Soft finishing is a process that makes up for the stiffness and roughness of the fiber material during the dyeing and finishing process, so as to make the fiber material feel soft. Alfa Chemistry offers a range of chemical softeners including but not limited to anionic, cationic, amphoteric, nonionic and silicone softeners.
Classification
Softening methods include mechanical softening and chemical softening. Among them, the chemical softening finishing method uses the effect of softener to reduce the friction coefficient between fibers to obtain a softening effect. According to the ionic type, softeners can be divided into anionic, cationic, amphoteric and nonionic. According to the chemical composition of the softener, it can be divided into non-surface active, surfactant, reactive and polymer emulsion type. Here are a few typical softeners:
- Anionic Softener
Anionic softeners are usually sulfate or sulfonate compounds, and typical components include anionic compounds with long-chain alkanes such as sodium stearyl succinate sulfonate and octadecyl ester sulfate. They generally have good wettability and thermal stability. - Nonionic Softener
Typical representatives of nonionic softeners include fatty acid polyol esters (such as pentaerythritol fatty acid esters, glycerol monofatty acid esters and sorbitan fatty acid esters), fatty acid diethanolamides, alkanolamides and polyoxyethylene fatty acid amides, etc. - Cationic Softener
Compared with anionic and non-ionic types, cationic softeners have strong binding ability to various fibers. This is mainly due to the fact that most fibers are negatively charged in water, and cationic softeners are easily adsorbed on the fiber surface. According to the structure, they can be divided into tertiary amine softener, quaternary ammonium salt softener, imidazoline quaternary ammonium salt softener, dialkyldimethyl quaternary ammonium salt softener, etc.
Diethyl ester dimethyl ammonium chloride
- Amphoteric Softener
Amphoteric softeners are a class of softeners developed to improve cationic softeners. They have a strong affinity for synthetic fibers, and overcome the disadvantages such as yellowing and discoloration of dyes. Such softeners are generally of the alkylamine lactone type structure. - Silicone Softener
Such softeners are emulsions or microemulsions of polysiloxanes and their derivatives. Typical products include dimethyl silicone oil emulsion, hydroxy silicone oil emulsion, polyether-type hydrophilic silicone, amino-modified silicone, and silicone softeners with epoxy-modified, amide-modified, and carboxyl-modified.
General structures of amino functional silicones. [1]
- Polymer Emulsion
This type of softener is mainly an emulsion made of polymers such as polyethylene and silicone resin. - Non-Surfactant Softener
Natural oils (stearic acid, coconut oil, white oil), paraffins, amine salts of fatty acids.
Soft Finishing Mechanism
- Reduce the surface tension of fibers: Since the softener is prone to directional adsorption on the interface (textile fiber and finishing liquid), the interfacial tension of the fiber is reduced, the work required to expand the surface area is reduced, and the fiber becomes easy to expand the surface and stretch its length.
- Reduce the coefficient of friction of fibers: The surfactant is adsorbed in a thin layer on the fiber surface, and the hydrophobic groups are arranged neatly outwards. In this way, friction occurs between hydrophobic groups that slide against each other, and the longer the hydrophobic group, the easier it is to slide.
Reference
- Mohammad Mahdi Abolhasani, et al. Polymer Bulletin, 2020, 77, 2557–2572.
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