**3. Types of functional dyes**

*Dyes and Pigments - Novel Applications and Waste Treatment*

**responsible for colour change**

Electricity (gain and loss of electron)

Heat (absorption spectrum of a thermochromic molecule)

**Suitable methods of application for textiles**

Exhaust, Continuous method, micro encapsulation

dry cure method

exhaust dyeing, solgel method, prior addition to electrospinning solution.

encapsulation

Melt processing technique, physically dispersed in form of supramolecular aggregates in a matrix in a polymer, Covalent insertion of chromophoric units

Light Exhaust and pad

pH Conventional

UV rays Micro

Deformation (elongation and compression) of polymer on which applied

**Application in textiles**

information or for camouflaging purposes

Thermoregulation, Brand forgery detection

Camophlaging textiles, window curtains, UV detective fabric

Footwear and shaped garment industry

Medical textiles [58–60]

Packaging [61–63]

Coating For displaying

**References**

[23–30]

[31–42]

[43–57]

[64–66]

**S. No Smart Dyes External Stimuli** 

1. Electrochromic dye

2. Thermochromic dye

3. Photochromic dye

4. Chemo chromic dyes

5. Solvatochromic dye

6. Mechanochromic dye

**104**

**2.6 Mechanochromic dyes**

*Types of smart dyes used in textile industry.*

**Table 1.**

Mechanachromism is a phenomenon in which a polymer changes it colour due to deformation such as elongation and compression. Elongation and compression occur due to the change in pH, temperature. Mechanachromic dyes are the organic dyes which is applied on polymer and causes changes in colour due to certain mechanical pressure. Mechanochormic dye cannot act alone it require a polymer (material) because only polymer can deform (elongate or compress). In a study 1,4-bis (R-cyano-4- methoxystyryl)-2,5-dimethoxybenzene9 (C1-RG, F) has been incorporated in polyethylene using melt processing technique [64]. In another research mechanochromic polymers have been developed by incorporating a dye filled microcapsules [65]. In a study Polydiacetylenes (PDA) was synthesised by thermal polymerisation of diphenyl sulphide containing bisdiacetylene. It is reported in that study that PDA changes its colour from blue to red due to elongation and compression. In the cool (non-extended state) form, the material has a

Functional groups like -OH, -NH2, − COOH of dyes offer various functional properties when applied onto the textile [67]. Both natural and synthetic dyes can perform various functions after application on textiles. Now days more emphasise is being given to the green and sustainable functional dyes which directly comes from nature. Types functional dyes are as follows:

#### **3.1 Antimicrobial/antibacterial dye**

Microbes and bacteria cause several kinds of dermal infection, body odour and several other severe health issue [68]. Antimicrobial dyes provide the protection from variety of micro-organisms like gram-positive bacteria such as *Staphylococcus aureus, Streptococcus epidermidis and Bacillus cereus* and gram-negative bacteria such as *Escherichia coli, Klebsiella pneumonia, Shigella flexneri and Proteus vulgaris* and other microbes [69]. A large no. of antimicrobial dyes possesses antimicrobial activity against human pathogen but very few have been reported for textiles. Number of researches have been conducting to find out the antimicrobial properties in various synthetic and natural dyes. Various studies reported that synthetic dyes such as direct, cationic, reactive and disperse dyes provides antimicrobial property to the fabric after dyeing. In a study it was found that Direct Blue 168 dye and copper sulphate as mordanting agent incorporate antimicrobial properties in the acrylic fabric [70]. Similarly, antimicrobial dyes based on azo heterocyclic and/or homocyclic Systems also have biocidal behaviour [71]. Multifunctional antimicrobial dyes have also been developed by adding a functional gp (quaternary ammonium salt group) to a traditional aminoanthraquinoid dye [72]. Most research has been focused on polycationic systems that are more supple for modification. Reactive dyes form homopolar bonds with textile substrates. The synthesised thiazolidinone derivatives exhibiting antimicrobial properties. Synthesised monoazo disperse dyes showed better results against gram positive as well as gram negative bacteria [73]. Application of natural dyes on textiles also offer antimicrobial textiles. Phenolic compounds such as anthraquinones, flavonoids, tannins, naphthoquinones and others in natural dyes are responsible for the antimicrobial activity. When these phenolic compounds reacted with textiles, formation of complex form. This complex hinders (bacteriostatic) or kill (bactericidal) the enzyme production in microbes. At present more emphasis is being given to antimicrobial activity of natural dye due to various environmental concern. From various studies it was found that natural dyes extracted from Pomegranate (*Punica granatum)* peels, Henna (*Lawsonia inermis*) leaves, *M. composita* leaves, Madder (*Rubia tinctorium*) root, safflower, *Rumex maritimus (*Golden dock*)*, *Indigo (Quercus infectoria) leaves,* Berberine provides antimicrobial properties to the fabric. Application of Natural dyes such as peony, clove, *Coptis chinensis* (Chinese goldthread) and gallnut on fabric also provides protection against *Staphylococcus aureus* due to presence of phenolic compounds [74–78].

Perspiration cause formation of bacterial colonies on textiles, which led to bad odour [79]. Various natural dyes can act as a barrier to form these colonies. Natural dyes such as pomegranate, coffe arabica, *Cassia tora*, gardenia Indigo, Peony, clove and pomegranate (*Punica granatum*) reported as a good deodorising agent when applied on textiles [80–82]. Natural dyes extracted from gallnut also act as a deodoriser for textile due to the presence of gallotannin [83].

There is no. of methods to impart antimicrobial dyes on textiles. For proper bonding of textile and dye, the textile surface can be modified through various treatments such as treatment with chemicals, chitosan, enzymes, UV radiation, ultrasound [84]. Application methods can be altered with regard to type of fibre dye and the end use. Therefore, researchers should consider the structure of dye and fibre. The researchers should also have knowledge how this bonding of fibre and dye affect the fabric properties. The products of Health, hygiene as well as medical textiles comes under the application area of antimicrobial dyes.

#### **3.2 UV protective dyes**

Presently UV ryas are causing various harmful effects. UV protective dyes enhance the UPF (Ultraviolet Protection Factor) of the textiles. UPF means how much a fabric can protect the wearer from harmful UV rays. In general, all dyes act as a UV absorber because spectral region falls into UV region. Various kind of synthetic dyes are commercially available to enhances the UPF of the fabric. Direct, vat and reactive dyes increases the UPF of fabric [85–87]. Various researches reported that natural dyes can also enhances the UPF of the fabric. Absorption characteristics of natural dyes generally determines the UPF of the fabric [88]. Phenolic compounds in natural dyes work as UV protective agent as these molecules absorb the UV radiation. For instance, *R. maritimus, M. philippinensis, K. lacca, A. catechu and A. nilotica* have tannin content (phenolic compond) thus provide good UPF to the fabric. It is also reported in various studies that, Natural dyes from eucalyptus leaf extract, *Xylocarpus granatum* (*Cedar Mangrove*) bark extract, blossoms of broom (*Cytisus scoparius*) and dandelion (*Taraxacum officinale*), Weld, woad, logwood lipstick tree, madder, brasil wood, and cochineal, gromwell roots, *Acacia*, henna dye extract, chitosan and turmeric dye gallnuts, areca nuts, and pomegranate peels banana peel *babool, ratanjot*, annatto and *manjistha* enhances the UPF of textiles [89–95]. Mordants are used with natural dyes to enhances the fastness properties of the dyes. Several studies reported the positive impact of mordant on the UPF of the fabric. But very few studies also reported the negative impact of mordant on the UPF of the fabric. It means type of the mordant, mordanting method also affect the UPF of the fabric [96, 97]. In case of both synthetic as well as natural dyes, several parameters such as concentration of dye, exhaustion time and extraction and exhaustion temperature affect the UPF of fabric [98, 99]. For instance, it is reported that with the increase of concentration of dye, the UPF of dyed fabric also increases. While exhaustion time and temperature are not causing significant change in the UPF of the fabric. Various studies also report the correlation between the dyeing parameters and UPF.

In a study exhaust method was used for the application of herbal plant extract to enhance the UV protection of the fabric. Madder and cutch dye was applied on nettle fabric using exhaust dyeing method [100]. Pad dry cure method were also used for application of UV protective dye [101].

Application of UV protective dyes can be extended mainly to the clothing of outdoor activities such as fishing, farming, horticulture, gardening, building construction, road construction, postcard distribution, oil production field, military defence services, skiing, police work, professional cycling, surfing [102].

**107**

**Table 2.**

*Application of Smart and Functional Dyes in Textiles DOI: http://dx.doi.org/10.5772/intechopen.96045*

**Source Suitable methods** 

**Natural source:** Pomegranate (*Punica granatum)* peels, Henna (*Lawsonia inermis*) leaves, *M. composita* leaves, Madder (*Rubia tinctorium*) root, safflower, *Rumex maritimus (*Golden dock*)*, *Indigo (Quercus infectoria) leaves,* Berberine, peony, clove, *Coptis chinensis* (Chinese goldthread) and gallnut *Synthesised source:* direct, cationic, reactive and disperse dyes, Direct Blue 168 dye and copper sulphate, dyes based on azo heterocyclic and/or homocyclic Systems, developed by adding a functional gp (quaternary ammonium salt group) to a traditional aminoanthraquinoid dye, polycationic systems, Synthesised thiazolidinone derivatives, Synthesised monoazo disperse dyes

*Natural source: R. maritimus, M. philippinensis, K. lacca, A. catechu and A. nilotica* eucalyptus leaf extract, *Xylocarpus granatum* (*Cedar Mangrove*) bark extract, blossoms of broom (*Cytisus scoparius*) and dandelion (*Taraxacum officinale*), Weld, woad, logwood lipstick tree, madder, brasil wood, and cochineal, gromwell roots, *Acacia*, henna dye extract, chitosan and turmeric dye gallnuts, areca nuts, and pomegranate peels, banana peel, *babool, ratanjot*, annatto

and *manjistha*

and reactive dyes

*Synthesised source:* Direct, vat

Saffron flower waste, onion skin, henna, myrobalan, silver oak leaf, madder, wall nut, dholkanali and yellow roots

**Natural source:** Pomegranate peel with polyvinyl alcohol **Synthesised source:** *4*-*Amino*-*N, N*-*diethyl*–*3 methyl benzamide* (MD).

**of application for textiles**

Treatment of textiles surface with chemicals, chitosan, enzymes, UV radiation, ultrasound

Exhaust, pad dry cure and microencapsulation

Simultaneous dyeing [105–110]

Exhaust, microencapsulation **References**

[70–84]

[85–104]

**S. No Functional Dyes**

1. Antimicrobial dyes

2. UV protective dyes

3. Moth repellent dyes

4. Mosquito

repellent dyes

*Types of functional dyes used in textile industry.*


*Dyes and Pigments - Novel Applications and Waste Treatment*

**3.2 UV protective dyes**

deodoriser for textile due to the presence of gallotannin [83].

Perspiration cause formation of bacterial colonies on textiles, which led to bad odour [79]. Various natural dyes can act as a barrier to form these colonies. Natural dyes such as pomegranate, coffe arabica, *Cassia tora*, gardenia Indigo, Peony, clove and pomegranate (*Punica granatum*) reported as a good deodorising agent when applied on textiles [80–82]. Natural dyes extracted from gallnut also act as a

There is no. of methods to impart antimicrobial dyes on textiles. For proper bonding of textile and dye, the textile surface can be modified through various treatments such as treatment with chemicals, chitosan, enzymes, UV radiation, ultrasound [84]. Application methods can be altered with regard to type of fibre dye and the end use. Therefore, researchers should consider the structure of dye and fibre. The researchers should also have knowledge how this bonding of fibre and dye affect the fabric properties. The products of Health, hygiene as well as medical textiles comes under the application area of antimicrobial dyes.

Presently UV ryas are causing various harmful effects. UV protective dyes enhance the UPF (Ultraviolet Protection Factor) of the textiles. UPF means how much a fabric can protect the wearer from harmful UV rays. In general, all dyes act as a UV absorber because spectral region falls into UV region. Various kind of synthetic dyes are commercially available to enhances the UPF of the fabric. Direct, vat and reactive dyes increases the UPF of fabric [85–87]. Various researches reported that natural dyes can also enhances the UPF of the fabric. Absorption characteristics of natural dyes generally determines the UPF of the fabric [88]. Phenolic compounds in natural dyes work as UV protective agent as these molecules absorb the UV radiation. For instance, *R. maritimus, M. philippinensis, K. lacca, A. catechu and A. nilotica* have tannin content (phenolic compond) thus provide good UPF to the fabric. It is also reported in various studies that, Natural dyes from eucalyptus leaf extract, *Xylocarpus granatum* (*Cedar Mangrove*) bark extract, blossoms of broom (*Cytisus scoparius*) and dandelion (*Taraxacum officinale*), Weld, woad, logwood lipstick tree, madder, brasil wood, and cochineal, gromwell roots, *Acacia*, henna dye extract, chitosan and turmeric dye gallnuts, areca nuts, and pomegranate peels banana peel *babool, ratanjot*, annatto and *manjistha* enhances the UPF of textiles [89–95]. Mordants are used with natural dyes to enhances the fastness properties of the dyes. Several studies reported the positive impact of mordant on the UPF of the fabric. But very few studies also reported the negative impact of mordant on the UPF of the fabric. It means type of the mordant, mordanting method also affect the UPF of the fabric [96, 97]. In case of both synthetic as well as natural dyes, several parameters such as concentration of dye, exhaustion time and extraction and exhaustion temperature affect the UPF of fabric [98, 99]. For instance, it is reported that with the increase of concentration of dye, the UPF of dyed fabric also increases. While exhaustion time and temperature are not causing significant change in the UPF of the fabric. Various studies also report the correlation between

In a study exhaust method was used for the application of herbal plant extract to enhance the UV protection of the fabric. Madder and cutch dye was applied on nettle fabric using exhaust dyeing method [100]. Pad dry cure method were also

Application of UV protective dyes can be extended mainly to the clothing of outdoor activities such as fishing, farming, horticulture, gardening, building construction, road construction, postcard distribution, oil production field, military defence services, skiing, police work, professional cycling, surfing [102].

**106**

the dyeing parameters and UPF.

used for application of UV protective dye [101].

#### **Table 2.**

*Types of functional dyes used in textile industry.*

UV protective dye can also be applied to the clothing of Indoor workers who are potentially exposed to UV radiation for example in hospitals where UV radiation is required for some kind of treatments in some laboratory works, plasma torch operating, printing, lithographing, painting, wood curing, plastic working, in some cases food industry also [103]. Army personnel who have been working in extreme climate conditions also experiences intense solar radiation with terrible heat stress also requires protection from UV rays [104].

#### **3.3 Moth proof and mosquito repellent dyes**

Moth proof and mosquito repellent dyes provides protection against moths and mosquitos after application on textiles. Synthetic moth proof or mosquito repellent are generally available in colourless form. Therefore, moth proof and mosquito repellent dyes available in natural form. Various natural dyes contain tannin which can also act as a moth proofing agent. It has been reported in a research that the natural dyes having more than about 40% tannin is effective as an anti-moth agent. In various studies, it was reported that natural dye extracted from Saffron flower waste, onion skin, henna, myrobalan, silver oak leaf, madder, wall nut, dholkanali and yellow roots provides anti-moth properties after application on textiles [105]. Application of dye extracted form pomegranate peel with polyvinyl alcohol can act as mosquito repellent [106]. The mosquito repellent property of synthesised *4*-*Amino*-*N, N*-*diethyl*–*3*-*methyl benzamide* (MD) coupled with three different naphthol were assessed. Cotton fabric dyed with MD and naphthol showed very good and durable mosquito repellence. *N, N*-*diethyl*-*m*-*toluamide* (DEET) is used to synthesise the MD [107]. Pomegranate peels Extract can also act as mosquito repellent dye after its application on textiles.

Moth proof dyes were applied using exhaust method in which condition such as (Concentration of colourant-5%, temperature. 90°C degree, M:L- 1;:40, and pH 5–6, were maintained. Simultaneous dyeing with mothproofing agent on wool fabric were also reported. Result of this study showed that undyed and only mordanted fabric provides lesser protection from *D. maculatus* in comparison to madder dyed wool fabric. Mosquito repellent dyes are applied on fabric using either using exhaust method, pad dry cure and microencapsulation methods. [108, 109].

Mothproof and insect repellent dyes is textile museum and library to protect the textiles and books. Mosquito repellent dyes can also be applied to the children's clothing, pram and curtains [110] (**Table 2**).
