Thirdly, it is used as an electrolyte for the dyes to get fixed to the cellulose fibres. Common Salt is a chemical compound belonging to the larger class of salts composed primarily a mineral of sodium chloride NaCl.
Because of its efficiency and less cost. These two are essentially the same in terms of their place as an inorganic salt. Because of the presence of sodium cation in both the salts.
You must be logged in to post a comment. Saravanan K July 20, Like 1. Need for salt in textile chemical processing The purpose of the information given here is to help in understanding the role of using salt during Textile Wet Processing especially in dyeing.
Why do use salt in textile chemical processing? Types of salt: Two types of industrial salt called Vacuum and rock salt are available for textile dyeing. The reactive dyestuff exhaustion is high during dyeing because of adding salt. Reactive dyes have a lower affinity towards cellulosic material. Because liposomes are amphoteric compounds, they can wrap up various types of polar and nonpolar solutes. The polar solutes can be embedded within the aqueous compartment, while nonpolar solutes can be trapped between the bilayer 7.
Liposomes are nontoxic, harmless, and biodegradable 8 , 9. Owing to the encapsulation and sustained-release abilities of liposomes, they are widely used in pharmaceuticals, textiles, detergents, foodstuffs, cosmetics and other fields In textiles, liposome technology is mainly applied in the following six aspects: wool dyeing 11 , durable aroma finishing, textile protection 12 , parasiticide preparation, antibacterial drug preparation and phase-transition material preparation Liposomes have been examined as a means of delivering dyestuffs to fibers in a cost-effective and environmentally sensitive manner Compared with traditional retarding agents, liposomes can slowly release a microencapsulated dye to increase the retarding effect, making them a good alternative to commercial levelling agents Liposomes have been investigated as vehicles in wool dyeing with acid, disperse and metal-complex dyes, and wool and wool blend dyeing with liposomes resulted in better quality and energy savings and lower environmental impact 5 , 15 , 16 , 17 , Recently, Marti et al.
Research results from Sheveleva et al. The affinity of reactive dyes is generally low. Reactive dyes have a negative charge in water, and cellulose fibers are also electronegative in water. Therefore, electrostatic repulsion between cellulose fibers and anionic dyes can prevent reactive dyes from dyeing cellulose fibers. At present, a dyeing promoter is commonly used during reactive-dye dyeing. Inorganic salts anhydrous sodium sulfate or sodium chloride are the most commonly applied dyeing promoters.
The cations of inorganic salts adsorb to the cellulose fiber surface, and the negative charge of the cellulose fiber is weakened.
Thus, cellulose fibers can be dyed with anionic reactive dyes. However, inorganic salts are also bound resulting in severe salt pollution of the water body. To solve the above problems, scholars have conducted the following work: 1 Low-salt or salt-free dyeing with reactive dyes such as the Sumifix Supra series of dyes from Japan Sumitomo Corporation has been developed.
However, this kind of dye easily results in unlevel dyeing, which increases the dye dosage and dyeing cost. Therefore, changes in the dye structure cannot effectively solve the problem of high-salt dyeing of reactive dyes. However, cationic modification affects the level-dyeing property of cellulose fibers, and the most important disadvantage of this modification is that it is difficult to use for large-scale application However, the pretreatment of cellulose fibers with an auxiliary is a complex production process that also leads to low friction fastness and high stiffness of the dyed fabrics.
Meanwhile, low-salt dyeing auxiliaries are prone to yellow in high temperature and are unfit dyes for light-color fabrics. For example, ethylenediamine tetraacetic acid was studied as an alternative to inorganic salts In summary, the above efforts still have some problems, although the dosage of inorganic salt required was reduced by varying degrees.
For that reason, nontoxic, harmless and biodegradable liposomes were synthesized by using soybean lecithin and stearamide as raw materials, and were used to promote the dyeing of cotton fibers with reactive dyes by encapsulating reactive dyes in liposomes as an alternative to sodium chloride. The environmental pollution caused by the use of traditional dyeing promoter can be reduced. In addition, liposomes can also improve the level-dyeing effect of reactive dyes dyeing compared with sodium chloride because liposomes can encapsulate reactive dyes in the lipid bilayer and have long-term and sustained-release effect.
In this work, neutral nanoliposomes abbreviated NL and cationic nanoliposomes abbreviated CL were applied as novel dyeing and level-dyeing promoters to enhance the dyeing effect of reactive dyes on cotton-fiber dyeing by encapsulating reactive dyes in nanoliposomes as an alternative to inorganic salt. The morphology, particle size and zeta potential of CL and NL were studied; the dyeing effects of three kinds of dyeing and level-dyeing promoters CL, NL and NaCl were compared; and the dyeing-promotion and level-dyeing mechanisms of NL and CL on reactive dyes were analyzed.
Beijing, China. Stearamide was purchased from Sigma Chemical Co. Qiqihar, China. All other reagents were analytically pure and used as received. NL and CL were prepared following a thin-film hydration method. Finally, a thin lipid layer was formed on the sides of the round-bottom flask. The round-bottom flask was dried overnight in a vacuum drying oven to completely remove residual chloroform.
Then, deionized water was added to the bottom of the round-bottom flask, and the thin-film lipid was adequately hydrated and completely separated from the round-bottom flask through high-speed stirring 25 , Dyeing experiments were performed in a thermostat water bath with a dye-bath ratio of A colloidal solution of NL and CL was appropriately diluted, and then, a special copper net covered with a carbon film was dipped into the solution.
NL and CL colloidal solutions were diluted to 1. A lower U value represents a better level-dyeing property of the dyed fabric The NL and CL were prepared and characterized at the beginning of this work.
NL and CL particles were basically spherical, and their particle sizes were mainly uniform. Compared with that of NL, the dispersity of CL was also better due to the repulsive interactions between CL particles. The average particle size of NL was We think that the nanoliposome particle sizes in Table 1 are more accurate.
The dyeing effect on cellulose fibers using NaCl, NL and CL as dyeing and level-dyeing promoters under the optimal conditions was studied, and the results are shown in Table 2. For the level-dyeing promotion, the enhancement of level-dyeing from high to low was as follows: CL, NL, NaCl, and without any dyeing and level-dyeing promoters.
Liposomes, especially CL, had a great level-dyeing promoting effect on cotton fibers, although the dyeing promoting effect was not as good as that of NaCl. Therefore, NL and CL obviously perform the level-dyeing promoting role in the dyeing process of reactive dyes.
Table 2 also shows that only light-color fabrics can be dyed using NL and CL as dyeing and level-dyeing promoters. NaCl must be used as a dyeing promoter to obtain dark-color fabrics. Liposomes, especially CL, have remarkable level-dyeing promoting effects on cotton fibers compared with NaCl and without any dyeing and level-dyeing promoters.
Clearly, the soaping fastness and friction fastness were not much different, although different dyeing and level-dyeing promoters were used in the reactive-dye dyeing process.
Reactive dyes have a negative charge in water, and cellulose fibers are electronegative in water. Therefore, the electrostatic repulsion between cellulose fibers and anionic reactive dyes can prevent reactive dyes from dyeing cellulose fibers. NaCl acts as a dyeing promoter in traditional cotton fabric dyeing with reactive dyes. Thus, the electrostatic repulsion between cellulose fibers and anionic reactive dyes is reduced, allowing cellulose fibers to be dyed with anionic reactive dyes.
However, the use of a large amount of NaCl results in severe salt pollution of the water body. As far as the intermolecular force between two molecules or ions is concerned, Coulomb force electrostatic force is much larger than van der Waals force.
When cellulose fibers with negative charges are dyed with reactive dyes, the large Coulomb repulsion between dyes and fibers makes the dyes could not approach the fiber surface. NL and CL can encapsulate and transport reactive dyes into fiber surface, and the released reactive dyes are quickly adsorbed by cellulose fibers due to van der Waals force.
Therefore, NL and CL can act as dyeing promoter during the dyeing of cellulose fibers. The larger the thickness of vesicle bilayer, the smaller the electrostatic repulsion of fiber and dye, but the harder the release of the dye from the vesicle.
The dyeing-promotion and level-dyeing mechanisms of NL in reactive-dye dyeing of cellulose fibers are presented Fig. The dyeing and level-dyeing promotion mechanisms of NL are entirely different from those of NaCl. NL has a lipid bilayer structure, which can extensively encapsulate various polar and nonpolar solutes.
At lower temperatures, the dye is in a less hydrated environment in lecithin liposomes, which corresponds to a location in the liposome membrane, probably nears the polar head groups.
With increasing temperature, the dye relocates to a more hydrated environment, and is released from the liposome membrane to the aqueous solution 28 Fig. Cellulose fibers and reactive dyes are all negatively charged in water, and the electrostatic repulsion between cellulose fibers and reactive dyes can prevent reactive dyes from dyeing cellulose fibers.
After reactive dyes are encapsulated by NL, reactive dyes are converted into microcapsule dyes with electrically neutral NL as the wall materials. There are no electrostatic repulsion between cellulose and NL, so reactive dyes can be transported to the surface of cellulose fibers by molecular motion of the electroneutral NL.
With the increase of temperature, the diffusion activation energy and the uptake of reactive dyes are also increased. The reactive dyes are slowly released from the NL membrane to reach the surface of the cellulose fibers, and covalently react with the hydroxyl groups of cellulose fibers under alkaline conditions.
In this way, the reactive dyes are firmly fixed to the cellulose fibers. NL can play a dyeing promoter role in the dyeing process of reactive dyes.
In addition, if the dyeing rate is too fast, the unlevel-dyeing of cellulose fibers would occur. It usually makes much more sense to try increasing the reaction temperature than to start messing around with adding different salts, if this is your problem. In tie-dyeing cotton, rayon, and silk, using fiber reactive dyes such as Procion MX or Sabracron F, there is no need to use salt at all.
Other dyes will require salt, but it is best to use fiber reactive dyes, for tie-dyeing cellulose fibers such as cotton and rayon, because they are both easier to use and produce much more satisfactory results. Again, be sure to dissolve the dye first without salt, as it may be impossible in the presense of the salt. Direct dye Direct dye is the portion of all-purpose dye , such as Rit brand dye, which dyes cotton and other cellulose fibers. The brighter acid dye portion just washes out of these fibers, but will dye animal fibers such as wool, and also nylon.
You certainly should use salt when dyeing with direct dye, following the manufacturer's instructions. It is best to start with no salt in your hot water bath of water plus fiber plus dye, then gradually add the salt, in several portions, at intervals of perhaps ten minutes.
Dyes for Protein fibers Again, always pay strict attention to the manufacturer's instructions, unless you have better information.
0コメント