Yaa Whitening Agent: Properties, Function, Machinery In Addition To Usages (Part-2)
Tuesday, 18 December 2018
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Whitening Agent: Properties, Function, Mechanism together with Usages (Part-2)
Authors: Md. Mosharaf Hossain
Kiriti Kingkar Mondal
Tawhidul Islam
Dept. of Textile Engineering
Primeasia University, Dhaka
Kiriti Kingkar Mondal
Tawhidul Islam
Dept. of Textile Engineering
Primeasia University, Dhaka
Previous Part
Chemistry of whitening agent:
About 80% of all OBAs produced are derived from stilbene derivatives, the latter absorbing inwards the ultra purplish regions at (α) = 342 nm. All optical brighteners are dyestuffs, but inwards house of the chromophoric arrangement which is the feature for dyes, it contains a fluorescening arrangement together with similar a normal dye sure enough substituents which promote the affinity, depending on the type of fiber on which it is applied. In this manner, brighteners which are suitable for cotton fiber are to a greater extent than or less noun derivatives of diaminostilbene disulphonic acid. The stilbene derivatives tin forcefulness out live introduce inwards 2 isomeric forms, ie inwards the Cis configuration together with inwards the Trans configuration .Optical brighteners inwards the Trans shape tin forcefulness out live made both inwards the pulverisation together with liquid form.The Cis form, which is chop-chop formed nether the activity of calorie-free from the trans shape volition non teach on cotton fiber together with for this reason, the solutions of this whitener is protected against light. Many of the optical brighteners are derived from the heterocyclic compounds containing nitrogen atoms.
Fluorescence is produced yesteryear the absorption of radiations having a high unloosen energy on the component division of the molecule, which re – emits this radiations of lower unloosen energy i.e. of longer moving ridge length, the departure inwards unloosen energy beingness transformed inwards to kinetic energy. To enable a molecule to fulfill this function, it must live built according to sure enough construction principles. For illustration Anthranilic acid has rattling rigid bluish purplish fluorescence inwards the aqueous solution, but withal unsuitable as a brightener. Most of the brightener volition hardly fluoresce inwards pulverisation form; their fluorescence volition exclusively appear inwards solution. There are some types, which volition non fluoresce inwards solution together with volition exclusively demonstrate this belongings later they convey been applied on the fiber. Thus, it tin forcefulness out live concluded that fluorescence is non exclusively depended on the construction of the molecule but likewise on its condition. Whether a fluorescent marrow is suitable as brightener tin forcefulness out exclusively live determined later it has been applied to the textile fiber. Apart from this the production must come across sure enough demands inwards abide by of properties such as fastness to washing together with calorie-free etc .On comparering unlike textile fabrics treated alongside unlike brighteners together with processing to a greater extent than or less the same brightness departure inwards hue tin forcefulness out live deleted, since the human oculus is peculiarly sensitive to departure inwards whiteness. If an optically brightened textile alongside radish white shade is compared alongside some other textile having a greenish white shade both of which appear to live as brilliant if viewed inwards daylight which is incident from a northerly direction, it volition live seen that the greenish shade volition appear to a greater extent than brilliant together with thence the radish i inwards vivid sunlight.
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| Fig: Example of an optical brightener's structure |
Commercial cite of whitening agent inwards textile
Product Name | Strength | Application | Shade | Area of application |
Kolorcron BA Powder | 450 E Value | Cellulose-Exhaust inwards H2O2 bleach. Polyami- de/Wool/ Silk –Exhaust Single bathroom scouring bleaching at high Temp. alongside Hydro. | Neutral to Bluish White | Cellulose, Polyam- ide, Wool/ Silk |
Kolorcron WHN | 180 E Value | Cellulose-Exhaust inwards H2O2 bleach. Polyami- de/Wool/ Silk –Exhaust Single bathroom scouring bleaching at high Temp. alongside Hydro. | Neutral to Bluish White | Cellulose, Polyam- ide, Wool/ Silk |
Kolorcron 4BB | 125 E Value | No Padding application Exhaust at 80* C & above | Bluish Violet White | Cellulose Fibers |
Kolorcron BA Liquid | 125 E Value | Cellulose-Exhaust inwards H2O2 bleach. Polyami- de/Wool/ Silk –Exhaust Single bathroom scouring bleaching at high Temp. alongside Hydro. | Neutral to Bluish White | Cellulose, Polyam- ide, Wool/ Silk |
Kolorcron CXT Liquid | 100 E Value | Padding & Low Temp Exhaust application. Single bathroom scouring together with Bleaching at high Temp. | Bluish Violate White | Cellulose Fiber & Cellulose Blend |
Kolorcron S | 70 E Value | No padding application Exhaust 40* - 60* C & regenerate | Bluish White | Cellulose Fiber & Cellulose Blend |
Chemical Constitution of Optical Brighteners
Optical brighteners are unremarkably derivatives of:
Fluorescence of Optical Brighteners Mechanism
Brightening is neither bleaching nor blueing. Fluorescent colours volition reverberate to a greater extent than calorie-free than they tin forcefulness out absorb from the visible hit of the spectrum. Whiteness tin forcefulness out likewise live increased yesteryear using substances which would give colourless solutions but were strongly fluorescent. Fluorescence is produced yesteryear the absorption of radiations having a high unloosen energy on the component division of the molecule, which re-emits this radiations as a radiations of lower unloosen energy i.e. of longer wavelength, the departure inwards unloosen energy beingness transformed inwards to kinetic energy. To enable a molecule to fulfill this function, it must live built according to sure enough structural principles. For illustration Anthranilic acid has rattling rigid bluish purplish fluorescence inwards its aqueous solution, but withal unsuitable as a brightener.
Most of the brighteners volition hardly fluoresce inwards pulverisation form; their fluorescence volition exclusively appear inwards solution. There are some types, which volition non fluoresce inwards solution together with volition exclusively demonstrate this belongings later they convey been applied on the fiber. Thus, it tin forcefulness out live concluded that fluorescence is non exclusively subject on the construction of the molecule but likewise on its condition. Whether a fluorescent marrow is suitable as a brightener tin forcefulness out exclusively live determined later it has been applied to the textile fiber. Apart from this the production must come across sure enough demands inwards abide by of properties such as fastness to washing together with calorie-free etc. On comparison unlike textile fabrics treated alongside unlike brighteners together with possessing to a greater extent than or less the same brightness, differences inwards hue tin forcefulness out live detected, since the human oculus is peculiarly sensitive to differences inwards whiteness. If an optically brightened textile alongside reddish white shade is compared alongside some other textile having a greenish white shade, both of which appear to live as brilliant if viewed inwards daylight which is incident from a northerly direction, it volition live seen that the greenish shade volition appear to a greater extent than brilliant than a reddish i inwards vivid sunlight.
On the other hand, if both fabrics are seen following inwards a room at a distance of several yards from the window where at that topographic point volition live lower proportion of ultra purplish light, the reddish shade volition appear to live stronger. These rigid variations volition non live observed inwards the instance of a neutral shade, ie, inwards sunlight the neutral white shade appears slightly superior to the reddish together with slightly inferior to the greenish shade, where as the contrary lawsuit is obtained inwards reduced twenty-four sixty minutes catamenia light. The same lawsuit tin forcefulness out live observed when comparison optically brightened stuff having a crude oil surface alongside such stuff which has a polish surface. While an optically brightened polish stuff of a reddish shade may appear equal inwards brilliance to that of a similar stuff alongside a greenish shade, it volition live seen that inwards the instance of a crude oil surface the reddish stuff volition appear to live to a greater extent than brilliant.
- Triazine-stilbenes (di-, tetra- or hexa-sulfonated)
- Coumarins
- Imidazolines
- Diazoles
- Triazoles
- Benzoxazolines
- Biphenyl-stilbenes
Fluorescence of Optical Brighteners Mechanism
Brightening is neither bleaching nor blueing. Fluorescent colours volition reverberate to a greater extent than calorie-free than they tin forcefulness out absorb from the visible hit of the spectrum. Whiteness tin forcefulness out likewise live increased yesteryear using substances which would give colourless solutions but were strongly fluorescent. Fluorescence is produced yesteryear the absorption of radiations having a high unloosen energy on the component division of the molecule, which re-emits this radiations as a radiations of lower unloosen energy i.e. of longer wavelength, the departure inwards unloosen energy beingness transformed inwards to kinetic energy. To enable a molecule to fulfill this function, it must live built according to sure enough structural principles. For illustration Anthranilic acid has rattling rigid bluish purplish fluorescence inwards its aqueous solution, but withal unsuitable as a brightener.
Most of the brighteners volition hardly fluoresce inwards pulverisation form; their fluorescence volition exclusively appear inwards solution. There are some types, which volition non fluoresce inwards solution together with volition exclusively demonstrate this belongings later they convey been applied on the fiber. Thus, it tin forcefulness out live concluded that fluorescence is non exclusively subject on the construction of the molecule but likewise on its condition. Whether a fluorescent marrow is suitable as a brightener tin forcefulness out exclusively live determined later it has been applied to the textile fiber. Apart from this the production must come across sure enough demands inwards abide by of properties such as fastness to washing together with calorie-free etc. On comparison unlike textile fabrics treated alongside unlike brighteners together with possessing to a greater extent than or less the same brightness, differences inwards hue tin forcefulness out live detected, since the human oculus is peculiarly sensitive to differences inwards whiteness. If an optically brightened textile alongside reddish white shade is compared alongside some other textile having a greenish white shade, both of which appear to live as brilliant if viewed inwards daylight which is incident from a northerly direction, it volition live seen that the greenish shade volition appear to a greater extent than brilliant than a reddish i inwards vivid sunlight.
On the other hand, if both fabrics are seen following inwards a room at a distance of several yards from the window where at that topographic point volition live lower proportion of ultra purplish light, the reddish shade volition appear to live stronger. These rigid variations volition non live observed inwards the instance of a neutral shade, ie, inwards sunlight the neutral white shade appears slightly superior to the reddish together with slightly inferior to the greenish shade, where as the contrary lawsuit is obtained inwards reduced twenty-four sixty minutes catamenia light. The same lawsuit tin forcefulness out live observed when comparison optically brightened stuff having a crude oil surface alongside such stuff which has a polish surface. While an optically brightened polish stuff of a reddish shade may appear equal inwards brilliance to that of a similar stuff alongside a greenish shade, it volition live seen that inwards the instance of a crude oil surface the reddish stuff volition appear to live to a greater extent than brilliant.