Non-ionic softener 
Non-ionic softeners are generally polyoxyethylene esters (or ethers) of fatty acids (or alcohols), pentaerythritol or sorbitol fatty esters. Due to the poorer adsorption of non-ionic softeners on fibers compared to ionic softeners, they can only provide a smoothing effect. However, they can be used in combination with ionic softeners, are compatible with other substances, have good stability against electrolytes, and do not cause fabric yellowing. They can be used as a non-durable softening agent for fabrics or as an important component of synthetic fiber spinning oil. Some of their products can be used as imitation silk finishing agents for fabric "silk-like sound". 
Cationic softener 
There are many types of such softeners, and they are currently the most commonly used softeners. 
The main reason is that most fibers carry negative charges in water, and cationic softeners can easily adsorb onto the surface of the fibers, with strong binding ability. They can withstand high temperatures and washing, and after treatment, the fabric becomes plump and smooth, improving the fabric's wear resistance and tear strength. They also have a certain anti-static effect on synthetic fibers. Therefore, they are widely used in cotton, nylon, acrylic, and other fabrics. There is also a type of this product suitable for silk. However, some cationic softeners are prone to yellowing at high temperatures and accompanied by a decrease in light fastness. Cationic softeners are generally derivatives of octadecylamine or dimethyl octadecylamine or condensates of stearic acid and polyethylene polyamine. According to their structure, they can be classified as tertiary amine softeners, quaternary ammonium salt softeners, imidazoline quaternary ammonium salt softeners, and dialkyl dimethyl quaternary ammonium salt softeners, etc. 
Gender-neutral softener 
The amphoteric softener is a type of softener developed to improve the performance of cationic softeners. It has a stronger affinity for synthetic fibers and does not have the drawbacks such as yellowing or color change of dyes. It can also be used in the re-washing process of silk to make the silk feel better. The amphoteric softener can also be used together with cationic softeners to achieve a synergistic effect. These softeners generally have an alkylamine lactone structure. 
Organic silicone softener 
These softeners are emulsions or microemulsions of poly siloxanes and their derivatives, which can give fabrics a good soft and smooth feel. The products are produced through processes such as emulsion polymerization, emulsification of polymer silicon oil, and modification and compounding. A complete system has been basically established, and there are also many varieties and brands available for supply. However, the application effects and performance still vary greatly. 
2-Methylsilicone emulsion: 
This is the earliest product applied in organic silicon softeners. The silicone oil used as a softener generally has a relative molecular weight of 60,000 to 70,000. After processing, it can give the fabric a smooth, firm and refreshing feel, reduce the friction coefficient of the fabric, and improve the wear resistance and seamability of the fabric. However, because there are no reactive groups on its molecular chain, it cannot react with fibers, nor can it cross-link itself. Instead, it merely adheres to the surface of the fibers through molecular attraction. Therefore, its washability is poor, and the improvement in elasticity is also limited. 
2. Organic Siloxane Hydroxy Emulsion (Hydroxy Silica Oil Emulsion): 
This was the most widely used organic silicon-based softener in our country during the 1980s. Its relative molecular mass generally ranges from 60,000 to 80,000. The larger the relative molecular mass, the better the softness and smoothness. Due to the terminal and end groups of its molecular chain, it can react with the reactive groups on the fibers or itself under the action of crosslinking agents and catalysts to form a certain elastic polymer film. Therefore, it has washability and can improve the elasticity of the fabric. Organic silicon hydroxy emulsions are classified into cationic organic silicon hydroxy emulsions and anionic organic silicon hydroxy emulsions according to the different ionic nature of the emulsifying agents used. Although the hydroxyl groups at the terminal of the molecular chain help to improve its hydrophilicity and emulsion stability, the difficulty in controlling the fine and uniform size of the emulsion particles of organic silicon hydroxy emulsions makes it difficult to control the stability of the emulsion. During application, it is prone to the phenomenon of oil floating, causing oil stains that are difficult to remove on the fabric. Therefore, the stability of the emulsion of organic silicon hydroxy softeners is also an important indicator for evaluating their quality. 
3. Hydrophilic soluble organic silicon (polyether type hydrophilic organic silicon): 
These organic silicon softeners are usually polyether and epoxy-modified polysiloxanes. They appear as colorless and transparent thick liquids and can provide fabrics with excellent moisture absorption, breathability, and anti-static properties. Due to their non-ionic nature, they can be mixed with various additives for application. When used together with resins, they can reduce the chlorine absorption and formaldehyde release of the resins. Besides being used for resin finishing and softening finishing, they are also widely used in coating and dyeing processes. They not only improve the hand feel of fabrics affected by adhesives but also overcome the shortcomings of adhesives sticking to rollers. 
4. Amino-modified organosilicon: 
Introducing amino groups onto the macromolecular chains of polysiloxanes can significantly improve the properties of organic silicon. The introduction of amino groups not only forms a strong orientation and adsorption effect with fibers, reducing the friction coefficient between fibers, but also can undergo chemical reactions with epoxy groups, carboxyl groups, and hydroxyl groups. Therefore, it is applicable to various fibers such as cotton, wool, silk, viscose fibers, polyester, nylon, and acrylic fibers, as well as their blended fabrics. After the fabric is finished with this treatment, it can achieve excellent softness and resilience, with a soft and full feel, smooth and delicate texture. Generally speaking, the higher the amino content, the better the softness. However, a higher amino content also means greater yellowing. 
This is mainly because there are two amino groups (primary and secondary amine groups) on the side chain of —(CH2)NH(CH2)2NH2, with a total of three reactive hydrogen atoms, which are prone to oxidation to form chromophores. Moreover, this dual amino structure has a synergistic effect in accelerating oxidation. Therefore, there must be an optimal balance between the amino content and the yellowing property. Amine-modified organosilicon was transformed into microemulsions, and it has developed rapidly in the past decade. Due to the introduction of amino groups on the siloxane molecule, its hydrophilicity is enhanced. Thus, by selecting appropriate emulsifiers and preparation methods, it can be made into microemulsions with particle diameters below 0.15 μm. 
Due to its particle size being smaller than the wavelength of visible light and having no impedance to visible light, it can make the emulsion transparent. The reason is that the particle size of its particles is only 1/10 of that in ordinary emulsions, which increases the number of effective particles in the microemulsion by 10^3 times (assuming the concentration is the same). The contact opportunities between the microemulsion and the fabric are greatly increased, and it has good spreading properties on the fabric surface, easily penetrating into the fiber interior. Therefore, this product can give the fabric good internal softness, and this softness is also more durable. The water solubility, storage stability, heat resistance stability, and shear stability of the microemulsion products are generally also better. 
The commonly used dual-amino organosilicon softeners have excellent softening effects, but they have poor whiteness, water absorption, and stain removal properties, and these drawbacks become more severe as the number of amino functional groups in the polymer increases. To improve these shortcomings, changes in the type and quantity of amino functional groups can be achieved. Altering the type of amino functional groups mainly involves converting primary amine groups into secondary or tertiary amine groups. For example, organic silicon softeners modified with N-propyl cyclohexylamine (secondary amine) and N-propyl piperazine (tertiary amine) have been developed for fabric finishing. These softeners can reduce yellowing during baking and have less hydrophobicity compared to organic silicon softeners with primary amine groups, but they give the fabric a slightly dry feel. They are mainly used for softening the finishing of bleached fabrics and light-colored fabrics. 
Furthermore, in order to achieve a highly smooth texture, the two ends of the large molecules of dimethylsiloxane are modified with amino groups for sealing. These modified molecules can form a very orderly and directional arrangement on the fabric, thereby providing an excellent smooth feel. If the part side chains and both ends of the polysiloxane are all modified with amino groups and used as a fabric finishing agent, it can make the fabric have better softness. Currently, the development of organic silicon softeners is very rapid, with an increasing variety and a decrease in price. The application quantity of organic silicon softeners has increased significantly. Besides the various types of organic silicon softeners mentioned above, there are also epoxy group modified, amide group modified, carboxyl group modified and other organic silicon softeners. Due to the limited availability at present, they will not be introduced one by one here. 
Low-molecular-weight polyethylene emulsion 
This type of softener is a product formed by oxidizing low-molecular-weight polyethylene and then emulsifying it. It has a certain affinity for fibers, giving the fabric a smooth feel. It can be used in the same bath as resins and can enhance the tear strength and wear resistance reduced by resin treatment. It is a cheap fabric softening and smoothening aid that can be used before the popularization of organic silicon softeners. Currently, this type of softener is generally not used alone. It can be used as a component of various softeners for compounding, or as a stabilizer in hydroxyl silicone emulsions.