydrophobicity, used in adhesives and coatings.
3. High Viscosity (5,000–100,000+ mPa·s, 25℃)
Characteristics: High molecular weight, viscous/semi-fluid state, excellent elasticity and mechanical properties, low hydroxyl content (0.01%–0.2%).
- High-strength silicone rubber & elastomer: 10,000–50,000 mPa·s; used in building sealant, structural adhesive and automotive seals, featuring high elongation, aging resistance and weather resistance.
- Thick-layer potting & sealing: 20,000–100,000 mPa·s; for high-power power supplies, high-voltage modules and automotive electronics, providing shock absorption, insulation and waterproofing after curing.
- Damping & shock-absorbing materials: Above 50,000 mPa·s; applied in precision instruments, automotive shock absorption and audio damping, with stable damping performance and noise reduction in wide temperature range.
- Waterproof & anti-corrosion coating: 30,000–80,000 mPa·s; for concrete, steel structure and pipelines, enabling thick film coating with acid and alkali resistance, weather resistance and long-term waterproof performance.
Viscosity – Application Quick Reference Table
| Viscosity (mPa·s) | Typical Applications | Core Advantages |
|---|---|---|
| 20–100 | Structuring control agent, defoamer, textile finishing | High activity, strong permeability, easy emulsification |
| 100–5,000 | RTV base polymer, electronic potting, insulating varnish | Balanced fluidity & film-forming, high versatility |
| 5,000–100,000+ | High-strength elastomer, damping material, thick-layer sealing | High elasticity, superior mechanical property, aging resistance |
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