The main factors related to the physical properties of silicone oil finishing agents and the softness of wool include: the molecular structure of silicone oil, hydrophilicity, and its adsorption capacity on fibers.
The molecular structure of silicone oil has a great influence on its interaction with fibers. For example, ternary copolymer silicone oil (synthesized from amino-terminated polyether and epoxy-terminated polyether silicone oil) has good physical and chemical stability and can significantly improve the feel of cashmere knitted fabrics. In addition, polyurethane-modified silicone oil not only improves the softness of the silicone oil, but also enhances the elasticity and anti-wrinkle properties of the fabric by introducing elastic segments of polyurethane.
The hydrophilicity of silicone oil is also an important factor affecting its effect on wool softness. Silicone oil with better hydrophilicity can be better dispersed in water, thereby penetrating into the fiber more effectively and improving the feel and appearance of the fiber. For example, hydrophilic block silicone oil finishing agent can give fabrics good hydrophilic and soft properties at the same time.

Adsorption capacity
The adsorption capacity of silicone oil determines whether it can effectively adhere to the fiber, thereby changing the physical state of the fiber. Highly absorbent silicone oil can better cover the fiber surface and reduce friction between fibers, thereby improving the softness and smoothness of the fiber. For example, aminosilicone oil is widely used in the finishing of fiber fabrics due to its good adsorption properties.

To sum up, the physical properties related to wool softness in silicone oil finishing agents mainly include the design of its molecular structure, optimization of hydrophilicity and good adsorption capacity. These properties work together to effectively improve the feel and appearance of wool fabrics, making them softer and more comfortable.