High-viscosity dimethyl silicone oils (generally referring to those with a viscosity of ≥10000 cSt, common specifications are 10000/50000/100000/300000 cSt, and ultra-high viscosity can reach more than 1,000,000 cSt) rely on their excellent viscosity-temperature property, high and low temperature resistance, lubricity, hydrophobicity, mold release property and chemical stability. With high viscosity, they also have stronger film adhesion, damping and buffering performance, and long-term lubrication and sealing effects. As core additives in the industrial, daily chemical, electronic and other fields, their core applications focus on scenarios requiring long-term lubrication, stable mold release, damping and buffering, and sealing protection. The following are the specific applications and technical key points by field, with typical viscosity selection references attached:
I. Mechanical Industry: Long-term Lubrication and Damping Buffering (Core Viscosity: 50,000 ~ 1,000,000 cSt)
This is the most important application field of high-viscosity dimethyl silicone oils. Their high-viscosity characteristics are utilized to achieve carbon-free and long-term lubrication resistant to high and low temperatures, adapting to the special needs of precision/high-temperature machinery.
- Precision machinery lubrication: Used for damping and lubrication of watch movements, optical instruments, precision bearings and micro gears to form a stable oil film, ensuring smooth operation and no wear of components (e.g., gear damping of high-end wristwatches, lubrication of microscope focusing mechanisms).
- High-temperature equipment lubrication: Adapted for motor bearings, transmission components of ovens/kilns, and high-temperature accessories around automobile engines. It can maintain lubrication performance in a wide temperature range of -50℃~200℃, replacing traditional mineral oils (to avoid high-temperature carbonization and coking).
- Dampers/buffers: Used in hydraulic dampers, furniture buffer hinges, automobile shock absorbers and damping components of instruments and meters. The viscous resistance of high viscosity controls the movement speed of components to achieve smooth buffering (e.g., slow-closing hinges for cabinet doors, damping for automobile seat adjustment).
- Metal processing mold release/rust prevention: High-viscosity silicone oil is formulated into a mold release agent for large rubber/plastic molds and metal die-casting molds. The film has strong adhesion, the workpiece surface is smooth after mold release, and it can also serve as short-term rust prevention for molds.
II. Rubber, Plastic and Molding Industry: High-end Mold Release and Product Modification (Core Viscosity: 10,000 ~ 500,000 cSt)
Compared with medium and low viscosity silicone oils, high-viscosity products form a denser and longer-lasting mold release film. After modification, they can improve the weather resistance and surface performance of rubber and plastic products without migration and without affecting subsequent bonding/printing (coupling agents are required for matching).
- High-end mold release: Suitable for mold release of large FRP products (wind turbine blades, yacht hulls), polyurethane foamed parts (insulation boards, automobile seats) and silicone products. A single spray can realize multiple mold releases, greatly improving production efficiency.
- Modification of rubber and plastic products: A small amount is added to plastics, rubbers and elastomers to improve the surface slip, scratch resistance and mold release property of products, while enhancing their high and low temperature resistance and aging resistance (e.g., high-end plastic pipes, silicone seals).
- Modification of hot melt adhesives/sealants: Added to hot melt adhesives and silicone sealants to adjust the system viscosity, improve the flexibility, hydrophobicity and weather resistance of the adhesive layer, and avoid cracking of the adhesive layer (e.g., building sealants, automotive hot melt adhesives).
III. Electronic and Electrical Industry: Sealing Protection, Insulation and Heat Dissipation (Core Viscosity: 50,000 ~ 300,000 cSt)
Utilizing the high insulation (volume resistivity ≥10¹⁴ Ω·cm), hydrophobicity and chemical inertness of high-viscosity dimethyl silicone oils, it adapts to the sealing, insulation and auxiliary heat dissipation needs of electronic components, with no corrosivity and no impact on circuit performance.
- Sealing/moistureproof of electronic components: Used for insulation and sealing of transformers, capacitors and high-voltage switchgear to form a dense hydrophobic film, prevent moisture intrusion, and improve the weather resistance and insulation stability of equipment.
- Precision electronic protection: Used for surface protection of camera modules, sensors and micro motors to avoid erosion by dust and water vapor, without affecting the heat dissipation and signal transmission of components.
- Base material of thermal conductive silicone oil: Served as the base carrier of high thermal conductive silicone oil (matching with thermal conductive fillers such as alumina and boron nitride) to make high thermal conductive silicone grease, which is used for heat dissipation of CPUs, LED lamp beads and power semiconductors. High viscosity ensures that the silicone grease does not run off or volatilize at high temperatures.
IV. Daily Chemical and Personal Care: Film-forming and Moisturizing for High-end Skin and Hair Care (Core Viscosity: 10,000 ~ 100,000 cSt, food grade/cosmetic grade)
Food grade/cosmetic grade high-viscosity dimethyl silicone oils (complying with USP/EP/Chinese Pharmacopoeia standards) have far better film-forming properties than medium and low viscosity silicone oils, realizing long-term water lock without stickiness, and are used in the core formulations of high-end skin care and hair care products.
- High-end skin care products: Added to creams, lotions and sunscreens to form a thin, breathable hydrophobic film on the skin surface, reduce water evaporation, achieve long-term moisturization, and improve the skin feel of products (smooth and non-sticky). It can also enhance the water and sweat resistance of sunscreens.
- Hair care products: Used in high-end conditioners, hair masks and essential oils, it adsorbs on the surface of hair cuticles, fills the gaps of cuticles, repairs dry and frizzy hair, and makes hair smooth and shiny. The film-forming property of high-viscosity silicone oil can make the hair care effect more durable (not easy to be washed off by water).
- Cosmetics: Used in liquid foundation, lipstick and mascara to improve the smoothness, water resistance and long-wearing effect of cosmetics, avoiding powder clumping and makeup fading.
V. Building Materials and Waterproofing: Hydrophobic Protection and System Modification (Core Viscosity: 100,000 ~ 500,000 cSt)
- Hydrophobic modification of building materials: Added to cement mortar, concrete and waterproof coatings to improve the hydrophobicity and impermeability of materials, prevent water intrusion, and enhance the freeze-thaw resistance and aging resistance of building materials (e.g., roof waterproof coatings, external wall insulation boards).
- Glass/stone protection: Formulated into a hydrophobic protective agent and sprayed on the surface of glass, marble and ceramic tiles to form a long-term hydrophobic film, achieving water proofing, stain resistance and easy cleaning (e.g., shower room glass, outdoor stone curtain walls).
VI. Other Special Fields
- Textile industry: Used for soft finishing of high-end textiles, especially chemical fiber and wool products, to improve the smoothness, drapability and wrinkle resistance of fabrics. The film-forming property of high-viscosity silicone oil can make the finishing effect more durable.
- Food industry (food grade): Used for mold release of food machinery (e.g., bread and pastry molds) and hydrophobic modification of food packaging materials, complying with food contact standards, with no peculiar smell and no migration.
- Aerospace: Used for lubrication and sealing of aerospace precision instruments and components around engines, adapting to an extreme temperature range of -60℃~250℃ to ensure the stability of equipment in harsh environments.
Core Selection Reference of High-viscosity Dimethyl Silicone Oils (by Scenario)
| Application Scenario | Typical Viscosity Specification (cSt) | Key Requirements |
|---|---|---|
| Precision machinery damping/watch lubrication | 500,000 ~ 1,000,000 | Low volatilization, high damping stability |
| Large mold release | 100,000 ~ 500,000 | Dense film formation, long-term mold release |
| Electronic insulation and sealing | 50,000 ~ 300,000 | High insulation, hydrophobicity |
| High-end skin and hair care | 10,000 ~ 100,000 (cosmetic grade) | Non-irritating, smooth skin feel, low volatilization |
| Damping hinges/buffers | 100,000 ~ 1,000,000 | Good viscosity-temperature property, no precipitation |
Key Usage Notes
- High-viscosity dimethyl silicone oil is a viscous paste/liquid at room temperature with poor fluidity. It can be properly heated (≤50℃) to reduce viscosity before use, or compounded with low-viscosity dimethyl silicone oil to adjust viscosity for convenient construction.
- When used for rubber and plastic modification and building material modification, if it is necessary to improve the bonding force between silicone oil and the substrate, silane coupling agents (e.g., KH550, KH560) should be matched to avoid migration and precipitation of silicone oil.
- Food grade/cosmetic grade high-viscosity dimethyl silicone oils must be selected for the food/daily chemical field, with compliant test reports (e.g., heavy metals, microorganisms, volatile organic compounds) provided.
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