The Properties of Amino Silicone Oil

Nov 20, 2020

1 Classification of amino silicone oil Amino silicone oil can be divided into single-end type, double-end type, side-end type, copolymer type and mixed type according to the position of the amino group in the polysiloxane molecule. Classified by end groups, there are amino silicone oils such as methyl, methoxy and hydroxyl. The end group is methyl called "inactive amino silicone oil", which is more suitable for processing cotton and silk fabrics. The end groups are hydroxyl and methoxy group called "active amino silicone oil", suitable for processing animal fibers. Classified by amino groups, there are primary amino groups (-NH2), secondary amino groups (-NHCH3), tertiary amino groups [-N(C2H5)2], and primary and secondary amino groups (-NHCH2CH2NH2).

2 The soft mechanism of amino silicone oil The excellent flexibility of amino silicone oil comes from its basic geometric molecular configuration. The main chain of polysiloxane is a twisted spiral linear structure, which is composed of silicon atoms and oxygen atoms. Composition, the energy required to rotate around the -Si-O- bond is almost zero, which shows that the rotation of -Si-O- is free and can rotate 360°, which makes the main chain very flexible. There are  2  methyl groups on each silicon atom of polydimethylsiloxane, and these  2  methyl groups are on the plane perpendicular to the connecting line of  2 similar oxygen atoms. The amino group in the amino silicone oil has strong polarity, interacts with the hydroxyl and carboxyl groups on the surface of the fiber, and is very firmly oriented and adsorbed on the fiber. The -Si-O- bond main chain and the methyl group and polydimethyl group on the silicon atom Like siloxane, the coefficient of static friction between the fibers is reduced, and a slight force can make the fibers slide, thus feeling soft and smooth.

3 Characterization of amino silicone oil Amino silicone oil is usually characterized by three characteristic parameters: ammonia value, viscosity, and reactivity. These three characteristic parameters basically reflect the quality of amino silicone oil and affect the performance of the fabric after treatment.

3.1  Ammonia value The various properties (such as soft hand feel, smoothness, elasticity, etc.) imparted to fabric by amino silicone oil are all caused by the amino groups in the polymer. The ammonia value is proportional to the amino content (percentage) in the amino silicone oil. The higher the amino content, the greater the ammonia value, and the softer and smoother the finished fabric will feel. The ammonia value of the amino silicone oil used as fabric softener is generally  0.2 ～0.6 between. Although the softness of amino silicone softener is related to the ammonia value. However, the properties of fabrics do not completely depend on the ammonia value. Whether the amino group is evenly distributed or not, the molecular weight of the amino silicone oil will affect the properties of the fabric.

3.2 Viscosity The viscosity of amino silicone oil is directly proportional to the molecular weight. The larger the molecular weight, the better the film-forming properties of amino silicone oil on the fabric and the softer the handle. However, because the amino silicone oil molecules are cross-linked when the fabric is dried, the initial molecular weight of the amino silicone oil is different from the molecular weight of the final film formed on the fabric. If the viscosity is too low, the treated fabric cannot obtain sufficient smoothness, but if the viscosity is too high, it is difficult to make microemulsion. The viscosity of amino silicone oil used as fabric finishing agent is generally about 1000mPa·s , and some are as high as  10000mPa·s .