Introduction
In order to make the fabric have a soft, smooth or plump feel, in addition to mechanical finishing, most Fabrics must be finished with softeners. This article introduces the functions, requirements, types and characteristics of softeners.
1. The function of softener
1. Replenish the natural oils lost by natural fibers during refining, bleaching and other processes to make the hand feel better. ideal.
2. Attached to natural fibers or synthetic fibers to improve smoothness and strength and improve hand feel.
3. Improve the wearing performance of fabrics through certain properties of softeners.
In order to achieve the above functions, softeners are generally substances with the smoothness and feel of grease. When attached to the surface of fibers, they can reduce the frictional resistance between fibers and make the fibers lubricated and soft. There are also some softeners that can cross-link with some reactive groups on the fiber to achieve the purpose of washing resistance.
2. Requirements for softeners
1. The working fluid must be very stable under various softening processing conditions.
2. Does not reduce the whiteness and dye fastness of fibers or fabrics.
3. The fibers or fabrics that have been softened are not easily discolored by heat, and there should be no changes in color, feel, or smell during storage. 4. If the softener is an emulsion, its emulsion stability should be better. 5. According to different processing requirements, it can have appropriate water absorption, water repellency, anti-static and other properties (should be selected according to different requirements of the fabric). Resistant to washing or dry cleaning. 6. No adverse effects after contact with human skin.
Due to the wide variety of textiles, the use of different fibers, different fabric specifications, different fabric uses, and different finishing requirements, the selection of softeners cannot be generalized. The selection should be based on the softening mechanism and function of various softeners. Softener that meets the requirements. In addition, the performance of each softener is always limited. To obtain good results with multiple properties, you can use two or more softeners in combination (or compound them into a new softener product) ). For example, the combined application of silicone softeners and long-chain aliphatic softeners can achieve better effects of soft, plump, and smooth hand feel. The application of softeners can also be combined with mechanical softening and finishing, often achieving good results. Effect.
3. Types of softeners
Softeners are the type of auxiliaries with the largest variety and the largest dosage among dyeing and finishing auxiliaries. According to reports, among the 920 domestic and foreign auxiliary samples collected by the Shanghai Printing and Dyeing Technology Research Institute from 1990 to 1999, 350 were softeners, accounting for 38%. There are so many varieties of softeners. According to their chemical structures, they are basically two categories: long-chain aliphatic or high-molecular polymer. The long hydrocarbon chains in the molecular structure of long-chain aliphatic softeners can be randomly arranged in a curled state, forming the flexibility of the molecules. Their flexible molecules are adsorbed on the fiber surface to lubricate the fiber and reduce the friction between the fiber and the fiber. The dynamic and static friction coefficients of fibers.
Therefore, long-chain aliphatic structures generally have better softening effects. Among softeners, there are not only many varieties, but also larger dosages. This type of softener can be divided into anionic, cationic, nonionic and amphoteric according to its ionicity. In addition, natural oils and paraffin softeners, because they are all natural lubricating substances, can also be treated as a separate category. However, they are also classified into different ionic categories based on the ionicity of the emulsifiers used. . There are two main types of polymer softeners: polyethylene and silicone. The variety of polyethylene softeners is relatively single, and the dosage is also small. The most commonly used softeners are mainly silicone softeners. Since the main chain of polysiloxane is a very flexible helical linear structure, it can rotate freely 360 degrees, and the energy required for rotation is almost zero. Therefore, the molecular structure of polysiloxane is in line with the softness mechanism of textiles. It can not only reduce the static and dynamic friction coefficients between fibers, but also has very small intermolecular forces and reduces the surface tension of fibers. It is an ideal textile softening finishing agent. Ideal material. Silicone softeners are the fastest growing softener variety in recent years.
4. Style characteristics of the trial samples
In addition to soap, sulfonated oil, etc., the main components of anionic softeners are: Cationic compounds or anionic and nonionic compounds with long-chain alkanes such as sodium stearyl sulfonate succinate and stearyl sulfate. It generally has good wettability and thermal stability, can be used in the same bath with fluorescent whitening agents, and can be used as a softener for extra white fabrics. It is also more suitable for cellulose fibers and can give fabrics better water absorption. However, its adsorption to fibers is similar to direct dyes and is relatively weak, so the softening effect is poor and it is easy to be washed away. In addition, due to its softening effect in the bath, it can be used in silk scouring to prevent abrasions (ash wounds).
5. Nonionic softeners
Nonionic softeners are generally polyoxyethylene esters of ten acids (or alcohols) ( or ether), fatty esters of pentaerythritol or sorbitan. Since non-ionic softeners have poorer adsorption to fibers than ionic softeners, they can only play a smoothing role. However, it can be used with ionic softeners, has good compatibility with other materials, good stability to electrolytes, and does not have the disadvantage of yellowing fabrics. It can be used as a non-durable softening finishing agent, and can also be used as synthetic fiber spinning oil. ���, thus making the lotion transparent. It is precisely the particle size of its particles that is only 1/10 of the particle size in ordinary emulsions, which increases the number of effective particles in the microemulsion by 103 times (if the concentration is the same). The contact opportunities between the microemulsion and the fabric are greatly increased, and in the fabric The surface spreads well and easily penetrates into the fiber. This product therefore imparts good internal softness to the fabric, which is also more durable. Microemulsion products generally have better water solubility, storage stability, heat resistance, and shear resistance stability.
Although commonly used diamino silicone softeners have good softening effects, their whiteness, water absorption, and easy stain removal are poor, and this becomes serious as the amino functional groups in the polymer increase. In order to improve these shortcomings, it can be achieved by changing the type and number of amino functional groups. Changing the type of amino functional group is mainly to change the primary amino group into a secondary or tertiary amino group, such as N-propylcyclohexylamine (secondary amine) and N-propylpiperazine (tertiary amine) modified silicone softener Has been developed for use in fabric finishing. This type of softener can reduce yellowing during baking, and is less hydrophobic than silicone softeners with primary amine functional groups, but makes the fabric feel somewhat dry. Mainly used for soft finishing of bleached fabrics and light-colored fabrics.
In addition, in order to obtain an ultra-smooth hand, both ends of the dimethylsiloxane macromolecule are end-capped with amino modification, which can form a very neat directional arrangement on the fabric, thereby obtaining an excellent smooth hand; If some of the side chain groups and both end groups of polysiloxane are substituted with amino modification and used as a fabric finishing agent, it can make the fabric more soft. Nowadays, silicone softeners are developing rapidly, with more and more varieties, prices have also dropped, and the number of applications using silicone softeners has increased significantly. In addition to the various types of silicone softeners mentioned above, there are also silicone softeners such as epoxy-modified, amide-modified, and carboxyl-modified. Since there should be very few at present, we will not introduce them one by one here.
9. Low molecular polyethylene emulsion
This type of softener is made of low molecular polyethylene after oxidation treatment and then emulsification. product. It has a certain affinity for fibers, giving the fabric a smooth feel. It can be used in the same bath with resin, and can improve the tear strength and wear resistance reduced by resin finishing. It is a cheap fabric before the popularization and application of silicone softeners. Soft and smooth additive. At present, this type of softener is generally not used alone. It can be used as a compound component of various softeners, and can also be used as a stabilizer in hydroxyl silicone emulsion.
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