Organosilicone emulsions are primarily used as silicone oil fabric softening finishing agents. The first generation of organosilicone fabric finishers consists of mechanical mixtures of dimethyl silicone oil and hydrogen-containing silicone oil (and their derivatives). The second generation is hydroxyl-terminated polydimethylsiloxane emulsion, which is produced through emulsion polymerization under specific conditions using octamethylcyclotetrasiloxane monomer, water, emulsifier, catalyst, and other raw materials.


Since polymerization and emulsification occur in a single step, this method offers advantages such as short processing time, high efficiency, simple equipment, and convenient operation. Moreover, the resulting emulsion is highly stable with extremely uniform particle size. The polymer obtained has reactive groups (hydroxyl) at both ends, enabling further film formation reactions, thereby enhancing application performance—an advantage that mechanically emulsified silicone oils cannot match.


Types of Organosilicone Emulsions


Hydroxyl silicone oil emulsions can be classified into several types—cationic, anionic, nonionic, and mixed ionic—depending on the surfactants used.


1. Cationic Hydroxyl Silicone Oil Emulsion  
Cationic hydroxyl emulsions typically use quaternary ammonium salts (such as cetyltrimethylammonium chloride, as reported in foreign literature) as emulsifiers and ammonium hydroxide as catalysts. This type of emulsion is suitable for post-finishing of various textiles, improving fabric hand feel, elasticity, smoothness, and crispness. Another unique advantage is its excellent performance as a waterproofing agent. When combined with methyl hydrogen-containing silicone oil emulsion, it achieves high levels of waterproofing effectiveness and durability. It is widely used as a waterproofing agent for vinyl fiber tarpaulins and polyester-cotton fabrics.


2. Anionic Hydroxyl Silicone Oil Emulsion  
Anionic hydroxyl emulsions are characterized by good compatibility with other textile finishing agents and exceptional emulsion stability. Since most auxiliaries used in textile printing and dyeing are anionic, cationic hydroxyl emulsions often lead to emulsion breakdown and oil separation. In contrast, anionic emulsions avoid these issues, making them more popular among users and widely applied.


3. Mixed Ionic Hydroxyl Silicone Oil Emulsion  
Although cationic hydroxyl emulsions are excellent fabric softeners, they are sensitive to hard water and cannot be used together with 2D resin (dihydroxymethyl dihydroxyethylene urea), magnesium chloride catalyst, or anionic optical brighteners in the same bath, thus limiting their applications. Additionally, due to poor emulsion stability, the organosilicone polymer tends to separate from the emulsion and float on the surface—a phenomenon known as "oil floating." However, if a combination of cationic and nonionic emulsifiers is used during emulsion polymerization, the drawbacks of cationic emulsifiers can be overcome. The resulting organosilicone emulsion becomes resistant to hard water, compatible with 2D resin, magnesium chloride, and optical brightener VBL, and exhibits excellent heat and freeze resistance.


4. Nonionic Hydroxyl Silicone Oil Emulsion  
Nonionic hydroxyl emulsions offer greater adaptability and improved stability compared to ionic types, prompting extensive research worldwide. For example, UltrateX FSA, a new product developed by Ciba-Geigy of Switzerland, is a nonionic emulsion of hydroxyl-terminated polydimethylsiloxane with a molecular weight exceeding 200,000, representing a significant advancement over the anionic DC-1111 emulsion produced by Dow Corning in the United States.


5. Organosilicone Finishing Agents with Other Reactive Groups  
To meet the demands of advanced textile finishing and improve oil resistance, anti-static properties, and hydrophilicity of silicone-finished fabrics, researchers have introduced additional functional groups—such as amino, amide, ester, cyano, carboxyl, and epoxy groups—into organosilicone molecules. These modifications endow organosilicone finishing agents with special effects. For instance, incorporating amino groups into the silicone molecule makes it particularly effective for shrinkage prevention and softening of woolen fabrics. Introducing amide groups is suitable for anti-soiling finishing and significantly improves softness; introducing cyano groups enhances oil resistance; copolymers of poly(ethylene oxide) ether and silicone exhibit excellent antistatic effects; fluorine-modified silicones offer numerous advantages including oil repellency, stain resistance, antistatic properties, and water repellency.