1、 Molecular Structure and Chemical Essence
The chemical name of Ethyl Siloxane Fluid is polydiethylsiloxane, and its molecular formula can be expressed as C ₄ₙ₊₁₂ H ∝₀₊₁₀ₙ Si ₙ₊₂ O ₙ₊₁, CAS number 63148-61-8. Its core structure consists of a silicon oxygen bond (Si-O) main chain and an ethyl (- C ₂ H ₅) side chain. This unique molecular design endows it with both the high stability of inorganic silicon oxygen bonds and the flexibility of organic ethyl. Physically, ethyl silicone oil appears as a colorless to light yellow transparent liquid with a density range of 0.95-1.05g/cm ³, a melting point below -70 ℃, a flash point exceeding 265 ℃ (open cup), and a working temperature range covering -60 ℃ to 150 ℃, demonstrating excellent temperature resistance.
2、 Industrial preparation: precise control from raw materials to finished products
The industrial production of ethyl silicone oil mainly adopts the chloroethane metal magnesium Grignard reagent method:
Preparation of Grignard reagent: Metal magnesium shavings are reacted with chloroethane in toluene solvent to generate ethyl Grignard reagent (C ₂ H ₅ MgCl). This step requires strict control of the reaction temperature between 50-80 ℃ to avoid side reactions.
Silanization reaction: Ethyl orthosilicate (Si (OC ₂ H ₅) ₄) is added dropwise to the system, and a mixture of diethyldiethoxysilane (C ₂ H ₅) ₂ Si (OC ₂ H ₅) ₂ and triethylethoxysilane (C ₂ H ₅) ∝ SiOC ₂ H ₅) can be directionally synthesized by controlling the molar ratio of Si (OC ₂ H ₅) ₄ to chloroethane.
Hydrolysis polycondensation: under the catalysis of hydrochloric acid, the silane mixture is hydrolyzed at 45 ℃ for 4-5 hours to produce oligomeric diethylsiloxane ((C ₂ H ≮) ₂ SiO) ₙ). During the hydrolysis process, the pH value needs to be accurately controlled at 3-5 to avoid gel.
Molecular rearrangement: Use concentrated sulfuric acid (5-8% of the crude product mass) to catalyze rearrangement at 75-80 ℃, adjust the molecular weight distribution through equilibrium reaction, and finally extract different viscosity fractions through vacuum distillation (0.133-0.40kPa).
The key control points of this process include:
The fluctuation of reaction temperature should be controlled within ± 2 ℃
The catalyst dosage needs to be precise to the 0.1% level
The top temperature of the distillation tower needs to be stable at the boiling point of the target fraction ± 1 ℃
3、 Performance advantage: Multi dimensional analysis of its application value
Lubrication performance: The low surface tension (20-25mN/m) and low viscosity coefficient (0.01-0.1mm ²/s) of ethyl silicone oil make it an ideal choice for precision mechanical lubrication. In the aerospace field, its volatility is 90% lower than mineral oil, ensuring that satellite gyroscopes can operate continuously and stably in extreme environments ranging from -70 ℃ to 150 ℃.
Dielectric properties: The volume resistivity reaches 1 × 10 ¹⁵Ω· cm, the dielectric constant is 2.5-3.0 (1kHz), and the breakdown field strength is 15-20kV/mm, making it an alternative solution for insulation oil in high-voltage transformers.
Chemical stability: It can withstand strong corrosive media such as concentrated sulfuric acid and sodium hydroxide, and does not undergo hydrolysis within the pH range of 2-12. In the field of medical devices, its biocompatibility meets the ISO 10993 standard and has been widely used in catheter lubrication and implantable device packaging.
Environmental adaptability: It maintains fluidity at a low temperature of -60 ℃ and has a volatilization loss rate of less than 0.5%/h at a high temperature of 150 ℃, making it a core material for lubrication of Arctic scientific research equipment and dust-proof coating of desert photovoltaic modules.
4、 Application area: Full industry chain coverage from industry to people's livelihood
Industrial manufacturing:
Release agent: In the production of automotive tires, ethyl silicone oil can reduce the release force by 40% and extend the service life of the mold by three times.
Hydraulic oil: In the hydraulic system of CNC machine tools, its shear stability reduces system pressure fluctuations to ± 0.5 bar.
Sealing agent: In the sealing of wind turbine gearboxes, it can withstand alternating temperatures from -40 ℃ to 120 ℃, with a sealing life of more than 10 years.
Electronic and Electrical:
Insulation material: In 5G base station filters, the dielectric loss tangent (tan δ) is as low as 0.0002, reducing signal attenuation by 30%.
Heat dissipation material: In data center servers, the thermal conductivity reaches 0.6W/(m · K), which is 50% higher than traditional silicone grease.
In the field of cosmetics:
Skin care matrix: In high-end face cream, its film-forming property can reduce the skin water diversion loss rate by 60% while maintaining air permeability.
Make up setting: add 2-5% ethyl silicone oil in liquid foundation, which can extend the makeup holding time to more than 12 hours.
In the field of medicine:
Drug carrier: In transdermal drug delivery systems, its permeation enhancing effect can increase drug absorption by 3-5 times.
Medical equipment: In disposable infusion sets, its lubricity can reduce intubation resistance by 70% and reduce patient pain.
5、 Market pattern and development trend
The global market size of ethyl silicone oil has exceeded 2 billion US dollars, with China occupying 35% of the market share. The main production enterprises include Xinyuan Chemical (Shandong), Zhejiang Runhe, Jiangxi Baite, etc. Among them, Xinyuan Chemical has achieved a breakthrough in annual production capacity of 50000 tons of ethyl silicone oil through a full industry chain layout (from trifluoropropene to fluorosilicone rubber).
The future development direction presents three major trends:
High performance: Develop specialized silicone oils that are resistant to ultra-low temperatures (-100 ℃) and ultra-high temperatures (300 ℃) through molecular design.
Functionalization: Introducing hydrogen containing groups to prepare ethyl hydrogen containing silicone oil for crosslinking and curing systems.
Greening: Using biobased chloroethane instead of petroleum based raw materials to reduce carbon footprint by more than 30%.
6、 Technical challenges and breakthrough directions
The current industry is facing two major technological bottlenecks:
Molecular weight control: Traditional sulfuric acid catalytic method can easily lead to a wide molecular weight distribution (PDI>2.0), which affects product consistency. The solid acid catalyst developed by Xinyuan Chemical can reduce PDI to below 1.3.
Environmental substitution: Traditional processes produce sulfuric acid containing waste liquid (pH<1), which has high treatment costs. The ionic liquid catalytic system developed by Zhejiang University can achieve waste liquid recycling with a cost reduction of 40%.
7、 Conclusion
From the exquisite design of molecular structure to the wide coverage of industrial applications, ethyl silicone oil has become an indispensable "industrial monosodium glutamate" in modern industry. With the breakthrough of new material technology, its potential in emerging fields such as new energy and biomedicine is gradually being released. In the future, through collaborative innovation between industry, academia, and research, ethyl silicone oil is expected to achieve new breakthroughs on the path of sustainable development.
