Preparation of Polyether-Modified Polysiloxane Defoamers

Ordinary polysiloxane defoamers, due to their low surface energy and strong hydrophobicity, exhibit poor miscibility with other organic substances, leading to particularly ineffective performance in aqueous systems. For instance, under high-shear and high-temperature conditions—such as those encountered in jet dyeing processes—conventional polysiloxane defoamers tend to form film-like precipitates, which can cause spotting on dyed fabrics. In contrast, polyether-modified polysiloxanes, thanks to the incorporation of hydrophilic polyether segments, can disperse and emulsify effectively in water while maintaining excellent emulsion stability. Additionally, these polymers possess inverse solubility properties, making them ideal for high-temperature, high-pressure liquid-flow dyeing processes. As a result, polyether-modified polysiloxanes have increasingly gained attention in recent years for their applications in defoaming agents. In this experiment, we used highly hydrogenated silicone oil as the raw material and synthesized low-hydrogenated silicone oil via a controlled polymerization method. Meanwhile, propargyl alcohol was employed as the initiator, and NaOH served as the catalyst to carry out ring-opening copolymerization of ethylene oxide and propylene oxide, yielding an allyl-terminated polyoxyalkylene ether. Finally, this allyl-terminated polyoxyalkylene ether was grafted onto the low-hydrogenated silicone oil, resulting in the production of the desired polyether-modified polysiloxane, which was then formulated into a defoaming agent.

2021-11-12

An Analysis of Knowledge on Silicone Oil and Low-Hydrogen Silicone Oil

Silicone oil is a type of polyorganosiloxane with chain-like structures of varying degrees of polymerization. It is produced by hydrolyzing dimethyldichlorosilane with water to form initial oligomeric cyclic compounds. These cyclics are then cracked and purified through distillation to yield low-molecular-weight cyclic intermediates. Finally, by combining these cyclic compounds with end-capping agents and a catalyst, a mixture with tailored degrees of polymerization is obtained. The resulting mixture is further refined via vacuum distillation to remove low-boiling byproducts, ultimately yielding pure silicone oil.

2021-11-12

Dimethyldiethoxysilane becomes key to silicone resin production.

China's development of organosilicon glass resins and high-temperature mica binders was spearheaded by Huo Changshun, Chen Rufeng, and others from the Chenguang Chemical Research Institute under the Ministry of Chemical Industry. In the late 1970s, they successfully pioneered the synthesis of CTS-103 organosilicon resin—commonly known as "organosilicon glass resin"—using a hydrolysis-condensation reaction of methyltriethoxysilane catalyzed by an acidic catalyst. Initially, this resin found applications in advanced paper treatment and protective coatings for metal surfaces. It also proved highly effective in bonding mica sheets or mica powders. In 1980, Fang Sanhua, Xue Zhiqing, and Li Yansheng at the Shanghai Resin Factory independently adopted solid-state cation exchange resins as temporary acidic catalysts. Specifically, Fang Sanhua used pure methyltriethoxysilane, while Xue Zhiqing and Li Yansheng incorporated small amounts of dimethyldiethoxysilane alongside methyltriethoxysilane to synthesize two transparent, wear-resistant silicon resins named SAR-1 and SAR-2, respectively. Notably, these resins exhibited exceptional storage stability due to the absence of residual inorganic acids—so much so that no sign of gelation was observed even after one year. Moreover, the introduction of a minor amount of difunctional raw material into SAR-2 resulted in a product that balanced hardness with flexibility, broadening its range of applications. Today, these resins are widely used across various materials, including glass, plastics, and metals. They are particularly well-suited for protecting transparent plastics such as polycarbonate, polystyrene, and PVC, as well as serving as moisture-proof and insulating coatings for electronic components. As a result, large-scale production of these innovative materials has rapidly taken hold.

2021-11-12

Applications and Properties of Dimethyldiethoxysilane

This product serves as a structure control agent in the preparation of silicone rubber, a chain extender in the synthesis of organosilicon products, and a raw material for silicone oil production.

2021-11-09

Unveiling the Mysteries of Dimethyldiethoxysilane

Dimethyldiethoxysilane, with the molecular formula (CH3)2Si(C2H5O)2, is a colorless, transparent liquid. It is primarily used as a structure-control agent in the production of silicone rubber, as a chain-extending agent in the synthesis of organosilicon products, and as a raw material for silicone oil production. Inhalation of its vapor or mist can irritate the eyes, mucous membranes, and upper respiratory tract, while direct skin contact may cause irritation. Prolonged exposure can lead to symptoms such as nausea, dizziness, headaches, and gastrointestinal disturbances. The substance is highly flammable and can ignite when exposed to high heat, open flames, or strong oxidizing agents.

2021-11-09